Tài liệu Storage Management pdf

4667-8 ch16.f.qc 5/15/00 2:07 PM Page 605 16 C H A P T E R Storage Management ✦ ✦ ✦ ✦ In This Chapter T his chapter introduces Windows 2000 storage A new addition to the operating system is a dynamic storage management environment that essentially provides “free” fault-tolerance (RAID-1 and RAID-5), enforceable disk quotas, and an MMC plug-in that replaces the clunky disk management environment of Windows NT 4.0 Windows 2000 Storage If there are three things that every IT or network administrator can be sure of happening regarding storage, they are the following: Overview of Windows 2000 Storage Storage Management Disk Management Dynamic Volumes and Fault-Tolerance The Storage Quota System Troubleshooting ✦ No matter how much hard disk storage you plan for, or think you need, you will always need more ✦ A hard disk will crash or falter within the lifetime of its host computer system ✦ A hard disk will crash at the worst possible time (usually for you) Applications and servers crash, and users get peeved when you run out of storage or you lose storage When you lose storage that was keeping critical data — data keeping the company alive — your world turns inside out Data loss costs us billions every year There are many examples where losing data destroyed a business, and where a good set of backups saved a business from certain disaster There are four actions you need to take to counter or survive the fallout from the three certainties: ✦ You need to evaluate your storage needs ✦ You need to develop policies for sound storage use ✦ ✦ ✦ ✦ 4667-8 ch16.f.qc 606 5/15/00 2:07 PM Page 606 Part V ✦ Availability Management ✦ You need to develop and follow a storage implementation plan ✦ You need to implement a disaster recovery and backup/restore plan The file system, storage management, and fault-tolerant capabilities of Windows NT were short on features and manageability, and did not support the 99.9 percent availability initiative (see Chapter 1) Administrators frequently turned to third-party products to keep their data safe Microsoft has responded to your needs, finally, with three very useful storage services: Disk Management Service, Removable Storage, and Remote Storage These services depend on the NTFS 5.0 file system for many features In this chapter, you will investigate these three services You will be able to plan your storage needs and decide what components of the Windows 2000 Server storage services meet your objectives and needs Storage Management To evaluate your storage needs, consider first the practice of storage management Storage management is practiced on three tiers: You need to manage access to storage (media), you need to manage access to data (availability), and you need to protect data (backup/restore) Let us first look at the access to storage tier Access to Storage Storage is located in two places on a network: on the host server from the perspective of the server and on a remote volume from the perspective of clients Computer systems require local storage on which to store system files and boot files to start operating systems and begin services You not need large volumes of storage for local operating systems and boot files The most any server will require is a partition of about 2GB, and that should easily service the OS files and server registry It should also be sufficient for local services, processes, upgrades, service packs, uninstall folders, and more Do the local volumes need to be particularly fast? Not necessarily, because access to boot files is only needed at startup and a fully functional server, in full production, seldom updates the system files or the registry So, you not need to create volumes that provide fast I/O, and you not need to spend a lot of money on very fast disks Note Storage considerations for client workstations may be very different than servers, which is what we are largely concentrating on in this chapter However, workstations and thin clients not need large volumes, and the practice of locating most applications and data on network servers (good for licensing, security, and backups) is fast becoming the universal practice again 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 607 Chapter 16 ✦ Storage Management The storage access tier goes down yet another level: data access Within the host computer, you can configure a single disk or an array of disks to hold data Data disks need to be built according to the needs of your organization and the purpose of the server The data volumes will typically hold applications that run on the server, databases that hold systems data, such as Active Directory, WINS, DNS and DHCP databases, and more Your data volumes may need to be fast If your applications or services will make numerous reads and writes to the data volumes, you will need to plan for fast I/O solutions Depending on your budget, you may be in a position to spend a little more money for fast disks, or you might consider striping volumes instead, or striping volumes on fast disks You need to note the type of applications that will be opened from the data volumes, the type of data that will be accessed from the volumes, and the number of users and applications that need to simultaneously read and write to the volumes You shouldn’t need to calculate data-access time, but certain applications may require you to calculate latency, disk performance, access times, transfer rates, and so forth Good examples of such applications are busy shopping carts on Web sites or database servers on the company intranet The server and hard disks may have to service as many as 1,000 concurrent requests for data at any given time And these requests may come to the hard disk as requests to write data and to read data, in which case you need to establish acceptable levels of performance for data access time and for transfer rate (the time it takes to retrieve and save data to the media) The three benchmarks of hard disk performance should be understood because they may be important to your applications When you are dealing with tens of thousands of hits a day on a Web site, or a massive data transformation operation, hard disks can take a knock A very busy mail server can chew through several disks in its lifetime The three benchmarks are as follows: Access