topic Re: SWAP question in Operating System - HP-UX

SWAP question

Michael Steele_2 — Fri, 06 Jul 2012 14:56:15 GMT

I have two boxes with Ignite warnings about unknown file system type and both are for 2ndary swap. They were created without the -C option and are not contiguous.

What are the ramafications?

Should I remove and recreate?

Re: SWAP question

Bill Hassell — Fri, 06 Jul 2012 17:27:57 GMT

Is the swap volume a raw lvol or filesystem swap? Filesystem swap is really deprecated for today's systems. A raw lvol marked as swap has no filesystem at all, but Ignite should not syntax that (normal) condition. Not sure what -C is referring to. swapon has no -C option. Is your Ignite at least C.7 version?

Re: SWAP question

Michael Steele_2 — Fri, 06 Jul 2012 22:00:06 GMT

Not -C in swapon. -C is for the Contiguous option in lvcreate.

lvcreate -L 850 -n swap -C y -r n /dev/vg02

And contiguous as in , "...the first three lvols of vg00 must be contiguous for the OS to load including lvol2 / primary swap...."

Well, this is 2ndary swap that's been added in because lvol2 wasn't big enough and ignite is flagging it.

Re: SWAP question

Bill Hassell — Sun, 08 Jul 2012 16:02:29 GMT

OK. This is fine but -C is not required.

>> lvcreate -L 850 -n swap -C y -r n /dev/vg02

The contiguous requirement is only for the first 3 lvols in vg00. Secondary swap can be located anywhere, even in a different VG. There are no restrictions where extra swap can be located. This is because the kernel does not need the extra swap during bootup where there are limited addressing methods available. I assume that you have the extra swap listed in /etc/fstab (required in order to be activated at reboot).

Re: SWAP question

Foolqiu — Mon, 09 Jul 2012 13:05:55 GMT

How do you write in /etc/fstab. I mean do you replace vxfs with swap?

Re: SWAP question

Bill Hassell — Tue, 10 Jul 2012 20:01:26 GMT

>> How do you write in /etc/fstab.

The man page for fstab is quite useful.

Here is an example:

/dev/vg05/myswap3 __swap3__ swap defaults 0 0

where: myswap3 is the lvol, __swap3__ is just a placeholder (not a mountpoint), and swap is the type of data on this lvol.

Re: SWAP question

Michael Steele_2 — Tue, 10 Jul 2012 22:29:20 GMT

Bill, Bill, Bill. How the mighty have fallen. How can you argue with JR Ferg?

http://h30499.www3.hp.com/t5/System-Administration/swap/m-p/5346707/highlight/true#M476002

I've always made 2ndary swap contigous so this was a surprise for me to see it here.

Re: SWAP question

Bill Hassell — Wed, 11 Jul 2012 01:31:50 GMT

It may be that only Ignite is syntaxing this since I've created a lot of multiple swap areas on lots of systems without -C. On the other hand, I have never checked to see that the extents were not contiguous -- they may have always been contiguous by accident. As mentioned, the primary swap area must be contiguous to be properly handle during bootup. Dump is a different story. The code for dumping is by necessity quite simple and isolated in order to function without OS assistance...