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Yet another swap question--looking for advice for rx6600 server

 
S. Ney
Trusted Contributor

Yet another swap question--looking for advice for rx6600 server

We are going to be adding an additional 16Gb of ram to two of our rx6600's. We currently have 32Gb of RAM and 32Gb of swap space configured. The swap is interleaved across two disks.. (swapinfo -tam and paste from fstab below)
Mb Mb Mb PCT START/ Mb
TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME
dev 16384 284 16100 2% 0 - 1 /dev/vg00/lvol2
dev 16384 285 16099 2% 0 - 1 /dev/vgora/lvswap
reserve - 15595 -15595
memory 31137 8628 22509 28%
total 63905 24792 39113 39% - 0 -

/dev/vgora/lvswap ... swap pri=1 0 0

I cannot ignite to resize lvol2. The SAN admins do not want SAN disks being used for swap and in addition only assign 100Gb sized luns as the smallest allotment. There is room in the vg that has the lvswap lvol however lvswap's extents are at the top of the disk. (PE 00000)

So as I see it my options are to re-organize the extents on the disk(s) where vgora resides or create a second lvol for swap in vgora. I realize neither situation is ideal however I'd like some expert advice as to which option would be less damaging. I'm leaning towards adding the second lvol option with a different priority but still open to suggestions.

7 REPLIES
Dennis Handly
Acclaimed Contributor

Re: Yet another swap question--looking for advice for rx6600 server

Why do you think you need more swap?
You don't to match RAM with swap, RAM helps all by itself.
Torsten.
Acclaimed Contributor

Re: Yet another swap question--looking for advice for rx6600 server

If you want to use the swap as a dump device, you need this space equal to the RAM size.
But this decision is up to you ...

Hope this helps!
Regards
Torsten.

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S. Ney
Trusted Contributor

Re: Yet another swap question--looking for advice for rx6600 server

I'm not sure that the additional 16Gb of RAM we are getting are going to be enough. We are also getting an additional processor for the server however there are disk io issues as well. It's a case of the server was designed to do X but in reality has to do XYZ. I've seen in glance memory use in the 80's & 90's and have seen heavy page out's, in's in vmstat. The system is running oracle 11g with a very large sga.

I was not planning on using the new swap as dump but was under the impression that swap space had to be greater than or equal to system memory.
Dennis Handly
Acclaimed Contributor

Re: Yet another swap question--looking for advice for rx6600 server

>but was under the impression that swap space had to be greater than or equal to system memory.

Probably only if you have a small memory system or you want to use it as dump.

Or you want to run lots of applications that allocate sparse memory so that reserve swap is more than allocated.
hvhari
Esteemed Contributor

Re: Yet another swap question--looking for advice for rx6600 server

If the memory is sufficient enough for your application, you can enable pseudo swap.

For dump , you can configure crashconf in hpux to enable specific portions of memory to be dumped or use compressed dump to reduce the size of dump.
Refer http://bizsupport2.austin.hp.com/bc/docs/support/SupportManual/c01919999/c01919999.pdf
Regards,
Hari

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S. Ney
Trusted Contributor

Re: Yet another swap question--looking for advice for rx6600 server

Thanks to all who have responded,

I'll run it by management that I'd like to keep swap sized as is since I'm not planning on using it as dump.
S. Ney
Trusted Contributor

Re: Yet another swap question--looking for advice for rx6600 server

Going to keep swap configured as is.