Re: All-Flash Ceph cluster and journal

[Mike Almateia <mike.almateia@gmail.com>]

19-Nov-15 17:34, Mark Nelson пишет:
> This is actually the direction newstore is heading with the
> newstore_min_alloc_size so that you can configure when to write into the
> rocksdb WAL.  By default it's set to 512k, but for SSDs we will almost
> certainly want to go smaller.
>
> On 11/19/2015 05:29 AM, Mike Almateia wrote:
>> Hello.
>>
>> By now we have SSD disks with a great perfomance under O_DIRECT/O_SYNC
>> flags (and we recomended to use they for journal).
>>
>> Why in a All-Flash type Ceph clusters we still use journal and them put
>> a data into OSD?
>> Why we can't just write a data into OSD with O_DIRECT/O_SYNC flags,
>> without journal?
>>
>> Can we just switch off the journal functional for all-flash ceph
>> clusters?
>>

Thanks for answer!

By now is it resonable to use NVMe Flash for OSD on Ceph? Overpower? Is 
it possible to achive full speed NVMe Flash driver under Ceph?
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