... consists of virtual connections between the
nodes of a network independent of their physical layout.
– These logical signal paths are defined by DataLinklayer
protocols.
• TheDataLinklayer ... www.bkacad.com
Connecting Upper Layer Services to the Media
11
• To support a wide variety of network functions, theDataLinklayer is often divided into
two sublayers: an upper sublayer and an lower sublayer. ... DataLinkLayer Protocols- The Frame
31
• Remember that although there are many different DataLinklayer protocols that describe
Data Linklayer frames, each frame...
... Three Principles ofData Center Infrastructure Design
Page 5
Choosing the Right Mix
of Equipment
Since the total spend for network infrastructure
equipment is but a fraction ofthe entire data ... percentage of terminations as copper,
fiber optic cabling and connectivity is a significant part
of thedata center. Fiber links are also the most critical
links because they carry data to and ... gain significant benefits and savings throughout the life
of your data center.
The Three Principles ofData Center Infrastructure Design
Page 7
Deployment
The graphic below depicts a sample data...
... discourse. Inthe UK,
the FTSE (The Financial Times Stock Exchange Index) has introduced in 2001 the
FTSE4Good index for ethically high scorers. And this is just the latest inthe line of
a burgeoning ...
economies. Identifying the ethical push behind entrenching the concept of minimum
standards for corporate conduct inthe sphere of international law Muchlinksi
discerns a framework in which the moral ... consultancies.
Discussion ofthe moral responsibilitiesof business has come out ofthe
classroom and into both the financial press and the boardroom. Why?
9
J. Elkington, Cannibals with Forks: TheTtriple...
... these layers and their interaction. In recent years, the
importance ofthe cross -layer design at the PHY/MAC /link
layer has been reiterated through the emergence of many
innovative techniques, ... information
(e.g., the SNR information at thelinklayer or the queue size
at the baseband module).
The motivation for this special issue is the observation
that a cross -layer approach is particularly important ... cross -layer design has
been adopted. In short, the cross -layer methodology allows
certain important information to in uence decisions in a
layer that is originally not defined to use that information
(e.g.,...
... TRANSACTION PROCESSING, Vijay Atluri, Sushil
Jajodia, Binto George ISBN: 0
-
7923
-
7702
-
8
FUZZY LOGIC INDATA MODELING, Guoqing Chen ISBN: 0
-
7923
-
8253
-
6
INTERCONNECTING HETEROGENEOUS INFORMATION ... /Moscow
The Kluwer International Series on
ADVANCES IN DATABASE SYSTEMS
Series
Editor
Ahmed K. Elmagarmid
PurdueUniversity
West Lafayette, IN 47907
Other books inthe Series:
SEMANTIC MODELS ... 0
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DATA DISSEMINATION IN WIRELESS COMPUTING ENVIRONMENTS, Kian-
Lee Tan and Beng Chin Ooi; ISBN: 0
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0
MIDDLEWARE NETWORKS: Concept, Design and Deployment of Internet
Infrastructure,...
... Analysis ofthe Working Hypothesis 47
4. USE OF MEMORY AT THE I/O INTERFACE
51
1. Simulation using Time
-
in
-
Cache 52
3. Expectations for Memory Interaction 56
5. MEMORY MANAGEMENT IN AN LRU ... function of
window size. 95
Requests to persistent cylinder images as a function of
window size. 95
Requests to persistent files as a function of window size. 96
Distribution of file interarrival ... distinguish along a single
time line. 6
1.2 Distribution of track interarrival times. Each curve
shows a user or system storage pool at one of 11 sur
-
1.3 Distribution of page frame interarrival...
... exploit
them to best advantage. The emphasis ofthe book will be on the practical
applications of such results.
The focus ofthe applications examined in this book is on the portion of a
computer ... example of such a phenomenon
is not, by itself, sufficiently interesting to justify an entire book. Instead, the
“meat” ofthe present book comes from the ability ofthe hierarchical reuse
model ... based upon the explicitly hierarchical nature of most software. To
reflect the inferred “behind the scenes” role of hierarchically structured soft
-
ware, we adopt, in Chapter 1, the term hierarchical...
