Hey Johansson,
thanks for the update here. two things in line with your response.
- for now, I am able to change these values via ceph.conf and restart the osd service, so are there any runtime commands as well to do so ? I am using Ceph Pacific or Octopus version installed using ceph-ansible.
- what do you mean by " allow more parallelism" - are you referring to modifying threads with this config "osd recovery threads" or please help elaborate.
Thanks once again for your help.
On Thu, Oct 28, 2021 at 1:05 PM Janne Johansson <icepic.dz@xxxxxxxxx> wrote:
--Den tors 28 okt. 2021 kl 09:09 skrev Lokendra Rathour <lokendrarathour@xxxxxxxxx>:Hi,we have been trying to test a scenario on ceph with the following configuration:cluster:
id: cc0ba1e4-68b9-4237-bc81-40b38455f713
health: HEALTH_OK
services:
mon: 3 daemons, quorum storagenode1,storagenode2,storagenode3 (age 4h)
mgr: storagenode2(active, since 22h), standbys: storagenode1, storagenode3
mds: cephfs:1 {0=storagenode1=up:active} 2 up:standby
osd: 3 osds: 3 up (since 4m), 3 in (since 4h)
rgw: 3 daemons active (storagenode1.rgw0, storagenode2.rgw0, storagenode3.rgw0)
task status:
scrub status:
mds.storagenode1: idle
data:
pools: 7 pools, 169 pgs
objects: 1.06M objects, 1.3 TiB
usage: 3.9 TiB used, 9.2 TiB / 13 TiB avail
pgs: 169 active+clean
io:
client: 43 KiB/s wr, 0 op/s rd, 3 op/s wr
recovery: 154 MiB/s, 98 objects/s
We have network links of 10GiG for all the networks used in Ceph. MTU is configured as 9000. But the Transfer rate as can be seen above is max 154 MiB/s which I feel is way low than possible.Test Case:We removed one node and added it back to the Ceph Cluster after reinstalling the OS. During this time of activity, Ceph has around 1.3 TB to rebalance in the newly added node. The time taken in such a case is approximate: 4 hours.Considering this as the production-grade setup with all production-grade infra, this time is too much.Query:
- Is there a way to optimize the recovery/rebalancing and i/o rate of Ceph?
- we found a few suggestions on the internet that we can modify the below parameters to achieve a good rate, but is this advisable
- osd max backfills, osd recovery max active, osd recovery max single start
- we have dedicated 10gig n/w infra so can we have any ideal value to reach max rate of recovery.
Any input would be helpful, we are really blocked here.If this is one spinning drive receiving data, then those figures look ok. If you instead had a large cluster with more drives, the sum of the recovery traffic would be more if you allow more parallelism. Looking at osd_max_backfills to see how many parallel backfills you will allow and looking at posts and guides like this:might also help.May the most significant bit of your life be positive.
skype: lokendrarathour
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