sar -d 2 6

[Jeff Hagstrom]

device %busy avquer+w/sblksavwaitavserv
c2t6d0 1.50 0.50 1 16 0.42 15.79
c2t5d0 1.50 0.50 2 32 0.57 16.48
c0t0d0 100.00 0.50 48 760 4.63 41.71
Device c0t0d0 is very busy. Is there any way to find why? What is causing that device to be so busy?

[G. Vrijhoeven]

Hi,

Check vgdisplay -v to see which vg the disk belongs to. This will give you some idea. vg00 can be swap vg01 ( dbase ?)
If you have installed glance/gpm you can view I/O and search for a process with havy i/o.

HTH,

Gideon

[Paula J Frazer-Campbell]

Jeff

Once you check which vgs are using it fuser can also come in handy.

Paula

[Hein van den Heuvel · Accepted solution]

I'll attach a little perl script to massage the verbose vgdisplay output into a more dense and nicer (IMHO :-) overview. Sample output in the same attachment (the forum display destroys column based terminal output).

Enjoy,
Hein.

[Sridhar Bhaskarla]

Hi,

avserv is 41.71 which is in milli seconds. This isn't a good number if you are looking for performance.

Try 'pvdisplay -v /dev/dsk/c0t0d0' and see the details.

If you have glance you will know more details.

What kind of disk subsystem do you have?.

-Sri

[Jeff Hagstrom]

I don't have glance. What in the pvdisplay should I look for that would tell me why this device is running very slowly?

[Sridhar Bhaskarla]

Jeff,

pvdisplay will show you the logical volumes in that device then you can find the corresponding mount points hence the usage.

If you don't have glance, it is tough to find what is causing the issue. However, an average service time of 41.71 is actually calculated from the disk subsystem. It's the time it took on the average for an IO request to get serviced. We would need more details.

1. How big is this disk?. How many logical volumes are there in it and what type of activity they do.
2. What is the disk subsystem?

-Sri

[Jeff Schussele]

Hi,

You'll be looking for what LVs are on this disk - i.e. is swap on the disk & it's being pounded because you've run out of memory.

And under the status cloumn that all PEs are current or free & none stale which could indicate a bad spot on the disk.

Rgds,
Jeff

[Pete Randall]

c0t0d0???? Are you sure this isn't a CD drive? What does ioscan tell you about it?


Pete