gjournal performance issues
Fluffles
etc at fluffles.net
Tue Jun 26 14:54:13 UTC 2007
Ivan Voras wrote:
> Fluffles wrote:
>
>> First, my setup:
>> 8 disks in RAID5 using geom_raid5, gjournal on top where both the
>> journal (1GB) and the data is stored on the same consumer. Since
>> gjournal uses both metadata and file/dir for journaling, this means
>> that, theoretically, the write speed of sequential operations is
>> doubled. Unfortunately, it appears to have crashed.
>
> Just to rule out geom_raid5, can you repeat your tests with geom_raid3?
Sounds logical. But: RAID3 does not have any 2-phase writes, all writes
are 1-phase, involving all disks. Thus RAID3 would be less affected by
non-contigious writes. I will test with debuglevel or with geom_nop to
see the I/O that geom_journal produces, and to see if this I/O is
contigious or not. I hope to know more in a day or so.
Thanks for your input Ivan and Pawel! More testing is needed...
- Veronica
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