time This is the time it takes for a hard disk to register a request and prepare to scan the surface of a disk Seek time This is the time it takes for a hard disk to find and assemble all the parts of a file Transfer rate This is the time it takes for a hard disk to transfer data on and off the disk Another angle on storage access is space If your databases are expanding and users are generating new files every day, you will need to watch disk space 607 4667-8 ch16.f.qc 608 5/15/00 2:07 PM Page 608 Part V ✦ Availability Management consumption and plan accordingly Your policy should be one in which every effort should be made (within budget and the requirements of the business) to continually strive to keep the volumes from filling up more than, for example, 70 percent of the available space reported to applications Depending on your requirements and the rate of usage, your policy might dictate that you keep disks at less than 50 percent or 60 percent capacity at any given time You have several options in managing disk capacity, and how and what you choose to will vary from server to server, application to application, and business to business The following list highlights the options you have, made possible with Windows 2000 storage services and technology: ✦ Volumes can be spanned, or extended This is the process of chaining volumes of unallocated space together When a disk approaches the capacity threshold that you have set, a new volume can be “bolted on” to extend the capacity For faster I/O on spanned volumes, you can also add striping support ✦ Users can be given enforceable disk space quotas, as groups (all users have the same quota) and as individuals As you will later see, it is possible to assign an across-the-board quota giving all users on a volume the same quota, and thereby create a ceiling no user can violate ✦ You can mount into the file system name space on a given folder This topic is introduced in this chapter and given full coverage in Chapter 21 ✦ You can redirect folders to volumes and root shares on other servers This is a feature of the so-called distributed files system (Dfs), which is fully covered in Chapter 21 ✦ You can compress data on volumes Compression is covered in Chapter 21 ✦ You can create a Hierarchical Storage Management system (HSM) With Windows 2000 Remote Storage Services (RSS) and Removable Storage Services (RSS), you can automatically move files that are not needed on a local or network volume to removable media, such as tapes and portable disks The HSM system is introduced in this chapter and dealt with at length in Chapter 21 ✦ Windows 2000 also introduces a highly sophisticated automated data encryption service, which is discussed in Chapter 22 Important factors to consider with any of these options are the data-transfer rate, the data-access rate, and the latency or delay in getting files from redirected or remote storage to the users The bar chart in Figure 16-1 provides some insight into the data-transfer and data-access strengths of the various storage solutions The Distributed File System (Dfs) is at the top of the availability scale, and indicates high scores for number of concurrent users and capacity, but a lower score for response On the other end of the availability scale are striped volumes, which are not fault-tolerant, but score high on the number of users, capacity, and response Whatever option works for you, you will still have to some lab work to get accurate feedback 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 609 Chapter 16 ✦ Storage Management Tip Check your application’s documentation or call the vendor’s technical support for the recommended storage requirements Users Capacity Response Dfs RAID-0 RAID-5 CD-Jukebox Availability CD-Array CD-R/DVD Basic Disk HSM Tape library Striped Volumes Figure 16-1: Strengths of the Windows 2000 storage options Access to Data The second tier of storage management is maintaining availability If your business and applications call for 99.9 percent availability — applications and users need uninterrupted access to data — you should consider all available hardware and software options The following services or features of Windows 2000 storage can be employed to meet the 99.9 percent initiative: ✦ Mirrored volumes: Windows 2000 dynamic volumes allow you to create RAID-1 compliant mirrored volumes 609 4667-8 ch16.f.qc 610 5/15/00 2:07 PM Page 610 Part V ✦ Availability Management ✦ RAID-5 fault tolerance: RAID-5 or striping with parity is fully supported You can build, manage, and break a RAID-5 array with three or more disks ✦ Fail-over servers: The above solutions can be cloned onto hot standby servers without automatic fail-over Automatic fail-over is a feature of the clustering service that is supported in Windows 2000 Advanced Server and Windows 2000 Datacenter Server, which are not covered in this book Windows 2000’s fault-tolerant dynamic volumes are given comprehensive coverage in this chapter You can also consider the HMS and Dfs solutions described previously as additional support for the 99.9 percent availability initiative Protecting Data Data protection initiatives need to respond to several threats: file corruption, theft, natural disasters, virus attacks, and lost data (user-deleted files, fried hard disks) The primary services that support the backup and restoration of data are as follows: ✦ Removable Storage Services: Discussed later in this chapter and in Chapters 17 and 21, Removable Storage Services work with backup technology, media, and robotics to provide a comprehensive data protection media management system ✦ The Backup/Restore Service: This is fully discussed in Chapter 17, and as part of the HSM system in Chapter 21 ✦ Remote Storage Services (RSS): Also discussed in Chapter 21, the RSS is responsible for moving online data to offline backup technology RSS, the Removable Storage Services, and Backup/Restore work in concert to affect an HSM system Support for Legacy Systems Almost all Windows 2000 disk fault tolerance and disk extension is possible via the Disk Management service, which allows you to create dynamic volumes on which you can configure extended volumes, mirrored volumes, and RAID-5 arrays You can also easily manage these volumes However, Windows 2000 dynamic disks are not compatible