STATSΒΆ
STATS Displays the system performance statistics.
This command will display the performance statistics for the host ports, disk channels, and the cache memory. The command will show the read and write performance of each of the host ports. Read hits shows the percentage of read I/O requests where the data was already in the cache. Prefetch hits shows the percentage of read I/O requests where the data was already in the cache because of prefetching. Prefetches shows the percentage of host read I/O requests to the disks which are due to prefetching. The bottom of the screen shows the read and write performance of the disks. Disk pieces shows the total number of disk I/O requests from the host ports. BDB pieces is the number of host I/O blocking deblocking requests. Cache writeback data shows the percentage of the cache which contains writeback data which must be written to the disks. Cache rebuild data shows the percentage of the cache in use for rebuild operations, and Cache data locked shows the percentage of the cache which is locked by the locked LUNs.
- CLEAR
- This parameter resets all the statistics back to zero.
- DELAY
- This parameter displays a histogram of the time it takes for the host and disk I/O requests to complete. The disk queue delay includes the time the disk commands were queued up waiting to be sent to the disks.
- DISKPIECES
- This parameter displays a histogram of the number of transfer pieces per disk command by disk command type. The system will combine several host I/O requests into a single disk I/O request. This histogram shows how often this is occurring.
- DISK|DISK=[t|c|tc] [CLEAR
- This parameter displays a histogram of which disks in the system have taken an unusually long time to complete an I/O request. The count is incremented for a disk if the disk took longer than the other disks to finish an I/O request. This command is used to determine if a disk in the array is slowing down the system performance. Normally all the disks in a tier should have similar counts. A disk with a significantly higher count indicates that the disk may be slower or it may have problems. Optionally a specific tier (‘t’), channel (‘c’) or drive (‘tc’) can be used to narrow the scope. The optional CLEAR can be used to clear (instead of displaying) these statistics on a drive, channel, tier or whole system basis.
- DUAL
- This parameter displays the statistics for the dual mode messages.
- HOSTDELAY
- This parameter displays a histogram of the time delay between when a data transfer is set ready and the host interface completes the transfer.
- INTERVAL=x
This parameter determines how many seconds the system will wait before displaying the repeating statistics information. This parameter is not saved. The valid range for ‘x’ is 1 to 60 seconds.
Default is 2 seconds.
- LENGTH
- This parameter displays a histogram of the length of the host I/O requests in 16 KiB intervals.
- OFFSET
- This parameter displays a histogram of the offset of the host I/O requests into the cache segments. 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.
- REPEAT=MAIN|MBS|IOS|OFF
Allows the user to enable/disable the repeating statistics display, where:
- MAIN - display the normal STATS display.
- MBS - displays MiB/s.
- IOS - displays IO/s.
- OFF - turns off the repeating displays.
- SAMPLES=x
- This parameter allows the user to specify how many times the repeating statistics display should repeat before turning off. Setting this value to a non-zero value will automatically enable the repeating statistics. The valid range for ‘x’ is 0 to 65535 samples. Default is 0.
- TIERDELAY|TIERDELAY=[t|c|tc] [CLEAR]
This parameter displays a histogram of the time it takes for the disk I/O requests to complete for all the disks in the specified tier, ‘t’, or specified channel, ‘c’, or specified drive, ‘tc’‘. If nothing is specified, then all valid tiers will be displayed.
The CLEAR option will allow for selective clearing of these statistics.The optional CLEAR will allow for selective clearing (instead of displaying) of these statistics.
- TIERLENGTH|TIERLENGTH=n
- This parameter displays a histogram of the length of the disk I/O requests for each tier in 8 KiB intervals.