Todd Denniston wrote:
Simon Slater wrote, On 03/10/2008 06:37 PM:
G'day all,
This is an inconvenience that I would like to get to the
bottom of. I
have a PII 233MHz 512 MbRAM running FC6. All is fine until swap reaches
about 25% used then the system hangs. It will run for days with the
swap at 10-15%. My first thought was to run badblocks to see if that
was the problem, since it is an old drive, but couldn't find the swap
device with mount.
Been there, done that.
WARNING: before using badblocks in full rw mode on swap space,
remember two things:
1) some how you would have to convince mkswap to retake what ever
label is being used in /etc/fstab, or you would need to use a new
label/device name in /etc/fstab.
2) don't be using it for swap while checking it. :)
/sbin/swapon -s
will display which partitions/files are being used in the system for
swap.
/sbin/swapoff -a
will turn swap off. probably should shut down any programs down that
you don't need so that you can get under 512MB, then badblocks (with
full read/write test and re-`mkswap -c` on it, or Use non-destructive
read-write mode) sounds like a reasonable thing.
If you find a single bad block, you should really be looking for new
hardware.
I have done the thing where you partition around the bad blocks, but
it only buys you a little time.
If I understand the man-page for mkswap the -c will print the bad
block locations, it says nothing of setting up swap to avoid them.
Here's a thought, create a swap *file*, at least as big as your swap
partition if you can, but at least as big as necessary to hold what is
in swap now. Enable it with "swapon pathname".
*then* turn off your old swap partition. *then* check it for bad blocks
by re-running mkswap on it with the -c option. Now you will be
protected in case in case you *can't* swap everything back in.
My questions are: what would cause this system to hang when the swap
file is used?;
[from experience I know] Bad blocks in swap cause errors that look
_just_ like failing ram. That is, programs just die, system locks up
in weird ways.
where is the swap file?;
Most times it is a swap partition, `/sbin/swapon -s` or `cat
/proc/swaps` will help here.
if in the VG, how do I umount it
to run badblocks?
/sbin/swapoff
Here is some output that may be useful.
Thanks.
Good luck.
