Re: Where to put the journal

["Xuân Baldauf" <xuan--2004.08.01--reiserfs-list--namesys.com@baldauf.org>]

Edward Shishkin wrote:

> Vladimir V. Saveliev wrote:
>
>> Hello
>>
>> Xuân Baldauf wrote:
>>
>>> Hello,
>>>
>>> I want to setup a Linux software RAID 5 over disks of different 
>>> speed with reiserfs on top. I know that the journal has to be 
>>> accessed frequently for comparably small accesses. That's why I'm 
>>> considering to "offload" the journal onto an extra partition on a 
>>> faster disk of the RAID set.
>>>
>>> Thus, the journal would not be protected by the RAID, but this is 
>>> not so important for me.
>>>
>>> Is this kind of reasoning sane? Would there be any speedup by 
>>> offloading the journal?
>>>
>>
>
> Hello.
> Unfortunately comprehensive results of journal relocation are obsolete
> as it was done at the beginning of mongo evolution. As I remember there
> were no any essential speedups. The only result of  journal  
> relocation that
> was created by new mongo benchmark can be found here:
> http://thebsh.namesys.com/benchmarks/journal_relocation_to_NVRAM.html

Thank you,

essentially, these numbers say that relocation provided a speedup of 
about 10% for write. This surprises me a bit, because I expected a 
significantly smaller seek count for a write operation. Nevertheless, 
maybe I should run benchmarks with many small files for myself. :-)

>
> Edward.


ciao,

Xuân Baldauf.

>
>> Person who did some tests on non standard journal is on vacation. He 
>> is expected to come back today. Maybe he remembers benchmark results,
>