I think you're looking for this. http://ceph.com/docs/master/man/8/rbd/#cmdoption-rbd--order
It's used when you create the RBD images. 1MB is order=20, 512 is order=19. Thanks, Bill Sanders On Thu, Aug 13, 2015 at 1:31 AM, Vickey Singh <vickey.singh22...@gmail.com> wrote: > Thanks Nick for your suggestion. > > Can you also tell how i can reduce RBD block size to 512K or 1M , do i > need to put something in clients ceph.conf ( what parameter i need to set ) > > Thanks once again > > - Vickey > > On Wed, Aug 12, 2015 at 4:49 PM, Nick Fisk <n...@fisk.me.uk> wrote: > >> > -----Original Message----- >> > From: ceph-users [mailto:ceph-users-boun...@lists.ceph.com] On Behalf >> Of >> > Dominik Zalewski >> > Sent: 12 August 2015 14:40 >> > To: ceph-us...@ceph.com >> > Subject: [ceph-users] Cache tier best practices >> > >> > Hi, >> > >> > I would like to hear from people who use cache tier in Ceph about best >> > practices and things I should avoid. >> > >> > I remember hearing that it wasn't that stable back then. Has it changed >> in >> > Hammer release? >> >> It's not so much the stability, but the performance. If your working set >> will sit mostly in the cache tier and won't tend to change then you might >> be alright. Otherwise you will find that performance is very poor. >> >> Only tip I can really give is that I have found dropping the RBD block >> size down to 512kb-1MB helps quite a bit as it makes the cache more >> effective and also minimises the amount of data transferred on each >> promotion/flush. >> >> > >> > Any tips and tricks are much appreciated! >> > >> > Thanks >> > >> > Dominik >> >> >> >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> > > > _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > >
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