panic: ffs_valloc: dup alloc

Eric Anderson anderson at
Tue Mar 14 13:32:11 UTC 2006

Uwe Doering wrote:
> Eric Anderson wrote:
>> I get the above panic after nfs clients attach to this nfs server and 
>> being read/write ops on it after an unclean shutdown.  I've fsck'ed 
>> the fs, and it marks it as clean, but I get this every time.  It's an 
>> NFS share of a GEOM stripe (about 2TB).
>> mode = 0100600, inum = 58456203, fs = /mnt
>> panic: ffs_valloc: dup alloc
> Do you happen to have disk mirroring on this server (RAID 1)?  At 
> work, on a workstation with RAID 1, we once had a case where after a 
> power failure fsck would succeed, but subsequently, when mounting and 
> using the partitions, the kernel still paniced because of a corrupt 
> filesystem.  Repeatedly.
> This caused some major head scratching on our part until we figured 
> out what was happening.  The mirrored disks had gone out of sync.  For 
> performance reasons, a RAID 1 controller reads data from one disk 
> drive or the other, depending on which drive is less busy in that 
> particular moment.  So while fsck was able to find and fix some 
> filesystem inconsistencies there were still some more left in disk 
> sectors it didn't access.
> The RAID controller we used turned out to have a verification mode 
> where it would scan the disks and re-synchronize them.  Afterwards we 
> did another fsck run, and this fixed the remaining filesystem 
> inconsistencies.  The kernel panics were gone.
> Now, with the information you've provided I can't tell whether these 
> findings apply to your case, but perhaps this story helps at least 
> others in a similar situation.

I do have mirroring enabled on the OS drives, but this is happening with 
an external fiber channel array of SATA disks, striped using gstripe. 


Eric Anderson        Sr. Systems Administrator        Centaur Technology
Anything that works is better than anything that doesn't.

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