[erlang-questions] Mnesia could not write core file: system_limit

Valentin Micic <>
Wed Dec 9 08:58:05 CET 2009


Just a wild guess... could it be that you're running out of available file
descriptors? The error indicates that you cannot open a log file, which may
be caused by this.

V/

-----Original Message-----
From:  [mailto:] On
Behalf Of Slobodan Miskovic
Sent: 09 December 2009 02:54 AM
To: Erlang-Questions Questions
Subject: [erlang-questions] Mnesia could not write core file: system_limit

Hi all, one of our nodes just popped up the following error:

Mnesia(): ** ERROR ** (could not write core file:
system_limit)
 ** FATAL ** Cannot open log file "/var/mnesia/invoice_item.DCL":
{file_error, "/var/mnesia/invoice_item.DCL", system_limit}

I naively tried mnesia:start() only to have the same error repeat but
for a different table.

Restarting the whole node it now seems ok (error hasn't popped up again)
but...

Problem is that it seems data is now missing from at least one of those
tables. I have made a backup of the whole mnesia after the second
failure, but I don't suppose that data in there somewhere.

1. What has caused this? There is plenty of space left on the device,
process was running as root, ulimit reports unlimited.

2. Is the data really gone? I have enough information elsewhere to
reconstruct the data, but would like to know where it has gone.

3. How to prevent this from happening again? Periodic backups would not
help with this as I can not afford to loose data since last backup even
if I was to do 1hr intervals. Would running another node on another
system be assurance enough? 

I find it very strange that some data would get dropped (about 10k
records out of 85k record table), is it a sign of a mnesia bug or is
this something I should anticipate and work around?

Some potentialy usefull System Info:
- Erlang R12B4 
- about 200 tables, 50% sets 50% bags, both ram and disc copies for each
table
- node takes about 1.2GB ram when data is loaded (I understand there is
2GB per table limit, or am I misguided)
- du -sh /var/mnesia/
343M    /var/mnesia/

- Filesystem            Size  Used Avail Use% Mounted on
/dev/md/1             233G   49G  184G  22% /

- Slackware Linux 2.6.24.5-smp #2 SMP Wed Apr 30 13:41:38 CDT 2008 i686
Intel(R) Pentium(R) Dual  CPU  E2200  @ 2.20GHz GenuineIntel GNU/Linux

- node did not generate erl_crash.dump as I brought it down via shell
q(). The only trace I have is the error above and subsequent error
reports of calls to mnesia failing {aborted, {node_not_running...


Any help and pointers are highly appreciated.

Thanks!
Slobo



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