LaCie 131018 - StorView Snapshot - Mac, User Manual

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Statistics
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15.5 Command Cluster Statistics
To increase performance, the controller can cluster sequential write commands together to create a
larger write command. This results in less commands being sent to the disk drives. Additionally, if
sufficient data is clustered by the controller, then it can perform a a full stripe write for RAID5/50/6 arrays.
This significantly improves performance. In cases where the host does not send a sufficient number of
outstanding writes, writeback cache can be used to delay the write to disk, increasing the likelihood of
clustering more data.
Figure 15–4 Statistics Screen - Command Cluster Tab
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 5/50/6 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 5/50/6 arrays.
Command Cluster Count When the controller clusters a write command, it may cluster
a large number of them together. These statistics record the
average and maximum number of commands the controller
clusters, and also the percentage for each one of these
values.