Re: Ceph journal

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Nov 1, 2012 at 10:33 PM, Gandalf Corvotempesta
<gandalf.corvotempesta@xxxxxxxxx> wrote:
> 2012/11/1 Mark Nelson <mark.nelson@xxxxxxxxxxx>:
>> It will do that for a while, based on how you've tweaked the flush intervals
>> and various journal settings to determine how much data ceph will allow to
>> hang out in the journal while still accepting new requests.
>
> Ceph is not able to write to both journal and disks simultaneously?
> For example, by using SSD for operating system and journal, we will be
> able to have not least than 100GB of journal that is a large amount of
> data wrote at SSD speed.
>
> When ceph has to flush this data to disks, will stop to write more
> data to journal?

No, of course it will flush data to the disk at the same time as it
will take writes to the journal. However, if you have a 1GB journal
that writes at 200MB/s and a backing disk that writes at 100MB/s, and
you then push 200MB/s through long enough that the journal fills up,
then you will slow down to writing at 100MB/s because that's as fast
as Ceph can fill up the backing store, and the journal is no longer
buffering.
-Greg
--
To unsubscribe from this list: send the line "unsubscribe ceph-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [CEPH Users]     [Ceph Large]     [Information on CEPH]     [Linux BTRFS]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux