slowdown of zfs (tx->tx)

[Ronald Klop]

On Thu, 17 Jan 2013 10:32:59 +0100, Nicolas Rachinsky  
<fbsd-mas-0 at ml.turing-complete.org> wrote:

> * Andriy Gapon <avg at FreeBSD.org> [2013-01-16 14:05 +0200]:
>> on 16/01/2013 12:14 Steven Hartland said the following:
>> > You only have ~11% free so yer it is pretty full ;-)
>>
>> just in case, Steve is not kidding.
>>
>> Those free hundreds of gigabytes could be spread over the terabytes and  
>> could be
>> quite fragmented if the pool has a history of adding and removing lots  
>> of files.
>>  ZFS could be spending quite a lot of time in that case when it looks  
>> for some
>> free space and tries to minimize further fragmentation.
>>
>> Empirical/anecdotal safe limit on pool utilization is said to be about  
>> 70-80%.
>>
>> You can test if this guess is true by doing the following:
>> kgdb -w
>> (kgdb) set metaslab_min_alloc_size=4096
>>
>> If performance noticeably improves after that, then this is your  
>> problem indeed.
>
> I tried this, but I didn't notice any difference in performance.
>
> Next I'll try the update Artem suggested.
>
> Thanks
>
> Nicolas

Did you already try to free some space?

Ronald.