Re: ceph Performance random write is more then sequential

[Sumit Gaur <sumitkgaur@xxxxxxxxx>]

Hi All,

What I saw after enabling RBD cache it is working as expected, means sequential write has better MBps than random write. can somebody explain this behaviour ? Is RBD cache setting must for ceph cluster to behave normally ?

Thanks

sumit

On Mon, Feb 2, 2015 at 9:59 AM, Sumit Gaur <sumitkgaur@xxxxxxxxx> wrote:

Hi Florent,

Cache tiering , No . 

** Our Architecture :

vdbench/FIO inside VM <--> RBD without cache <-> Ceph Cluster (6 OSDs + 3 Mons) 

Thanks

sumit

[root@ceph-mon01 ~]# ceph -s

    cluster 47b3b559-f93c-4259-a6fb-97b00d87c55a

     health HEALTH_WARN clock skew detected on mon.ceph-mon02, mon.ceph-mon03

     monmap e1: 3 mons at {ceph-mon01=192.168.10.19:6789/0,ceph-mon02=192.168.10.20:6789/0,ceph-mon03=192.168.10.21:6789/0}, election epoch 14, quorum 0,1,2 ceph-mon01,ceph-mon02,ceph-mon03

     osdmap e603: 36 osds: 36 up, 36 in

      pgmap v40812: 5120 pgs, 2 pools, 179 GB data, 569 kobjects

            522 GB used, 9349 GB / 9872 GB avail

                5120 active+clean

On Mon, Feb 2, 2015 at 12:21 AM, Florent MONTHEL <fmonthel@xxxxxxxxxxxxx> wrote:

Hi Sumit

Do you have cache pool tiering activated ?
Some feed-back regarding your architecture ?
Thanks

Sent from my iPad

> On 1 févr. 2015, at 15:50, Sumit Gaur <sumitkgaur@xxxxxxxxx> wrote:
>
> Hi
> I have installed 6 node ceph cluster and to my surprise when I ran rados bench I saw that random write has more performance number then sequential write. This is opposite to normal disk write. Can some body let me know if I am missing any ceph Architecture point here ?
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> ceph-users mailing list
> ceph-users@xxxxxxxxxxxxxx
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com

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