Gateway 840 VT-100, Руководство пользователя

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Chapter 8: Statistics
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Statistic Description
Write Cluster Rate This is the percentage of the number of write commands
that are part of a cluster versus the total number of write
commands that have been issued. This gives an
indication of the sequential nature of the data access
pattern from the host and of the performance of the
writeback cache.
RAID 5/50 Partial Command
Cluster Rate This is the percentage of the number of clustered
commands that wrap around the end of a stripe versus
the total number of clustered commands. This gives an
indication of the alignment of the operating system.
RAID 5/50 Full Stripe Write
Rate This is the percentage of the amount of data that is
written as a full stripe write versus the total amount of
data written. This gives an indication of the sequential
nature of the data access pattern from the host and of
the performance of the writeback cache, for RAID 5/50
drive ranks.
Command Cluster Interval In determining whether to cluster write commands, the
controller will search back in the command queue
whenever it receives a new write command. In a multi
threaded operating system, commands from each
thread can be interspersed with commands from
another thread. This requires that the controller not just
check the immediately previous command. The
controller will search back for a number of commands,
to try to determine if the new command is exactly
sequential to any one of these previous commands. If
it is, then the controller determines that it can cluster
these commands.
These statistics record the average and maximum
number of commands the controller must search back
for when it finds a sequential command match and the
percentage for each one of these values.
Command Cluster Count When the controller clusters a write command, it can
cluster a large number of them together. These
statistics record the average and maximum number of
commands the controller clusters and the percentage
for each one of these values.