with older versions of Windows or any other operating system In other words, Windows 95, 98, and NT cannot read from or write to dynamic volumes installed as local volumes Note Although dynamic volumes can only be locally accessed by Windows 2000, this does not mean you cannot read or write to a share or a publishing folder in Active Directory residing on a dynamic volume 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 611 Chapter 16 ✦ Storage Management At the time of this writing, there was no way to upgrade or service pack a legacy 9x or NT 4.0 machine to read a dynamic volume A study of the Windows 2000 architecture suggests that the support for dynamic disks is deep in the new operating system and not something that can be tacked onto NT with a service pack Disk Management Services Windows 2000 provides many built-in features that can assist in making a sound storage plan a reality The operating system provides sophisticated disk and volume management in the form of two disk-centric services: the fault-tolerant disk manager (FTDISK) and the logical disk manager (LDM) FTDISK and its associated tools, like FTEDIT, are inherited from Windows NT; it is a basic disk utility The LDM is a new introduction responsible for the management of dynamic, logical volumes Dynamic volumes are storage objects, abstracted above disk spanning partitions and infused with dynamic or virtual storage attributes that unfortunately only Windows 2000 understands The Windows 2000 disk/volume management architecture is illustrated in Figure 16-2 OTHERS WINDOWS 2000 AND NTFS 5.0 FTDISK LOGICAL DISK MANAGER BASIC DISKS DYNAMIC DISKS Mirrors Striped Volumes Spanned Simple RAID-5 Figure 16-2: Windows 2000 disk/volume management architecture 611 4667-8 ch16.f.qc 612 5/15/00 2:07 PM Page 612 Part V ✦ Availability Management Employing the services of both FTDISK and the LDM, Windows 2000 storage services can basically be split into two tiers: Basic Storage and Dynamic Storage Disks can be configured for one of the two systems The differences and employment of the two systems is explained later in this chapter; however, one major benefit of dynamic storage is the support for mounted volumes Mounted Volumes In terms of dynamic disks and dynamic volume management, mounted volumes provide a means of rapidly adding and removing disk space from a system Installing or importing a dynamic disk and then mounting the volume anywhere in the file system namespace, such as into a folder, is an elegant solution to the problem of adding or removing disks from a system without shutting down the computer and betraying the 99.9 percent availability initiative Mounted volumes can be constructed out of single dynamic volumes or fault-tolerant arrays of dynamic disks Because a dynamic volume is an object that encapsulates disk space, you can graft dynamic volumes together in various ways to extend and protect the storage space (spanning, mirrors, and so on) Then you can take the entire extent (capacity) of the volume and graft it into the file system namespace For example, you can mount the volume onto the d:\ disk as d:\data and then extend the d:\data volume as applications, service level, and availability require Volumes, and thus the volume mount points, can be extended as needed The only limitation is the physical hardware architecture (usually SCSI) and the physical storage space for the hard disk Mounted volumes consist of dynamic disks created in the Disk Manager, discussed later in this chapter However, you need to become familiar with the advanced features of NTFS before you can mount volumes into the file system We cover this important topic, volume mount points, in Chapter 21 Disk Defragmentation Another topic worthy of introduction here is disk defragmentation NTFS is in itself an orderly and efficient file system, and we, and many administrators we know, have never really needed to defragment an NTFS disk However, disk defragmentation has been introduced into Windows 2000 We discuss it later in the storage housekeeping section of this chapter and in depth in Chapter 21 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 613 Chapter 16 ✦ Storage Management Removable Storage Windows 2000 is the first Microsoft product to introduce a holistic removable storage management system built into the operating system Removable storage is any media that can be taken out of host equipment and relocated off site Removable storage typically includes tape drives systems, recordable and rewriteable compact disks and DVD-ROMs, and even removable hard-disk technology such as ZIP disks, portable or external hard drives, and more Removable Storage Services allows you to install and configure single tape drive units (like Quarter Inch Cartridge) or highly sophisticated and expensive robotic library and archive systems (such as CD-R changes and DLT systems) You can also gather your removable media resources into collections of removable storage, known as a media pool Note Removable media, such as QIC, DAT, and DLT, are discussed in Chapter 17 Media pools refer to two concepts in backup administration First, they refer to collections of media, regardless of the type, from which a backup system can check out and check in media required for any instance of backup or restore processing Then there are media pools, a la Windows 2000, which are collections of tapes, carts, and disks organized under a single management system Media pools are not new to IT, and a stronger definition might be “a collection of like and unlike storage media collected together as a single storage resource.” Windows Backup and Remote Storage Services draw on media pools according to the rules and regimens set up to protect data, and they support 99.9 percent availability Remote Storage and HSM Remote storage is the service that makes Windows 2000 look a lot like UNIX HSM is the widely known (in UNIX and mid-range circles anyway) acronym for Hierarchical Storage Management, which is a major feature of Remote Storage Services, or RSS Like removable storage services, Windows 2000 is the first Microsoft operating system to introduce HSM capability But please not go running off to your server to dig around in RSS to look for the HSM option, because you will not find it HSM is really a system (some call it a