zfs: allocating allocated segment

[Peter Schuller]

> I'm running a File server with zfs, 64 Bit, 4 GB Ram and RELENG_7. Two days 
> ago i uploaded a file via ftp to the server and the server is crashing. After 
> reboot FreeBSD can't import the zfs-pool. There is a kernel-message:
> 
> panic: Solaris(panic): zfs: allocating allocated 
> segment(offset=123456... size=74)
> 
> cpuid = 0
> Uptime: 14m22s
> panic: bufwrite: buffer is not busy???
> 
> Now i try to import the zfs-pool with a recent 8.0-current but with the same 
> result. It's very important to me to access the pool, so did you have some 
> idea's ?

The ZFS panic is from space_map.c in space_map_add(), happening via
zfs_panic_recover(). It in turn is affected by zfs_recover:

/*                                                                                                                                                                                                                                             * zfs_recover can be set to nonzero to attempt to recover from                                                                                                                                                                                * otherwise-fatal errors, typically caused by on-disk corruption.  When                                                                                                                                                                       * set, calls to zfs_panic_recover() will turn into warning messages.                                                                                                                                                                          */

Setting the vfs.zfs.recover loader variable to 1 might possibly
help. However I have never tried using that option and I'm not
familiar with the code, so I have no idea how safe it is. In
particular since you then seem to be getting a secondary panic (the
"buffer is not busy" which is from ffs_vfsops.

On another note:

http://www.google.com/search?client=opera&rls=en&q=zfs:+allocating+allocated+segment&sourceid=opera&ie=utf-8&oe=utf-8

indicates you're not the only person who has seen similar
errors. Unfortunately I cannot offer any insight other than to suggest
digging through the google results.

Was the original crash, prior to the mount problem, purely a software
crash or was there, for example, a power outtage? I'm wondering
whether there is any particular reason to believe there was some
hardware/firmware fault causing corruption.

-- 
/ Peter Schuller

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