Re: Out of memory in CIFS leads to database crash

On Tue, Jan 7, 2014 at 2:03 AM, Umesh Kirdat <umesh.kirdat@yahoo.com> wrote:

> Hello All,
>
> In our setup under heavy load (too many client performing updates) we have
> observed the underlying CIFS module runs out of memory and the database
> crashes or goes in recovery mode.
>
> Nov 28 09:17:32 ng78 kernel: CIFS VFS (1006f1e5e,pid=19342): Error in Open
> = Out of memory<3> ISVS(0615,i=96) ro nOe u fmoy<3> CIFS
> VFS(1006f16,pid196) ror i pn u fmmor
> Nov 28 09:17:32 ng78 postgres[19342]: [10-1] 192.168.20.78 19342
> 2013-11-28 09:17:32.882 PST ERROR: could not open file "base/16384/16794":
> Cannot allocate memory
> Nov 28 09:17:32 ng78 postgres[19342]: [10-2] 192.168.20.78 19342
> 2013-11-28 09:17:32.882 PST STATEMENT: select
>
> The physical memory on the machine is 64 GB
> Postgres version 9.0.4
> Hardware is 64 bit
>
> I wish to know why is the database crashing if the file open fails? Why
> can't it handle it gracefully by rolling back the transaction?
>

Based on the section of the log you are showing, it looks like it did just
roll back the transaction.  A crash should be showing you PANIC messages,
not just ERROR.  Is there more to the log than you are showing?  If you are
logging over CIFS as well, perhaps the PANIC messages are getting lost
because they can't be logged.

I don't think that running with the data directory on CIFS is supported.  I
certainly wouldn't be brave enough to do that with data I care about.

Cheers,

Jeff