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Hi Lin,
Yes it will read from the primary osd, but for the reasons stated this should not impact performance.
Maged
On 2018-01-26 19:52, shadow_lin wrote:
Hi Maged,
I just want to make sure if I understand how ceph client read from cluster.So with current version of ceph(12.2.2) the client only read from the primary osd(one copy),is that true?
发件人：Maged Mokhtar <mmokhtar@xxxxxxxxxxx>
发送时间：2018-01-26 20:27
主题：Re: How ceph client read data from ceph cluster
收件人："shadow_lin"<shadow_lin@xxxxxxx>
抄送："ceph-users"<ceph-users@xxxxxxxxxxxxxx>
On 2018-01-26 09:09, shadow_lin wrote:
Hi List,
I read a old article about how ceph client read from ceph cluster.It said the client only read from the primary osd. Since ceph cluster in replicate mode have serveral copys of data only read from one copy seems waste the performance of concurrent read from all the copys.
But that artcile is rather old so maybe ceph has imporved to read from all the copys? But I haven't find any info about that.
Any info about that would be appreciated.
Thanks
Hi
The majority of cases you will have more concurrent io requests than disks, so the load will already be distributed evenly. If this is not the case and you have a large cluster with fewer clients, you may consider using object/rbd striping so each io will be divided into different osd requests.
Maged
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