That looks right to me... PRs for the Ceph docs are welcome! :) On Mon, Oct 16, 2017 at 4:35 PM Alexander Kushnirenko <kushnire...@gmail.com> wrote:
> Hi, Gregory, Ian! > > There is very little information on striper mode in Ceph documentation. > Could this explanation help? > > The logic of striper mode is very much the same as in RAID-0. There are 3 > parameters that drives it: > > stripe_unit - the stripe size (default=4M) > stripe_count - how many objects to write in parallel (default=1) > object_size - when to stop increasing object size and create new objects. > (default =4M) > > For example if you write 132M of data (132 consecutive pieces of data 1M > each) in striped mode with the following parameters: > stripe_unit = 8M > stripe_count = 4 > object_size = 24M > Then 8 objects will be created - 4 objects with 24M size and 4 objects > with 8M size. > > Obj1=24M Obj2=24M Obj3=24M Obj4=24M > 00 .. 07 08 .. 0f 10 .. 17 18 .. 1f <-- > consecutive 1M pieces of data > 20 .. 27 21 .. 2f 30 .. 37 38 .. 3f > 40 .. 47 48 .. 4f 50 .. 57 58 .. 5f > > Obj5= 8M Obj6= 8M Obj7= 8M Obj8= 8M > 60 .. 67 68 .. 6f 70 .. 77 78 .. 7f > > Alexander. > > > > > On Wed, Oct 11, 2017 at 3:19 PM, Alexander Kushnirenko < > kushnire...@gmail.com> wrote: > >> Oh! I put a wrong link, sorry The picture which explains stripe_unit >> and stripe count is here: >> >> >> https://indico.cern.ch/event/330212/contributions/1718786/attachments/642384/883834/CephPluginForXroot.pdf >> >> I tried to attach it in the mail, but it was blocked. >> >> >> On Wed, Oct 11, 2017 at 3:16 PM, Alexander Kushnirenko < >> kushnire...@gmail.com> wrote: >> >>> Hi, Ian! >>> >>> Thank you for your reference! >>> >>> Could you comment on the following rule: >>> object_size = stripe_unit * stripe_count >>> Or it is not necessarily so? >>> >>> I refer to page 8 in this report: >>> >>> >>> https://indico.cern.ch/event/531810/contributions/2298934/attachments/1358128/2053937/Ceph-Experience-at-RAL-final.pdf >>> >>> >>> Alexander. >>> >>> On Wed, Oct 11, 2017 at 1:11 PM, <ian.john...@stfc.ac.uk> wrote: >>> >>>> Hi Gregory >>>> >>>> You’re right, when setting the object layout in libradosstriper, one >>>> should set all three parameters (the number of stripes, the size of the >>>> stripe unit, and the size of the striped object). The Ceph plugin for >>>> GridFTP has an example of this at >>>> https://github.com/stfc/gridFTPCephPlugin/blob/master/ceph_posix.cpp#L371 >>>> >>>> >>>> >>>> At RAL, we use the following values: >>>> >>>> >>>> >>>> $STRIPER_NUM_STRIPES 1 >>>> >>>> $STRIPER_STRIPE_UNIT 8388608 >>>> >>>> $STRIPER_OBJECT_SIZE 67108864 >>>> >>>> >>>> >>>> Regards, >>>> >>>> >>>> >>>> Ian Johnson MBCS >>>> >>>> Data Services Group >>>> >>>> Scientific Computing Department >>>> >>>> Rutherford Appleton Laboratory >>>> >>>> >>>> >>>> _______________________________________________ >>>> ceph-users mailing list >>>> ceph-users@lists.ceph.com >>>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>>> >>>> >>> >> >
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