philosophy) and consists of numerous components and services that unite to form a cascade of continually migrating and translocating data throughout the enterprise information network (technically speaking, RSS is an HSM system) HSM supports the 99.9 percent availability mission by moving unused data off local storage when 613 4667-8 ch16.f.qc 614 5/15/00 2:07 PM Page 614 Part V ✦ Availability Management the disks start getting full, or at pre-configured intervals It can also participate in a generation-rotation backup system, as discussed in the next chapter, but this is not yet a feature of RSS The hierarchical system of data storage has several levels There is a data retrieval level, which starts out at the top of the hierarchy Data at the top of the hierarchy is online and always in a highly available or retrievable storage state Data at the bottom end of the hierarchy is usually offline and in a latent state of retrieval High-availability data resides on local fast hard disks, in fast access network storage silos or storage area networks (SANs), or arrays of hard disks servicing clusters At the lower end of the hierarchy, data is stored on tape cartridges, compact disc libraries, tape libraries, and even slower hard disk arrays How does the data get from the high-availability state to the other end of the hierarchy? This is what you set up in RSS A file that passes a test — such as time since last accessed — is moved off the fast front-line volumes and down the hierarchy to the slower media In a well-designed system, the files that are not being accessed eventually end up on tapes checked into a library The actual file migration can be triggered according to events, such as hard disk space checking, and so on The RSS does not move all evidence of the file off the hard disk at the top end, but leaves an empty file name on the volume as a marker All the data is drawn out of the file and sent to remote storage From the user’s perspective, the file still exists on the hard disk When the user needs to access it again in the future, the file is checked out of the archive system and returned to its original location In fact, the user need never know the data was actually somewhere else in the system The only giveaway would be the slower access time when trying to open a large file that is in remote storage The storage level breaks out into two hardware-specific levels The lower level is the remote storage level, which is responsible for the storage of data that has been drawn from local storage where it is no longer being accessed Remote storage monitors file space on the local volume it is managing When available space drops to a certain level, remote storage will move “stale” files to free up hard disk space The capabilities of the remote storage system are the following: ✦ You can set up and configure remote storage devices such as tape drives and libraries ✦ You can configure volumes for RSS management and HSM ✦ You have more disaster recovery options and more tools to protect the 99.9 percent availability initiative ✦ You can manage volumes for remote storage and HSM 4667-8 ch16.f.qc 628 5/15/00 2:07 PM Page 628 Part V ✦ Availability Management Extending Simple Volumes (Spanning) The process of creating dynamic volumes and then extending them or adding them to existing resources is called spanning, or creating spanned volumes Spanning is the process of combining unallocated space from multiple drives into one logical volume After you have created a simple volume, as instructed previously, you will now add it to an existing volume The following checklist applies to extending volumes: ✦ Dynamic system disks, which contain boot information, cannot be extended ✦ Spanned or extended volume sets cannot be broken without destroying the data on the disk If you need to break a spanned volume, the data must be backed up ✦ You cannot extend a volume by using another volume that has already been created, or that was a basic volume that was upgraded to a dynamic volume You can only use unallocated space If you wish to use a volume for spanning, you have to first back up any data you need and then delete the volume ✦ Spanned volumes, as explained earlier, cannot be used for fault tolerance To span volumes, follow these steps: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into “Graphical” View by selecting View ➪ Bottom Right-click the disk showing unallocated space and select the option “Create Volume.” The Create Volume Wizard launches and takes you through the procedure You can choose to use all the unallocated space or a portion of it During the course of creating the extension, you are going to be asked for a drive letter Have a chosen letter ready; you don’t want to be wasting time confirming this when creating the extension It is important to make sure that applications will not choke on the drive letter you assign to the extension For example, you may have a database management system (DBMS) already installed on the media that maintains a drive mapping for certain tables to D: If you come along now and change the drive letter to X:, your DBMS will not work as intended The drive letter may be changed later, but it may be inconvenient and even impossible if the drive letter you need is already assigned To break a spanned volume, follow these steps: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 629 Chapter 16 ✦ Storage Management Right-click any of the disks in the spanned or extended set (They will be the same color and will have the same drive letter.) Select the option Delete Volume, as illustrated in Figure 16-7 Before you can delete the volume set, you will be warned that the entire span is going to be trashed, along with any data stored on it Figure 16-7: Volume management options After going ahead with the volume delete, the dynamic disks are returned to their Unallocated state The disks are now ready for export or use in a fault-tolerant configuration Creating and Managing RAID-0 Volumes (Striping) The process of creating striped volumes and then extending them or adding them to existing resources is called striping or creating striped volumes The following checklist applies to striped volumes: ✦ Dynamic system disks, which contain boot information, cannot be striped ✦ Striped volumes cannot be broken without destroying