L1000 w/mirroring. Questions about changing/mirroring primary swap.

[Dee_3]

I have an L1000 system with 1 Gig of memory that is mirrored. When the system was built, the config file was defined to use MEMORY * 2 with an upper limit of 1024 for primary swap. The mirroring software was then installed and configured, and the primary swap /dev/vg00/lvol2 on this system was not mirrored at that time. The mirrored disk has been setup as bootable too. I was asked to extend one of the other mirrored lvols on this system. I am concerned that when I look at this system it is showing that /dev/vg00/lvol2 is LV Size (Mbytes) 4096 with Used PV 1. My questions are: 1. Can I reduce primary swap on this system to allow me to further extend the other file system without rebuilding it, as I don't feel I need that much swap defined? 2. And, should the primary swap be mirrored since my mirrored disk has been setup as bootable too, in the case where there would be a problem with the primary and we boot on the mirrored disk for a time? Thanks.

[Patrick Wallek]

Yes you could reduce your primary swap. Before you do, check and see if you are utilizing your swap space, and if so, how much. I would not try to reduce your primary swap while the system is up and running in multi-user mode. Bad things could happen. I would boot into single-user mode and proceed from their.

YES, you should definitely have your primary swap mirrored. If you lose the disk that primary swap is on, then your system will essentially cease to function because you no longer have ANY swap space available.

When you mirror your vg00 disk(s), mirror ALL LVs within vg00.

[Sridhar Bhaskarla]

It is not a good idea to play around with swap. If you get sometime, it's better to create make_recovery tape and then rebuild the system with new sizes.

If you want to proceed your way, you need to lvrmboot -s /dev/vg00/lv_for_swap.

On the mirror disk, create mirror for stand, then create a logical volume of required size for the swap and then mirror the other logical volumes.

Now use lvlnboot -s /dev/vg00/other_swap to update the swap area.

Reboot the system from the mirror disk to get the new swap in effect.

Once it is working, you can re-establish mirrors to the primary disk referencing from the mirror disk.

Note: please prepare a make_recovery tape and verify it before you do anything.

-Sri

[Jon Mattatall · Accepted solution]

Hi there...
The short answer is yes, you can. Others here are far more qualified to tell you if you should....but -

I had to do this exact same task - reduce primary swap, extend mirrored lvols, and restore continuity.
(I call it defrag, there's probably a more correct term)

Attached is the doc I made up for this, and it did work. Ignore my specific values, they applied to my server, and do this from the console, NOT telnet.

Jon