swap space on sg volume group.

[Ian Killer_1]

Hi SG experts...

I need swapspace. Ideally I want to increase the swap in the root vg, but am a little space restricted. It's a two node cluster with 1 package on each node.

I want to know what the implications would be of creating secondary filesystem swap on an vg that moves with a package. Has anyone done it?

Ian

[Dietmar Konermann · Accepted solution]

Since there is no swapoff command you would no longer be able te deactivate the VG without rebooting.

Not a really good idea, I believe.

[Ashwani Kashyap]

Ideally a secondary device swap on both the nodes is preffered .

Since swap are local to a node , I am not sure failing over a swap is a good idea . Any way since the file system is active exclusively on one node , how would you turn on the FS swap on the other node .

Also note that swap has to be contiguous in allocation .

[Martin Johnson]

Besides not being able to deactivate the package, you will negatively affect performance of your application when you start swaping, especially if your application is I/O intensive.

HTH
Marty

[Ian Killer_1]

Excellent. I thought it might be ugly. Thanks all. It's an lp printing cluster so no super heavy io.
Cheers...

ian

[Jeff Schussele]

Hi Ian,

Nope...no way...

I would certainly NOT advise you do this.
Swap has to ALWAYS be local to the box.

Add a VG/LV to the system someway/somewhere that will not switch.

Rgds,
Jeff

[A. Clay Stephenson]

This will not work but the first question you should ask is "Do I need the swapspace?". Are you paging out now? The old rules about 2x-3x memory for swap space almost never apply these days. I often run very large systems with only 512MB of primary swap and that's it.

[Ian Killer_1]

Hey A. Clay...

Sorry.. I couldn't resist.
LIkewise I've only got 512mb swap. I was definitely swap we ran out of though. "Unable the fork: no space". We just have 3000+ printers and we run lpstat's on them every 5 minutes. lpstat and lpsched both use 3+mb of virtual memory. Thanks.

[Dietmar Konermann]

Is kernel the tunable swapmem_on set to 1? Of course you need lots of "real" swap otherwise.

[Ian Killer_1]

Yep.