Hi Jeldrik, You are right. In this situation, you are better off collocating the journal on the new SSD OSDs and recycling your journal to an OSD (if its wear level allows it) once all its attached HDD OSDs are replaced. As a side note, make sure to monitor the write endurance/wear level on the SSDs.
Cheers, Maxime Guyot <mailto:[email protected]> On 20/12/16 15:59, "ceph-users on behalf of Jeldrik" <[email protected] on behalf of [email protected]> wrote: Hi all, i know this topic has been discussed a few times from different perspectives here, but I could not really get to the answer I need. We're running a ceph cluster with the following setup: 3 Nodes with 6 OSDs (HDD) and 2 Journal Disks (SSD) each. This is a more or less small setup for a private cluster environment. We now want to replace the HDDs with SSDs because the customer needs more performance. We use INTEL DC SSDs as journal devices and we want to use the same model as OSDs. Because of hardware limitations we are not able to upgrade the journal devices to let's say PCIe NVMe. We could easily just go an replace the HDDs one by one. But the question is: wouldn't the journal be the new bottleneck? The OSDs are the same SSD model so they would have the same read/write performance as the journal and every OSD could just get to about 1/3 of there performance capabilities, am I right? Wouldn't it be better to place the journal of each OSD on the very same SSD and use the old journals as additional OSDs? We would get 6 OSDs more and they would only drop to 1/2 of there performance capabilities. At least this is what I think :-) So, am I right here that it would be better to place journal and OSD on the same SSD in this setup? Thanks and regards, Jeldrik _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
