Unable to recover hammer volume.

Tomohiro Kusumi kusumi.tomohiro at gmail.com
Mon Jan 16 06:15:50 PST 2017

hammer_btree_extract: CRC DATA @ 9000000a4a1f3280/128 FAILED
hammer_btree_extract: CRC DATA @ 9000000a4a1f3280/128 FAILED
hammer_btree_extract: CRC DATA @ 9000000a4a1f3000/128 FAILED
hammer_btree_extract: CRC DATA @ 9000000a4a1f3000/128 FAILED
hammer_btree_extract: CRC DATA @ 9000000a4a1f3080/128 FAILED

This means bunch of inodes in certain sectors nearby were somehow
corrupted. These are often found only when those inodes are read the
next time after corruption, thus doesn't necessary affect booting
unless those inodes are read on booting.

Onboot recovery really has nothing to do with random broken sectors
where undo fifo is not involved, nor is it a problem of filesystems in
general including hammer1. Also note that "recovery" here doesn't mean
hammer1 somehow magically fixes user data. It means the filesystem
keeps consistency of itself.

Having said that, hammer1 could give an option for users to at least
do whatever they want to do on a broken fs. It currently forces
readonly mount, kernel panic, etc.

2017-01-16 22:52 GMT+09:00 PeerCorps Trust Fund <ipc at peercorpstrust.org>:
> Hi,
> It sounds pretty much like its supposed to operate if your file system tree
> is potentially corrupted somehow. You may very well need to copy off the
> data and recreate the file system. Unless of course the underlying block
> storage has some issues (bad sectors etc.).
> I do recall there not yet being a way to gracefully fix a "broken" HAMMER
> file system.
> Perhaps I am wrong and someone else will offer more enlightened feedback.
> Out of curiosity when the file system was mounted at boot, did it not fail
> to mount? It seems like it should have been brought back to a consistent
> state after your reboot.
> Mike
> On 01/16/2017 03:32 PM, jscottkasten at yahoo.com wrote:
>> Hi guys,
>> I've tried searching the answer for this, but cannot find any proper
>> discussion on the topic.
>> I have a hammer volume that had to be forced into an unclean shutdown.
>> There are some files and/or folders that now have CRC errors.  When the
>> damaged data is encountered, it causes hammer to report a critical error and
>> remount the file system as READ ONLY.  Thus, I am unable to delete or remove
>> the bad data in any way to recover the file system to an operable state.
>> Is there some tool that I should run on the file system to do this???  I
>> know the bad data is restricted to a small number of folders.  Would love to
>> somehow purge it so the volume can be returned to normal operation.  It's a
>> 2TB volume, so I'm hoping I don't have to reformat and re-create the volume.
>> Thanks for any advice.
>> Regards,
>> -J. Scott Kasten-

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