On Mon, Feb 17, 2014 at 12:29 AM, Alex Pearson <[email protected]> wrote: > Hi All, > I've been looking, but haven't been able to find any detailed documentation > about the journal usage on OSDs. Does anyone have any detailed docs they > could share? My initial questions are:
Hmm, I'm not sure if we have any serious laymen's stuff. Did you run a search through the docs at ceph.com/docs? > > Is the journal always write-only? (except under recovery) Yes. > I'm using BTRFS, in the default layout, which I'm thinking is very > inefficient as it basically forces the discs to seek all the time. (journal > partition at start of disc) > Is there a documented process to relocate the journal, without re-creating > the OSD? I believe that's in the docs. In short: flush the journal with the OSD cli flag, change the journal location in the config, create the journal with the OSD cli flag, turn on the OSD. > What have other people done to optimize the journal without purchasing SSD's? I'll let people who have done this talk about it in detail, but I think it tends to involve placing the journal on a partition at the outside edge of the disk and possibly giving the volume different properties in the RAID controller if you're using one. -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com > > > On another point, I'm running on HP Microservers (slow CPU - two cores) with > 5 discs - 1x OS, 4x OSD... I've currently got separate OSDs, however have > high load due to having more OSD's than cores in the box. I'm thinking of > JBOD'ing the OSD discs into pairs using LVM (different sized disks) so I have > only two OSD's, does anyone have any opinions on the merits of this? > > Also has anyone seen any CPU usage comparisons of XFS vs EXT4 vs BTRFS? > > Obviously I know I'm running an enterprise system on a shoe string, however > I'm keen to use this as a test bed to get comfortable with ceph before > recommending it in a real production environment, and I think optimizing and > understanding it here could have great benefits when I scale out. > > Lots of questsions, and as ever any insight would be appreciated on any of > the points! > > Regards > > Alex > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
