On 11/13/2015 09:11 AM, Karan Singh wrote: > > >> On 11 Nov 2015, at 22:49, David Clarke <davidc@xxxxxxxxxxxxxxx> wrote: >> >> On 12/11/15 09:37, Gregory Farnum wrote: >>> On Wednesday, November 11, 2015, Wido den Hollander <wido@xxxxxxxx >>> <mailto:wido@xxxxxxxx>> wrote: >>> >>> On 11/10/2015 09:49 PM, Vickey Singh wrote: >>>> On Mon, Nov 9, 2015 at 8:16 PM, Wido den Hollander <wido@xxxxxxxx >>> <javascript:;>> wrote: >>>> >>>>> On 11/09/2015 05:27 PM, Vickey Singh wrote: >>>>>> Hello Ceph Geeks >>>>>> >>>>>> Need your comments with my understanding on straw2. >>>>>> >>>>>> - Is Straw2 better than straw ? >>>>> >>>>> It is not persé better then straw(1). >>>>> >>>>> straw2 distributes data better when not all OSDs are equally >>>>> sized/weighted. >>>>> >>>>>> - Is it straw2 recommended for production usage ? >>>>>> >>>>> >>>>> I'm using it in multiple clusters and it works fine. >>>>> >>>> >>>> Yes i followed your update on twitter :) >>>> >>>> >>>>> >>>>>> I have a production Ceph Firefly cluster , that i am going to >>> upgrade to >>>>>> Ceph hammer pretty soon. Should i use straw2 for all my ceph pools ? >>>>>> >>>>> >>>>> I would upgrade to Hammer first and make sure that ALL clients >>> are updated. >>>>> >>>>> In case you are using KVM/Qemu, you will have to stop those processes >>>>> first and start them again before they are using the new code. >>>>> >>>> >>>> Thanks a lot for this pointer, i didn't knew this. So restarting >>> KVM / QEMU >>>> process effect running VMs ? ( some downtime ) >>>> >>> >>> Yes. You can also (live) migrate to another host since that will spawn >>> Qemu with fresh code on the other host. >>> >>> But you have to make sure all running/connected clients support straw2 >>> before you enable straw2. >>> >>> >>> I believe straw2 only requires monitor support -- unlike the tuna led >>> involved in executing CRUSH, straw2 is just about how the OSD/bucket >>> weights get converted into a sort of "internal" straw weight. That's >>> done on the monitors and encoded into the maps. >>> >>> Right? >>> -Greg >> >> I don't believe that's the case. If you convert a CRUSH map to use >> straw2 then any connected QEMU/librbd clients without straw2 support >> will die with something like: >> >> terminate called after throwing an instance of >> 'ceph::buffer::malformed_input' >> what(): buffer::malformed_input: unsupported bucket algorithm: 5 >> >> Where: >> >> ceph/src/crush/crush.h:CRUSH_BUCKET_STRAW2 = 5, >> > > Thanks David / Wido for pointing this out. > > So does it means , before changing crush with Straw2 , one should make sure their clients ( openstack or anything else ) supports straw2 ?? Indeed. Make sure that all clients (including the running ones!!) support straw2. As mentioned, restart Qemu or live migrate to another host. A reboot inside the instance is NOT sufficient, librados has to be re-initialized and this can only be done by stopping and starting Qemu. > Also does straw2 support comes comes within Kernel OR by installing Ceph Hammer / Later binaries ? Newer kernels support straw2, but I think you need at least kernel 4.1 > Does Centos 7.1 ( 3.10 ) supports straw2 ? I don't think so. Wido > > > >> >> -- >> David Clarke >> Systems Architect >> Catalyst IT >> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@xxxxxxxxxxxxxx >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > -- Wido den Hollander 42on B.V. Ceph trainer and consultant Phone: +31 (0)20 700 9902 Skype: contact42on _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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