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

[Brian J. Murrell]

On Tue, 2008-04-29 at 09:05 -0700, Kilian CAVALOTTI wrote:
> Hi Brian,

Hi Kilian,

> I was precisely wondering if it was possible to use a file residing on a 
> Lustre filesystem as a swap file.

There certainly has been some historic use and testing of swap on
Lustre.  I'm not sure what it's current state is TBH.  The last bug in
bugzilla I can find about swap and Lustre is bug 5794/5749/5188 filed
over two years ago (however updated just recently) in reference to some
of our regression testing we do with swap on Lustre.

It seems the final outcome is that it has been flagged (just today in
fact) as a 1.6.6 blocker.  The timing is absolutely uncanny!

> # 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?

I would think not, no.  There is some reference in bug 5188 that we only
test it for "real/remote OSTs" and "non-TCP" interconnects.  I wonder if
either of those match your situation.  You might file a bug about it,
including the usual data -- syslog from the client you did the swapon on
for example.  A (-1) debug log from the client right at the time of the
swapon would probably be useful.

b.

-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: This is a digitally signed message part
URL: <http://lists.lustre.org/pipermail/lustre-discuss-lustre.org/attachments/20080429/f5fdd9e2/attachment.pgp>