On Mon, Jan 14, 2013 at 6:09 AM, Florian Haas <florian@xxxxxxxxxxx> wrote: > Hi Mark, > > thanks for the comments. > > On Mon, Jan 14, 2013 at 2:46 PM, Mark Nelson <mark.nelson@xxxxxxxxxxx> wrote: >> Hi Florian, >> >> Couple of comments: >> >> "OSDs use a write-ahead mode for local operations: a write hits the journal >> first, and from there is then being copied into the backing filestore." >> >> It's probably important to mention that this is true by default only for >> non-btrfs file systems. See: >> >> http://ceph.com/wiki/OSD_journal > > I am well aware of that, but I've yet to find a customer (or user) > that's actually willing to entrust a production cluster with several > hundred terabytes of data to btrfs. :) Besides, the whole post is > about whether or not to use dedicated SSD block devices for OSD > journals, and if you're tossing everything into btrfs you've already > made the decision to use in-filestore journals. That is absolutely not the case. btrfs works just fine with an external journal on SSD or whatever else; what made you think otherwise? -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
