Cannot rm files when ZFS is full

[Mark Stapper]

Christian Walther wrote:
> 2009/7/29 grarpamp <grarpamp at gmail.com>:
>   
>> One week old build...
>>
>> # df -i .
>> Filesystem   1K-blocks      Used Avail Capacity iused ifree %iused  Mounted on
>> ram01/mnt1 239465344 239465344     0   100%   13163     0  100%   /mnt1
>> # ls -aliT zero
>> 20797 -rw-r--r--  1 user user  43515904 Jul 28 23:20:57 2009 zero
>> # rm -f zero
>> rm: zero: No space left on device
>> # :> zero
>> cannot create zero: File exists
>> # cp /dev/null zero
>> overwrite zero? (y/n [n]) y
>> # ls -aliT zero
>> 20797 -rw-rw-rw-  1 root  wheel  0 Jul 28 23:25:17 2009 zero
>> # rm -f zero
>> [gone]
>>     
>
>
> this is a known problem with the current version of ZFS. Due to the
> way ZFS handles access to the data it stores, even a rm causes a
> write, which requires some additional disk space in the beginning:
> Instead of simply unlinking what should be removed ZFS creates another
> tree without the removed data. Only if this new tree has been entirely
> written to disk the old information is removed. This is a rather rough
> explanation and probably not entirely correct, but I hope it suffices.
> Only hope: Make sure that not all disk space is used.
>
> Christian
>   
Indeed, if by some coincident (like a growing logfile) every single byte
is used, even the copy action might fail...
To prevent this you could set the maximum size of all partitions in your
pool so that the sum of them is smaller then the size of your pool.
Just a thought.
Greetz,
Mark

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