How to Check Disk Activity (sar -d)
Display disk activity statistics with the sar -d command.
$ sar -d 00:00:00 device %busy avque r+w/s blks/s avwait avserv 01:00:00 fd0 0 0.0 0 0 0.0 0.0 |
The table below describes the disk devices activities reported by the -d option. Note that queue lengths and wait times are measured when there is something in the queue. If %busy is small, large queues and service times probably represent the periodic efforts by the system to ensure that altered blocks are written to the disk in a timely fashion.
Table 36-10 Output from the sar -d Command|
Field Name |
Description |
|---|---|
|
device |
Name of the disk device being monitored |
|
%busy |
Percentage of time the device spent servicing a transfer request |
|
avque |
The sum of the average wait time plus the average service time |
|
r+w/s |
Number of read and write transfers to the device per second |
|
blks/s |
Number of 512-byte blocks transferred to the device per second |
|
avwait |
Average time, in milliseconds, that transfer requests wait idly in the queue (measured only when the queue is occupied) |
|
avserv |
Average time, in milliseconds, for a transfer request to be completed by the device (for disks, this includes seek, rotational latency, and data transfer times) |
Examples--Checking Disk Activity
This abbreviated example illustrates the sar -d output.
$ sar -d
SunOS venus 5.8 Generic sun4u 09/07/99
00:00:00 device %busy avque r+w/s blks/s avwait avserv
01:00:00 fd0 0 0.0 0 0 0.0 0.0
nfs1 0 0.0 0 0 0.0 0.0
sd0 0 0.0 0 0 0.0 39.6
sd0,a 0 0.0 0 0 0.0 39.6
sd0,b 0 0.0 0 0 0.0 0.0
sd0,c 0 0.0 0 0 0.0 0.0
sd0,f 0 0.0 0 0 0.0 0.0
sd0,g 0 0.0 0 0 0.0 0.0
sd0,h 0 0.0 0 0 0.0 0.0
sd6 0 0.0 0 0 0.0 0.0
|
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