Hi,

28.05.2008 00:52, Andy Shellam wrote:

Ah, another Nagios-user mailing list person :-)

> Hi,
> 
> I have a virtual server which I'm trying to backup with Bacula 2.2.8, 
> but it keeps crashing the machine.  The machine has 256MB RAM allocated, 
> and 512MB swap space (minimal specs I know but it doesn't do a lot!)
> 
> While monitoring the server using top, when the backup starts the free 
> memory drops steadily from 200MB free down to 2MB, then hovers around 
> 2-5MB.  The swap space isn't touched.  5 minutes later the machine dies 
> with a memory allocation error, still with all 512MB swap space free.
> 
> My server provider tells me this is expected, that because it's a single 
> process eating into all the RAM, the server can't swap it.  Is this 
> true?

Hmm... I'm not sure. Might be. But that shouldn't crash the whole 
machine. If the FD gets killed - ok. But nothing worse should happen IMO.

If that's and old linux kernel the behaviour you see might be 
expected; newer ones tend to kill some processes before things get 
really dramatic (OOM killer as "Out Of Memory").

>  I have 2 other servers with the same provider, identical in every 
> way except they have 512MB RAM and 1GB swap, and they both backup just 
> fine.
> 
> Another thing that is different is that on this troublesome machine, the 
> bacula startup script (/usr/local/bacula/etc/bacula start) starts 3 
> bacula-fd processes, but on all my other machines it only starts 1.  Is 
> there any reason for this?

Are these the same OS versions?

I suspect that on the small machine an older version of the (linux) OS 
or the ps program is running.

The thing is that threads (aka Light-weight Processes) are sometimes 
displayed as spearate processes, and sometimes not, depending on the 
software you use.

For example, on a reasonably new OS:

arno@elf:~> ps -lfLC bacula-fd
F S UID        PID  PPID   LWP  C NLWP PRI  NI ADDR SZ WCHAN  STIME 
TTY          TIME CMD
1 S root      4718     1  4718  0    2  76   0 - 11968 -       2007 ? 
        00:00:21 /usr/sbin/bacula-fd -c /etc/bacula/bacula-fd.conf
1 S root      4718     1  4719  0    2  76   0 - 11968 322561  2007 ? 
        00:00:04 /usr/sbin/bacula-fd -c /etc/bacula/bacula-fd.conf

This displays the threads separately.

arno@elf:~> ps -lfC bacula-fd
F S UID        PID  PPID  C PRI  NI ADDR SZ WCHAN  STIME TTY 
TIME CMD
1 S root      4718     1  0  76   0 - 11968 -       2007 ? 
00:00:21 /usr/

This does not, but on older software it would display two processes.


> On troublesome server (with backup job disabled):
> 
> root ~ # ps aux|grep bacula-fd
> root      3160  0.0  0.5  13200  1392 ?        Ss   21:55   0:00 
> /usr/local/bacula/sbin/bacula-fd -u root -g root -v -c 
> /usr/local/bacula/etc/bacula-fd.conf
> root      3162  0.0  0.5  13200  1392 ?        S    21:55   0:00 
> /usr/local/bacula/sbin/bacula-fd -u root -g root -v -c 
> /usr/local/bacula/etc/bacula-fd.conf
> root      3163  0.0  0.5  13200  1392 ?        S    21:55   0:00 
> /usr/local/bacula/sbin/bacula-fd -u root -g root -v -c 
> /usr/local/bacula/etc/bacula-fd.conf
> 
> On other servers (with backup job live as normal):
> root ~ # ps aux|grep bacula-fd
> root     11114  0.0  0.3  27208  1628 ?        Ssl  19:26   0:00 
> /usr/local/bacula/sbin/bacula-fd -u root -g root -v -c 
> /usr/local/bacula/etc/bacula-fd.conf

See the "l" in the process state? From my ps(1) man page:

> l    is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)


...

Arno

-- 
Arno Lehmann
IT-Service Lehmann
www.its-lehmann.de

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