Administrator Guide

Table 28. Historical performance (continued)
System component Graph Description
Tier Number of Page Moves In Number of pages moved into this tier from
a different tier.
Tier Number of Page Moves Out Number of pages moved out of this tier to
other tiers.
Tier Number of Page Rebalances Number of pages moved between disk
groups in this tier to automatically load
balance.
Tier Number of Initial Allocations Number of pages that are allocated as a
result of host writes. This number does not
include pages allocated as a result of
background tiering page movement.
(Tiering moves pages from one tier to
another, so one tier will see a page
deallocated, while another tier will show
pages allocated; these background moves
are not considered “initial allocations.”)
Tier Number of Unmaps Number of 4-MB pages that are
automatically reclaimed and deallocated
because they are empty (they contain only
zeroes for data).
Tier Number of RFC Copies Number of 4-MB pages copied from
spinning disks to SSD read cache (read
flash cache).
Tier Number of Zero-Pages Reclaimed Number of empty (zero-filled) pages that
were reclaimed during this sample period.
Updating historical statistics
The Performance topic can show historical performance statistics for the following types of components: disks, disk groups, and virtual
pools and tiers. By default, the newest 100 samples are shown. For more information about performance statistics, see About
performance statistics.
Update displayed historical statistics
1. Display a historical statistics graph as described in Viewing performance statistics.
2. Select Action > Update Historical Statistics.
The Update Historical Statistics panel opens and shows the default count value of 100.
3. To specify a count, in the Count field enter a value in the range of 5 to 100 and click OK.
4. To specify a time range, perform the following:
• Select the Time Range check box.
• Set date/time values for the starting and ending samples. The values must be between the current date/time and 6 months in the
past. The ending values must be more recent than the starting values.
NOTE: If you specify a time range, it is recommended to specify a range of 24 hours or less.
• Click OK.
In the Historical Data area of the Performance topic, the Time Range values are updated to show the times of the oldest and newest
samples displayed. The graph for the selected components is updated.
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Working in the Performance topic