disk I/O

[???_185]

whever I try to proceed bdf command,
disk I/O is being 100%.
the system is using eva5000 for local file system. and This is nfs server is connected with nfs client is using 800G.
How can I decrease DISK I/O?

[RAC_1]

There is no magical way to do it. you need to know what is causing the 100% disk io.

Which file system in particular is getting lots of i/o, more precisely physical io.
glance -i
sar -d 1 4
iostat 1 4

Also if this is nfs server, is everything ok with nfs mounts?? bdf may be having a problem going through nfs mounts and may appear to hang.

[Vibhor Kumar Agarwal]

Have a look at the processes running.

Mounting of various drives form different machines also increases that.

Sort your processes, this might give you an idea.

[Bharat Katkar]

BDF you tell you the disk usgae and not I/O.
For I/O you need to use iostat command.

If it shows high utilisation then you may probably think of:

1. Moving highly utilized lv (pertaining to that disk) to some other underutilised disks.

2. Avoiding unnecessary read/writes to that lv (disk).

Regards,

[Jayasuntar]

Hi,

First of all bdf will gather info about the mounted file system, inclusding nfs and will tell about the usage. When try to access the FS, it might have some problem. Please remove any CD from the system (if it is there , and then try).

Use glance -u,

will tell u which process and whcih disk is high.

Regards

Jay

[Bill Hassell]

bdf (with no options) will be quite slow on a busy system. If disk I/O is already 100%, it is because you are running programs that use the disk. There is nothing wrong with 100% disk I/O unless the programs are wasting I/O time due to poor design. For instance, in a database, lack of working indexes will cause massive I/O as the needed records are serially read from the entire database.

You may need to tune your NFS server in case the usage is excessive. The NFS book by Dave Olker is a good reference.

[AwadheshPandey]

go to link:
http://sunsite.uakom.sk/sunworldonline/swol-08-1999/swol-08-perf.html

Awadhesh