the data on the disk If you need to break a striped volume, the data must be backed up 629 4667-8 ch16.f.qc 630 5/15/00 2:07 PM Page 630 Part V ✦ Availability Management ✦ You cannot stripe a volume by using another volume that has already been created, or that was a basic volume upgraded to a dynamic volume You can only use unallocated space If you wish to use a volume for striping, you have to first back up any data you need and then delete the volume ✦ Striped volumes, as explained earlier, cannot be used for fault tolerance To stripe volumes, follow these steps: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom Right-click the disk showing unallocated space and select the option Create Volume The Create Volume Wizard launches and takes you through the procedure Follow the steps described previously in the Spanning section To break a striped volume, the following: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom Right-click any of the disks in the striped volume (They will be the same color and will have the same drive letter.) Select the option Delete Volume Before you can delete the striped volume, you will be warned that the entire volume is going to be trashed, along with any data stored on it After going ahead with the volume delete, the dynamic disks are returned to their Unallocated state The disks are now ready for export or use in a fault-tolerant configuration Creating and Managing RAID-1 Volumes RAID-1 level sets are fault-tolerant mirrored volumes You create mirrored sets in a similar fashion to extending volumes as described previously The following checklist applies to creating mirrors: ✦ Mirrors are created using two dynamic disks Write down the disk IDs that you are going to mirror and decide on how much hard disk space you are going to allocate to the mirrored volume ✦ You can use unlike disks, but you must remember that the fault-tolerant storage space is only as large as the smallest disk 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 631 Chapter 16 ✦ Storage Management ✦ You cannot mirror a volume by using another volume that has already been created, or which was a basic volume that was upgraded to a dynamic volume You can only use unallocated space If you wish to use a volume for a mirror, you have to first back up any data you need and then delete the volume To mirror volumes, follow these steps: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom Right-click the disk showing unallocated space and select the option Add Mirror The Create Volume Wizard launches and takes you through the procedure You can choose to use all the unallocated space or a portion of it, as illustrated in Figure 16-8 Figure 16-8: Selecting the disks to mirror Click Finish to create the mirror job and continue until the entire process is complete The mirrored set will begin formatting as soon as it has been created Figure 16-9 shows the mirror set created and formatted (volume E:) It also illustrates that the mirror has been established on 2GB of dynamic disk space The remaining unallocated space can be used for creating simple volumes, striped volumes, or one new spanned volume (which is what we decided to do) 631 4667-8 ch16.f.qc 632 5/15/00 2:07 PM Page 632 Part V ✦ Availability Management Figure 16-9: The mirror volumes created and formatted as a single drive Creating and Managing RAID-5 Volumes You create RAID-5 volumes in a similar fashion to the RAID-1 sets described earlier The following checklist applies to creating RAID-5 sets: ✦ RAID-5 volumes are created using three or more dynamic disks Write down the disks that you are going to include in the configuration and decide on how much hard disk space you are going to allocate to the volume ✦ You can use disks of different sizes, but you must remember that the faulttolerant storage space on the smallest disk is what gets configured on the other disks ✦ You cannot configure a RAID-5 volume by using volumes that have already been created, or which were basic volumes that were upgraded to dynamic volumes You can only use unallocated space If you wish to use a volume for a RAID-5 configuration, you have to first back up any data you need and then delete the volumes or partitions ✦ Follow the advice given in the checklists for the previously described volume configurations 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 633 Chapter 16 ✦ Storage Management To install RAID-5 volumes, the following: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom Right-click the disk showing unallocated space and select the option Create Volume The Create Volume Wizard launches and takes you through the procedure, which is not much different from the disk mirroring choice described earlier Click Finish to create the RAID-5 volume and continue until the entire process is complete The RAID-5 set will begin formatting as soon as it has been created Note You can gather up any unused space left over from creating mirrors or RAID-5 volumes and use it to span or stripe Importing Volumes Dynamic volumes can be removed from one computer and installed into another Windows 2000 computer without having to reconfigure the hard disk As we mentioned earlier, dynamic volumes are self-identifying The attributes of the volume are persistent even after disconnection from the host in which they were configured To import a foreign disk, follow these steps: Ensure the disk is in a healthy state before removal After inserting the disk into the new host, open Computer Management and select Disk Management Select Action ➪ Rescan Disks Right-click the disk marked Foreign and then click Import Foreign Disks Proceed with the import When the import process is completed, select the Rescan Disks option again to verify that the import worked You should also this on the system the disk came from to bring disk information current Managing Storage with Disk Quotas Disk quotas were introduced to Windows NT with Service Pack 4; however, the quotas were not easy to enforce, and few administrators we know tried to work with them They were also set via user profiles, which often interfered with a user’s workflow Windows 2000’s disk quota services, however, allow you to allocate space to users at the volume level and enforce them The new quota technology is a very different animal 633 4667-8 ch16.f.qc 