[Ceph-community] [ceph-users] rbd format v2 support

David Z david.z1003 at yahoo.com
Mon Jun 8 19:52:35 PDT 2015


Hi Ilya,
Thanks for the reply. I knew that v2 image can be mapped if using default striping parameters without --stripe-unit or --stripe-count.

It is just the rbd performance (IOPS & bandwidth) we tested hasn't met our goal. We found at this point OSDs seemed not to be the bottleneck, so we want to try "fancy striping".
Do you know if there is an approximate ETA for this feature? Or it would be great that you could share some info on tuning rbd performance. Anything will be appreciated.
Thanks.
Zhi (David) 

     On Sunday, June 7, 2015 3:50 PM, Ilya Dryomov <idryomov at gmail.com> wrote:
   

 On Fri, Jun 5, 2015 at 6:47 AM, David Z <david.z1003 at yahoo.com> wrote:
> Hi Ceph folks,
>
> We want to use rbd format v2, but find it is not supported on kernel 3.10.0 of centos 7:
>
> [ceph at xxxx ~]$ sudo rbd map zhi_rbd_test_1
> rbd: sysfs write failed
> rbd: map failed: (22) Invalid argument
> [ceph at xxxx ~]$ dmesg | tail
> [662453.664746] rbd: image zhi_rbd_test_1: unsupported stripe unit (got 8192 want 4194304)
>
> As it described in ceph doc, it should be available from kernel 3.11. But I checked the code of kernel 3.12, 3.14 and even 4.1. This piece of code is still there, see below links. Do I miss some codes or info?

What you are referring to is called "fancy striping" and it is
unsupported (work is underway but it's been slow going).  However
because v2 images with *default* striping parameters disk format wise
are the same as v1 images, you can map a v2 image provided you didn't
specify custom --stripe-unit or --stripe-count on rbd create.

Thanks,

                Ilya


  
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