Hi,
On 09/20/2017 12:24 PM, Sean Purdy wrote:
On Wed, 20 Sep 2017, Burkhard Linke said:
The main reason for having a journal with filestore is having a block device
that supports synchronous writes. Writing to a filesystem in a synchronous
way (e.g. including all metadata writes) results in a huge performance
penalty.
With bluestore the data is also stored on a block devices, and thus also
allows to perform synchronous writes directly (given the backing storage is
handling sync writes correctly and in a consistent way, e.g. no drive
caches, bbu for raid controllers/hbas). And similar to the filestore journal
Our Bluestore disks are hosted on RAID controllers. Should I set cache policy as WriteThrough for these disks then?
It depends on the setup and availability of a BBU. If you have a BBU and
cache on the controller, using write back should be ok if you monitor
the BBU state. To be on the safe side is using write through and live
with the performance impact.
There's also another thread on the mailing list discussing the choice of
controllers/hba. Maybe there's more information available in that
thread, especially with regard to vendors, firmware etc.
Regards,
Burkhard
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
