APC SGI 15000 RAID - Manual (Page 80)

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STATS OFFSET displays a histogram of the offset of the host I/O requests into the cache segments
( Figure 3–40 ) . Host I/O requests with offsets that are not in the 0x0 column may require blocking/
deblocking which can slow down the performance of the system.
Figure 3–40 Host Command Offsets Screen
STATS REPEAT=OFF|MBS|IOS allows you to enable/disable the repeating statistics display where
MBS displays MB/s, IOS displays IO/s, and OFF turns off (both) the repeating displays.
3.3.4 Resources Allocation
Background Format/Rebuild Operations
Format and rebuild operations are background processes; their rates can be adjusted to minimize their
impact on system performance.
Figure 3–41 Displaying the Current Rebuild Parameters
TIER displays the current rebuild parameter settings for the system (Figure 3–41).
The TIER DELAY parameter controls the amount of system wait time before rebuilding the next chunk
of data. This parameter slows down the rebuild and format operations so they will not affect the
performance of the system. TIER DELAY=0 will remove many delays so the rebuild and format
operations will go as fast as possible, but this could significantly affect the performance of the system.
NOTE : A delay value less than 1 (<1) is not recommended.
Host Command Offsets
15000 [1]: stats offset
x0 x1 x2 x3 x4 x5 x6 x7
0 720943 8 11 5 0 2 0 343AAD2
8 3FE8E9 5 10 1 0 2 0 3486F35
10 42754D 3 6 0 0 4 1 39B0635
18 4AA571 1 4 2 0 6 0 40677A9
Most commands should be in column 0 or 4 for the best performance.