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Wait Status is Cache

 
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Sagar Sirdesai
Trusted Contributor

Wait Status is Cache

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
5 REPLIES 5
Dennis Handly
Acclaimed Contributor

Re: Wait Status is Cache

Copying data is an I/O and cache intensive process.
Sagar Sirdesai
Trusted Contributor

Re: Wait Status is Cache

Thanks Denis for the reply..
Please advise if there is any possiblities to fine any settings to improve the performance of the copy
James R. Ferguson
Acclaimed Contributor
Solution

Re: Wait Status is Cache

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...

Sagar Sirdesai
Trusted Contributor

Re: Wait Status is Cache

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
James R. Ferguson
Acclaimed Contributor

Re: Wait Status is Cache

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...