topic Re: Wait Status is Cache in Operating System - HP-UX

Wait Status is Cache

Sagar Sirdesai — Mon, 18 Apr 2011 11:16:46 GMT

Hi
I've 500 GB FS and I'm copying data using pax from this FS to another FS of the same size in the server.

I'm usinng glace to monitor.
I see very less disk I/O and most of the time the process wait status is either Cache or I/O

Please advise if this a desired or needs to fine tuned
Thanks

Re: Wait Status is Cache

Dennis Handly — Mon, 18 Apr 2011 17:29:48 GMT

Copying data is an I/O and cache intensive process.

Re: Wait Status is Cache

Sagar Sirdesai — Tue, 19 Apr 2011 09:24:16 GMT

Thanks Denis for the reply..
Please advise if there is any possiblities to fine any settings to improve the performance of the copy

Re: Wait Status is Cache

James R. Ferguson — Tue, 19 Apr 2011 12:00:09 GMT

Hi:

I have found that subtantial improvement in copy time can be made by temporarily changing the target filesystem mount options to negate caching.

For for data replication use 'pax' [blocking doesn't matter]. During the file copy session, mount the destination filesystem with the options '-o largefiles,nolog,convosync=delay' for the fastest replication. When the copy completes, unmount and remount with normal, protective options, or use the '-o remount' option with the other arguments you need to (re)apply.

Regards!

...JRF...

Re: Wait Status is Cache

Sagar Sirdesai — Tue, 19 Apr 2011 13:44:41 GMT

Many Thanks James,

Please provide some documentation and possible example which explain these options

I know man is the best place to start with.
But if you have docs which explains it in easy words . Please pass it on.

Thanks

Re: Wait Status is Cache

James R. Ferguson — Tue, 19 Apr 2011 13:59:57 GMT

Hi (again):

> I know man is the best place to start with.

Indeed, see the manpages for 'mount_vxfs(1M)'. Strangely, this is missing from the 11.31 manpages (at least online), so use:

http://bizsupport.austin.hp.com/bc/docs/support/SupportManual/c01921587/c01921587.pdf

Regards!

...JRF...