deleting files when no disk space is available

[Michael Neumann]

On 04/09/16 19:08, Christoph Harder wrote:
> Or maybe not.
>
> It tried to run the application with changed parameters again.
> It failed with a hammer error message (...panic...) and a debugger.
>
> I did enter "reset", since I didn't find a quit/exit command.
>
> After restart I do get error messages like:
>
> no B_DEVMAGIC (bootdev=0)
> Mounting root from hammer:serno/F34924R03250.s1d
> HAMMER(ROOT) Illegal UNDO TAIL signature at 300000001e636e30
> HAMMER(ROOT) recovery failure during seqno backscan
> HAMMER(ROOT) recovery complete
> Failed to recover HAMMER filesystem on mount
> Root mount failed: 5
>
> Manual root filesystem specification:
> ....
>
>
> So is there a way to recover this somehow or is it easier to just do a
> fresh install?


I haven't seen this particular error myself. Several years ago I had an 
issue with a too small UNDO log, but this was fixed.

You can always mount a HAMMER filesystem as read-only. In this case,
I guess, it should not trigger the UNDO TAIL signature panic. Once you 
have the filesystem readonly, you can back it up, and later restore it
to a new HAMMER filesystem.

Regards,

   Michael

>
> Best regards,
> Christoph
>
>
> Am 09.04.2016 um 18:47 schrieb Christoph Harder:
>> Hello,
>>
>> yes, that did the job. Thank you.
>>
>> Best regards,
>> Christoph
>>
>> Am 09.04.2016 um 18:14 schrieb Michael Neumann:
>>>
>>>
>>> On 04/09/16 18:08, Tomohiro Kusumi wrote:
>>>> If you're using hammer, rm file isn't deleting anything from your
>>>> filesystem capacity.
>>>>
>>>> But aside from the fact rm isn't deleting anything, I think there is a
>>>> bug in ENOSPC handling.
>>>> I've once saw kernel panic soon after hitting ENOSPC.
>>>>
>>>>
>>>> 2016-04-09 22:16 GMT+09:00 Christoph Harder <shadowomf at arcor.de>:
>>>>> Hello,
>>>>>
>>>>> I do have a small problem, I've written a program that filled all
>>>>> available
>>>>> disk space (I know not very smart...).
>>>>> Well now I have a few SQLite database files that I can't get rid of.
>>>>>
>>>>> When executing "rm *" or just calling "rm a.9.db" for a single file
>>>>> I do get
>>>>> the error message "rm: a.9.db: No space left on device".
>>>>> I suspect there is some space required to undo the delete which might
>>>>> require extra space.
>>>
>>> "hammer cleanup" or hammer prune[-everything] will help.
>>>
>>> Regards,
>>>
>>>    Michael
>>>
>>