> 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 ?? Also does straw2 support comes comes within Kernel OR by installing Ceph Hammer / Later binaries ? Does Centos 7.1 ( 3.10 ) supports straw2 ? > > -- > David Clarke > Systems Architect > Catalyst IT > > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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