[Lustre-discuss] Swap on Lustre (was: Client is not accesible when OSS/OST server is down)

[Kilian CAVALOTTI]

Hi Brian,

On Tuesday 29 April 2008 07:53:01 am Brian J. Murrell wrote:
> Unless you are using Lustre for your root and/or usr filesystem
> and/or for swap, Lustre should not hang a machine completely.

I was precisely wondering if it was possible to use a file residing on a 
Lustre filesystem as a swap file. I tried the basic steps without any 
success.

On a regular ext3 fs, no problem:

/tmp # dd if=/dev/zero of=./swapfile  bs=1024 count=1024
10240+0 records in
10240+0 records out
/tmp # mkswap ./swapfile
Setting up swapspace version 1, size = 104853 kB
/tmp # swapon -a ./swapfile
/tmp # swapon -s
Filename                       Type            Size    Used    Priority
/dev/sda3                      partition       4096564 204     -1
/tmp/swapfile                  file            102392  0       -2

But on a Lustre mount:

# cd /scratch
/scratch # grep /scratch /proc/mounts
10.10.50.2 at o2ib:/scratch /scratch lustre rw 0 0
/scratch # dd if=/dev/zero of=./swapfile  bs=1024 count=1024
10240+0 records in
10240+0 records out
/scratch # mkswap ./swapfile
Setting up swapspace version 1, size = 104853 kB
/scratch # swapon -a ./swapfile
swapon: ./swapfile: Invalid argument

Is that expected?

Thanks,
-- 
Kilian