Prognosis for damaged HAMMER file system?

Matthew Dillon dillon at
Sat Jan 31 10:36:34 PST 2015

It's safest to copy the data off and recreate the filesystem.  The domain
error in mirror-read reflects the CRC failure that checkmap found.  The
mirroring code is exiting on that error so you probably don't have a
complete mirror copy.  I would mount the filesystem and use cpdup to make
the copy and see what errors (if any) cpdup reports.


On Sat, Jan 31, 2015 at 3:57 AM, Vasily Postnicov <shamaz.mazum at>

> Hello.
> I have a possibly damaged HAMMER fs. Look at output of hammer checkmap
> command:
> ressurected# hammer -f
> /dev/serno/5VPD5Y9X.s1:/dev/serno/6PT5CW16.s1:/dev/serno/WD-WMASY1750086.s1d
> checkmap
> Volume header   records=0 next_tid=0000000279fe6800
>                 bufoffset=0000000044040000
> Collecting allocation info from B-Tree: B    NODE 80000005221c3000 cnt=32
> p=c000000522191000 type=L depth=4 mirror 0000000278289c40 {
> done
> I think this was caused by damaged hardware (overheated CPU).
> I do not see any lost/inconsistent data yet, only hammer mirror-read
> command fails with one of PFSes:
> ressurected# hammer mirror-read /home/shared > /dev/zero
> Prescan to break up bulk transfer
> Mirror-read /home/shared failed: Numerical argument out of domain
> Can I lose data if I continue to use this fs? May it be cured (e.g. by
> copying data from /home/shared to newly created PFS and then destroying the
> old one)?
>                   With best regards, Vasily.
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