634 5/15/00 2:07 PM Page 634 Part V ✦ Availability Management Note Disk quotas are only supported on NTFS 5.0 Volumes Before we get into the doing part, let’s discuss the why part: Why Do You Need Disk Quotas? Remember what we said at the beginning of this chapter: No matter how much hard disk space you think you need, it is never enough It is one thing managing your own hard disk space, the storage requirements of applications and databases, and so on; managing users is a different story Keeping track of available storage is a continuous effort, but it is essential All computer services depend on hard disk space If the disk runs dry, the IIS services like FTP will fail, databases will crash, backup jobs will collapse, and systems will die The disk quota is a means of controlling and enforcing a user’s ability to save data to a volume It is enforced at the user level, but restricted (and limited) to a specific volume You can set a user’s quota and let Windows 2000 monitor the user’s disk consumption Then, when the user attempts to save data to the folder that will use up the quota, Windows will react with a warning at a certain threshold and then deny access to the user until he or she has deleted unused or unnecessary files Quotas, thus, not only help you protect platter space, they force your users to their own housekeeping In the storage plan hinted at previously, you will determine how much storage you need for a particular server or application Let’s say a server hosts a SQL Server 2000 database environment, and you devote 20GB to it, leaving 10GB for the application and 10GB more free for future growth and users The wild card is users What if you have a share-point on the same volume as the database and for one reason or another it cannot be relocated to another server? We have such servers in commission, and on Windows NT 4.0, we have to constantly watch them With disk quotas, you can set a cap on the hard disk consumption of all your users and enforce the limits In the SQL Server database example, you could assign 5GB for future application consumption and cap the share-point at 5GB, a total of 10GB (note in the plan what the SQL Server administrator has configured for automatic expansion of the database sizes) How you that? Let’s now examine the quota service, learn how to apply and enforce quotas, and then explore the results How the Quota System Works The quota service or system is not difficult to set up and manage, but you should understand how it works and any limitations that would affect how you set up volumes and services in the future 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 635 Chapter 16 ✦ Storage Management Ownership Quota calculations are based on ownership When you create a folder or file, the OS adds the disk overhead of the new objects to your account This makes for an extremely robust and manageable situation and forces you to account for your actions on a volume With this system of checks and balances, a user cannot simply “pick up” a file and copy it, because by doing so he or she gains ownership to the copy and the file size is debited against his or her quota account Permissions have no bearing on the quota system, and, as you will soon discover, the quota limit is enforced on the whole volume, regardless of your rights and permissions in a particular share, folder, or file Be aware, however, that many applications can change ownership of files depending on who accesses a file and when This means that in share-points where sharing files is the order of the day, quota levels will be in a constant state of flux A user might end up over the quota limit just by looking at files To counter this, the quota technology can employ a threshold, and you can decide at what point users get notice from the file system that they are running out of space Many applications also function in the OS, in the context of a user account A good example is your backup program, which may need to things as a user account in the Backup Administrator’s group You would likely not be restricting administrator or system accounts However, an application could work in the context of a user account and be given a quota limit, and this would be a very effective means of putting the reins on an application that has a habit of filling up volumes with log entries and the like You can also instruct the quota service to write entries into the event log, giving you data on which to set triggers for disk space analysis algorithms You would need to experiment with your applications, but with threshold reporting and log entries, there is no longer an excuse that the server or application crashed because the computer ran out of disk space The quota system gives everyone unlimited disk space “credit” as soon as quotas are enabled on a volume Until you set limits and thresholds, no restrictions apply File compression The quota service ignores compression and applies the original size of a compressed file to the account The reason for this is that file compression ratios vary across different file types and versions For example, graphics files might not compress as readily and uniformly as text files or applications Disk space/quota analysis The quota service or system, once enabled on a volume, gathers disk space usage information about all users who own files and folders on a volume This information is reported to the Quota Entries for Local Disk (disk), as illustrated in Figure 16-10 635 4667-8 ch16.f.qc 636 5/15/00 2:07 PM Page 636 Part V ✦ Availability Management This information is useful for determining who has access to file objects in a volume without having to drill into folders and dig around in user groups (You could look at sessions, but they are not persistent; ownership survives disconnection from the volume) Figure 16-10: The quota entries for a local disk Setting Disk Quotas In order to set quotas, you need to gather information about who’s using what and where on a volume User information that is not specifically reported to the Quota Entries application upon startup of the system has to be looked up and added manually To set up quotas, the following: Make sure you are a member of the Administrators group You need permission to set quotas Double-click My Computer and right-click the disk on which quotas will