# Unison Segfaulting

## Bigun

I have two servers:  a production server and a backup server.

I am using unison to backup the production server to the backup server.  I recently upgraded the backup server to a new motherboard and processor (although the processor and motherboard are the same manufacturer, MSI and AMD respectively).  Also the OS partitions on the backup server are now on software RAID-1.

Anyway, the first attempt to run backup last night resulted in a segfault.  I ran the backup manually, and after about two minutes the socket process on the backup server segfaults without fail.  I re-emerged unison with no luck.  Where do I begin to troubleshoot this?

*edit*

The process does not give a lot of information to use either.  The socket server starts:

```
server started
```

I begin syncing directories.  After about two minutes or less, the process dies and displays:

```
Segmentation fault
```

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## Hu

Start by enabling core file generation and checking the callstack of the fault.

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## Bigun

 *Hu wrote:*   

> Start by enabling core file generation and checking the callstack of the fault.

 

 :Shocked: 

Forgive me.... I do not know how to do what you are asking.

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## Bigun

I used strace on the socket process, here is the portion where the process died:

```

fcntl64(7, F_SETFD, FD_CLOEXEC)         = 0

_llseek(7, 0, [0], SEEK_CUR)            = 0

--- {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0xfa297f63} (Segmentation fault) ---

rt_sigaction(SIGSEGV, {SIG_DFL, [], 0}, NULL, 8) = 0

sigreturn()                             = ? (mask now [])

--- {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0xfa297f63} (Segmentation fault) ---

+++ killed by SIGSEGV +++

Segmentation fault

```

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## Hu

Have you read How to get meaningful backtraces in Gentoo?

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