... percent of
the tracks. Since the beginning ofthe sorted list represents the best possible
cache contents, we may apply the definition of Ω(l) to obtain the following
upper bound on the hit ... Reuse Model 3
the LRU list, other than the requested track, remain linked together inthe same
order as before.
This algorithm has the net effect that the tracks inthe list always appear in
order ... at the opposite end ofthe list, called
the bottom, or Least Recently Used (
LRU) position, is the track for which the
longest time has passed since the previous reference. Therefore, in the
LRU
algorithm,...
... than any ofthe time scales of interest (some fraction
of one second). Thus, we will not bother trying to quantify the lower limit
but simply note that there is one. Inthe remainder ofthe book, ... track does of being referenced
in the next 20 seconds. Similarly, we should expect that the short term track has
the same probability of being referenced inthe next 1 minute, as the long
-
term
track ... does of being referenced inthe next 4 minutes.
By formalizing the above example, we are now ready to state a specific
hypothesis. Let the random variable U be the time from the last use of a...
... units of granularity. For example, the minidisk
cache facility mentioned earlier manages datain units of one page frame (one
block of 4096 bytes).
The unit ofgranularity used in managing the ... size. Then we may conclude that the population of tracks currently
visiting the cache is given by (1.13):
THE FRACTAL STRUCTURE OFDATA REFERENCE
Therefore,
By contrast, measurements ofthe single
-
reference ... STRUCTURE OFDATA REFERENCE
Let us first subdivide the entire visit into two parts:
1. The back end, starting with the last reference during the visit, and ending
when the track is removed from the...
... considering the require
-
ments of individual applications. In view of (1.20), such objectives provide a
valuable starting point for configuration planning. Let us, therefore, consider
the impact ofthe ...
These include both the VM storage pools already introduced, as well as the stor
-
age pools traced during a survey oftwelve moderate to large OS/390 installations
[ 17]. The figures include the ... reflected inthe average or single
-
reference
residency time).
Our starting point for calculating the requirements for cache memory is
Little’s law, as applied previously inthe result (1.14). The...
... early demotion of sequential data residing inthe cache;
the memory for such data is typically freed long before thedata would have
progressed from the top to the bottom ofthe LRU list. Storage ... much the performance ofthe processor buffers themselves which
complicate the picture developed so far, since their performance can be de
-
scribed by the methods of analysis already discussed. Instead, ... prime indicates the miss ratio inthe combined configuration.
A more interesting configuration is one in which τ
c
< τ
p
. In this environ
-
ment, a “division of labor” becomes possible, in...
... applying (1.26), that the processor miss ratio must be evaluated at the
single
-
reference residency time ofthe storage control cache).
Plugging (1.4) into (1.26), we find that, for reads, inthe ... constant. Inthe region < however,
the plot should show reduced responsiveness, reflecting the reduced exponent
appearing in (1.27).
Also, the transition between the two regions ofthe curve ... virtually the entire line
of reasoning presented inthe previous subsections extends to the case of reads
to a cache, where processor buffers are present. Corresponding to (1 .2 1), we
obtain
(1.28)
where
provided...
... as an
independently executing “daemon” [19], and provides a natural building block
for
I/O performance testing. In addition, it helps bring to life, inthe form of a
concrete example, the hierarchical ... alternative method of characterizing the hierarchical reuse model, which
34
THE FRACTAL STRUCTURE OFDATA REFERENCE
Notes
1 Assumes a track belonging to the 3380 family of storage devices. ... behavior synthetically.
Finally, we illustrate the actual behavior ofthe proposed synthetic requests
through simulation.
1. DESIRED BEHAVIOR
Assuming that a pattern of requests obeys the hierarchical...
... (2.2).
The method of performing the needed random walk can be visualized by
thinking ofthe available tracks as being the leaves of a binary tree, of height
H
max
. The ancestors of any given ... specifically on the most interesting region of interarrival times (those in
the range of 32–512 seconds), all ofthe curves appear to have settled into a
close approximation ofthe predicted ...
obtained by dropping the last two binary digits ofthe number l; and all tracks
have the same great
-
grandparent.
Starting from a given leaf l
i
of the tree, the next leaf l
i+1
is determined...