be enabled This action loads the Local Disk Properties dialog box shown in Figure 16-11 This is the quickest way to get to the Disk properties dialog box if you not have the Computer Management console open Another route to disk Properties is via the Disk Management Snap-in in Computer Management, but this method isn’t as efficient In Disk Management, put the drives into Disk view, right-click, and select Properties The (physical) Disk Properties loads to reveal the volumes on the media Right-click the volume to enable the Volume Properties button Click the Properties button (whew) to launch the Local Disk Properties dialog box Click the checkbox “Enable quota management.” This starts up the service and allows the quota system to begin monitoring user disk space consumption Click the checkbox “Deny disk space to users exceeding quota limit.” This option causes quota services to send an alert to an individual Checking this option is not sufficient to deny a user disk space You still need to set limits across the board or in the Quota Entries for Local Disk application 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 637 Chapter 16 ✦ Storage Management Figure 16-11: The Quota tab Check “Do not limit disk usage” to allow users to use as much hard disk space as they need Or check “Limit disk space to” and provide a size in KB, MB, or higher in the drop-down lists provided This value is an “across the volume” disk space limit that affects all users In other words, when the limit has been reached, no user can save a file or create a new one This is a quick and highly effective means of putting a ceiling and a threshold on disk space consumption on a volume Next, set the warning level to an amount you feel appropriate This is the threshold After the warning has been issued, the users can continue using hard disk space until they max out and can no longer save to the disk Finally, you can check the option to have quota services log events when users exceed their limits and when users exceed their warning levels Adding disk quota entries To add quota entries, click the Quota Entries button in the Local Disk Properties dialog box for the disk You can insert quota entries as follows: Select Quota from the application menu and then select New Quota Entry The standard Select Users/Add dialog box loads, from which you can select and install users into the Entries list 637 4667-8 ch16.f.qc 638 5/15/00 2:07 PM Page 638 Part V ✦ Availability Management Common Sense Disk Quota Management If there is one thing users (in fact anyone) not like to be told is that they have “exceeded their limit.” That’s akin to being told by the bank that “you have no more money and have exceeded overdraft limits.” The following suggestions are intended to help you make wise use of this critical service: ✦ Enable thresholds for all users It is not a good idea to bring a user’s workflow to an abrupt end At least with thresholds, the user can take evasive action, such as deleting files or moving files to other volumes or backups before the quota ceiling kicks in Also, set a realistic threshold; it makes no sense to warn users that they are about to run out of storage space and then kick in the limit as soon as they try to save their work ✦ Be careful not to set quotas before users have had a chance to install any legal applications or components on the volume they need access to If this happens and the installation crashes because the quota limit is reached, you could log on to the server as an administrator and reinstall the application The administrator or Administrators groups would then own the new installation, and this would not affect the quota Notice that we put legal into italics above The quota system helps prevent illegal installations (Group Policy works for this, too) and can put an end to software piracy taking place under your nose (users just love to copy whole CDs to storage; we’ve all done it) ✦ Monitor hard disk usage and individuals or problem users on a continuous basis A flexible quota system works best, but you need to weigh flexibility against cost of administration ✦ Avoid groups of users who all log on under the same user ID and password A lot of companies this, and it makes no sense; it’s insecure and risky It is difficult to keep track of a quota when four-score plus 20 are using the same ID ✦ Keep track of quotas for users who no longer need to access or store data on a volume You cannot delete the quota until the user has removed all the files or transferred ownership Troubleshooting Unfortunately, managing disk and storage is not a set-it-and-forget-it task ZAW and change control initiatives aside, like most other server and administrative tasks, you have to regularly monitor your storage Volume States During the lifetime of a disk or dynamic volume, the integrity of the disk, and thus the data, may become threatened Disk Administrator posts status information on each disk or volume, reflecting the state it is in Table 16-2 represents the various states shown in Disk Management, and the problems, if any, to expect with each state 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 639 Chapter 16 ✦ Storage Management Table 16-2 Volume States State Description Healthy The volume checks out for normal operations, and there are no known problems This status is displayed for both basic and dynamic volumes Healthy (At Risk) The volume is available, but Windows 2000 has detected read and write (I/O) errors on the disk This state is only reported on dynamic volumes This status is reported even if only one of the volumes on the disk reports I/O problems Initializing This is reported by the LDM and only applies to dynamic disks There is no need for user intervention unless the system hangs and the status remains unchanged The correct sequence of events is that the status returns to healthy Resynching This status applies to basic mirrored sets and dynamic mirrored volumes Resynching is the process of making sure that both sets of data (one on each mirror) are identical The resynching process might take a long time if the mirrors are large Do not attempt to access the volumes while the resynching is in process Regenerating This status applies to RAID-5 sets and dynamic RAID-5 volumes RAID-5 volumes are accessible during the regeneration process