So Marcy, if you have 275GB of VDISK defined, what do you define for total page
space for your VM? Just curious. I am almost always in disagreement
with our VM guy on our configuration, but I'm getting ready to revisit VDISK
swap because we're on a new machine with more memory. The more
information I have on 'real companies' and their configurations the less
intractable he seems to be.
-J
Marcy Cortes <[EMAIL PROTECTED]>
Sent by: Linux on 390 Port
<[email protected]>
To
[email protected]
cc
12/03/2007 07:30 PM
Subject
Re: Is
275GB of VDISK stupid?
Please respond to
Linux on 390 Port <[email protected]>
I haven't added it all up, but we do it that way and would have to be either
right around 275G if not over.
One thing to look out for is the vm.swappiness setting. Seems that on SLES
9 (latest kernel) some virtual machines have a tendency to just keep writing
more and more to swap and never free up those pages in vdisk until the
process is stopped. We had production machines march through all their
space and then java core dump :(. Used page space was also growing too
quickly without it. Yes, swapoff/swapon would free up those pages (but the
structures would still exist in VM).
Setting kernel parameter vm.swappiness=20 seemed to prevent that. Don't ask
me why... It just does :) (no time to go read the code and truly understand
that)... The default is 60.
PS. We use mod 3's for paging and mod 27's mostly for everything else. 9's
seem kind of useless after you build a file system on them and only have
like 6-something Gig left.
Marcy Cortes
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