MFS filling up on net4521

[Bill Maas-2]

Hi,

I'm not very familiar with memory issues let alone OpenBSD's MFS memory
allocation/release algorithms, but the following strikes me as being a
bit odd:

net5501:
Filesystem  1K-blocks      Used     Avail Capacity  Mounted on
/dev/wd0a      983486    286662    647650    31%    /
mfs:26509        7855      2913      4550    39%    /var

net4801:
Filesystem  1K-blocks      Used     Avail Capacity  Mounted on
/dev/wd0a      983486    287002    647310    31%    /
mfs:18470        7855      3271      4192    44%    /var

net4521:
Filesystem  1K-blocks      Used     Avail Capacity  Mounted on
/dev/wd0a      496894    424180     47870    90%    /
mfs:22103        7855      5485      1978    73%    /var

All boxes have an MFS partition mounted onto /var. Amount of RAM varies
from (by heart - I'm not sitting next to these boxes right now) 128MB
(net4521) to 512MB (net 5501). The 4521 has the least amount of memory,
that's for sure.

What happens is that the disk usage on the MFS partition stabilizes at
around 40% when I use a log rotating script. But with the same script,
the MU keeps growing on the 4521 towards 100%. A significant part of it
does not seem to be accounted for as actual disk usage:

df -h:
Filesystem  1K-blocks  Used  Avail Capacity  Mounted on
mfs:22103   7.7M       5.4M  1.9M    74%    /var

du -sh /var:
1.8M    /var/

After a reboot it's back to a sane value (~20M). Leaks? Allocation
issues? As said, the net4521 is lowest on RAM.

Or am I staring the Stupid and Obvious right in the eye here?

Bill



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[Brian Candler]

On Sun, Jun 15, 2008 at 08:20:23PM +0200, Bill Maas wrote:

> A significant part of it
> does not seem to be accounted for as actual disk usage:
>
> df -h:
> Filesystem  1K-blocks  Used  Avail Capacity  Mounted on
> mfs:22103   7.7M       5.4M  1.9M    74%    /var
>
> du -sh /var:
> 1.8M    /var/
>
> After a reboot it's back to a sane value (~20M). Leaks? Allocation
> issues?

Something holding one of those files open in /var?
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[Chris Babcock-3]

Brian Candler wrote:

> On Sun, Jun 15, 2008 at 08:20:23PM +0200, Bill Maas wrote:
>> A significant part of it
>> does not seem to be accounted for as actual disk usage:
>>
>> df -h:
>> Filesystem  1K-blocks  Used  Avail Capacity  Mounted on
>> mfs:22103   7.7M       5.4M  1.9M    74%    /var
>>
>> du -sh /var:
>> 1.8M    /var/
>>
>> After a reboot it's back to a sane value (~20M). Leaks? Allocation
>> issues?
>
> Something holding one of those files open in /var?

Yeah, it does sound like deleted inodes being held open.  Anybody know
if LSOF can display open but deleted inodes?

As a test, when one of the boxes gets low, try killing and restarting
all of the processes LSOF displays with resources open on /var, and see
if the utilization changes.

-Chris
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[Chris Babcock-3]

Brian Candler wrote:

> On Sun, Jun 15, 2008 at 08:20:23PM +0200, Bill Maas wrote:
>> A significant part of it
>> does not seem to be accounted for as actual disk usage:
>>
>> df -h:
>> Filesystem  1K-blocks  Used  Avail Capacity  Mounted on
>> mfs:22103   7.7M       5.4M  1.9M    74%    /var
>>
>> du -sh /var:
>> 1.8M    /var/
>>
>> After a reboot it's back to a sane value (~20M). Leaks? Allocation
>> issues?
>
> Something holding one of those files open in /var?

So a quick check of LSOF on on of my systems _does_ show deleted files,
but only in the full listing, not with the +D option.

LSOF output line shows:
dd        16230 cbabcock    1w      REG        9,2 23444104      48146
/home/cbabcock/testfile.txt (deleted)
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