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.

15000 [1]: stats offset

 

 

 

 

 

 

 

 

 

Host Command Offsets

 

 

 

 

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.

Figure 3–40Host Command Offsets Screen

STATS REPEAT=OFFMBSIOS 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.

3.3.4Resources 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 3–41Displaying 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.

66

007-5510-002

Page 80
Image 80
APC 15000 RAID manual Resources Allocation, Background Format/Rebuild Operations