On Wed, 19 Aug 2015 10:02:25 +0100 Nick Fisk wrote: > > > > > > -----Original Message----- > > From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf > > Of Christian Balzer > > Sent: 19 August 2015 03:32 > > To: ceph-users@xxxxxxxxxxxxxx > > Cc: Nick Fisk <nick@xxxxxxxxxx> > > Subject: Re: any recommendation of using EnhanceIO? > > > > On Tue, 18 Aug 2015 20:48:26 +0100 Nick Fisk wrote: > > > > [mega snip] > > > 4. Disk based OSD with SSD Journal performance As I touched on above > > > earlier, I would expect a disk based OSD with SSD journal to have > > > similar performance to a pure SSD OSD when dealing with sequential > > > small IO's. Currently the levelDB sync and potentially other things > > > slow this down. > > > > > > > Has anybody tried symlinking the omap directory to a SSD and tested if > > hat makes a (significant) difference? > > I thought I remember reading somewhere that all these items need to > remain on the OSD itself so that when the OSD calls fsync it can be sure > they are all in sync at the same time. > Would be nice to have this confirmed by the devs. It being leveldb, you'd think it would be in sync by default. But even if it were potentially unsafe (not crash safe) in the current incarnation, the results of such a test might make any needed changes attractive. Unfortunately I don't have anything resembling a SSD in my test cluster. Christian -- Christian Balzer Network/Systems Engineer chibi@xxxxxxx Global OnLine Japan/Fusion Communications http://www.gol.com/ _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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