When the task is complete, the disk status returns to healthy Failed Redundancy This status applies to RAID-5 sets and dynamic RAID-5 volumes It means that one of the disks in the array is offline and faulttolerant integrity is at risk Fault tolerance is hosted when you are down to two disks in the array You can continue to access the volume, but if you lose the second disk in the array, you lose the volume and the data because the striping and parity goes south If you have five disks or more in the array, you have more time to replace the disk, but complacency is not a virtue in IT or network administration Failed Redundancy (At Risk) This status applies to dynamic RAID-5 volumes It means that the array is no longer fault-tolerant and that I/O errors have been detected on the media This status appears on all the disks in the array The disk and the fault-tolerant status can be reactivated Failed This status applies to both basic and dynamic disks It means that the volume cannot be restarted and will require user intervention 639 4667-8 ch16.f.qc 640 5/15/00 2:07 PM Page 640 Part V ✦ Availability Management When Good Disks Go Bad Should a volume report “Failed Redundancy,” “Failed Redundancy (At Risk),” or just “Failed,” there are several calls you can make to the FTDISK and the LDM Step 1: To attempt to reactivate Failed Redundancy, try the following: Click the Disk Management node on the Storage tree to load the Disk Management Snap-in Put the disk list into Graphical View by selecting View ➪ Bottom Right-click the disk indicating Failed Redundancy status, and select the Reactivate Disk menu option for dynamic volumes or Repair Volume for basic disks If the reactivation succeeds, the volume recovers itself and returns to Healthy status Step 2: If a Failed Redundancy disk does not recover, try the following: Attempt to reactivate the disk manually This is done using the Reactivate Volume command for dynamic disks (both Mirrors and RAID-5) and the Resynchronize Mirror command for basic mirrored disks Both commands should normally execute automatically after executing the commands in Step If a basic RAID-5 disk is still offline, you can try to run the Regenerate Parity command If the disk is still offline and second attempts to reactivate fail, the disk has to be replaced To replace a failed mirror, go to Step above, but select Remove Mirror or Failed RAID-5 Disk region After extracting the bad disks, you should follow the instructions for creating mirrors earlier in this chapter To repair a RAID-5 volume, you need to use the Repair Volume command, which will take you through replacing the culprit disk To repair a failed mirror on a basic disk, you can use the Repair Volume command If the disk does not return to healthy status, you should then try to force the repair using the Resynchronize Mirror command If a basic RAID-5 disk fails, use the Repair Volume command to return the disk to healthy status The Repair Volume command attempts to regenerate parity automatically If the volume still reports the Failed Redundancy status, try using the Regenerate Parity command manually If the basic disk is still offline, it will have to be replaced Step 3: To attempt to reactivate Failed Redundancy (At Risk) disks, try the following: Try to reactivate Failed disks in the same fashion as Step above, then attempt to reactivate the disks manually 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 641 Chapter 16 ✦ Storage Management If initial attempts to return the Disk to healthy status succeed, the status may report the Failed Redundancy status (minus the At Risk part) This is usually a good sign, and going through the paces in Steps and previously should return the disk to healthy status The likely scenario is that the disk data is out of sync or parity information needs to be regenerated Use the Reactivate or Resynchronize commands described previously and then run Chkdsk on the dynamic volumes from the command line (Chkdsk may not work for basic disks) If you are still having no luck, you may need to replace the hardware, in which case if you follow the advice in Chapter 17 and perform regular backups, you not have a problem If you don’t have backups, pray that a third party can recover the data from the dead hardware Step 4: To replace disks, the following: If you can spare disks from other computers, you can import them into the new host using the Foreign Disk import options described earlier in this chapter This option only works for dynamic disks, however If you need to replace basic disks and you are not using hardware RAID and hot-swappable components, you will have to power down the server Install the disks and, using the management options described earlier in this chapter, you can easily re-integrate the disks into the arrays Summary This chapter provided a thorough investigation of Windows 2000 storage services In particular, we covered the installation and management of local hard disks and the configuration and management of extended dynamic disks and fault-tolerant arrays Of particular importance is understanding both the benefits and limitations of dynamic volumes or disks On the one hand, the dynamic volumes is a great improvement in local storage management on the Windows 2000 platform On the other hand, dynamic volumes is not a pervasive standard It is still very much “Microsoft technology,” and other operating systems will choke on these volumes if you try to access them directly We still have a while to go in covering all of the Windows 2000 storage services Chapter 17 extends Chapter 16 with a discussion of media pools, backup, restore, and disaster recovery ✦ ✦ ✦ 641 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 642 ... be able to plan your storage needs and decide what components of the Windows 2000 Server storage services meet your objectives and needs Storage Management To evaluate your storage needs, consider... your storage needs, consider first the practice of storage management Storage management is practiced on three tiers: You need to manage access to storage (media), you need to manage access to data... remote storage and HSM 4667-8 ch16.f.qc 5/15/00 2:07 PM Page 615 Chapter 16 ✦ Storage Management When remote storage needs to check data into a library, it interfaces with the removable storage