> We have a DB running firebird 2.1.
> Its version LI-V6.3.1.17910 Firebird 2.1.
>
> Its running on a Debian Linux with 12 Gb RAM.

What FB binaries do you use - from Debian distribution or our official ones ?

...

> Last time we had this was just 3 days ago.
> We retrieved this from linux:
>
>
> ===========
> 14:36:07 localhost kernel: fbserver[18628]: segfault at 00002aaacbf24af2 rip 00000000005150f3 rsp 0000000041800d70 error 4
>
> Core was generated by `/opt/firebird/bin/fbserver'.

...

> ===========
>
> I don't know if this can be of any use.

Unfortunately, this info is not correct. It could happen if debug info is not corresponding
to the binaries.

BTW, why do you use SuperServer and not ClassicServer ?

I recommend you to upgrade to just released FB 2.1.3 and ensure you have correct
files with debug-info.

Regards,
Vlad