Yes, there should a separate partition per OSD. You are probably looking at 10-20GB journal partition per OSD. If you are creating your cluster using ceph-deploy it can create journal partitions for you.
"The expected throughput number should include the expected disk throughput (i.e., sustained data transfer rate), and network throughput. For example, a 7200 RPM disk will likely have approximately 100 MB/s. Taking the min() of the disk and network throughput should provide a reasonable expected throughput. Some users just start off with a 10GB journal size". For example:
On Wed, Aug 5, 2015 at 4:48 PM, Dominik Zalewski <dzalewski@xxxxxxxxxxxxx> wrote:
Yes, there should a separate partition per OSD. You are probably looking at 10-20GB journal partition per OSD. If you are creating your cluster using ceph-deploy it can create journal partitions for you."The expected throughput number should include the expected disk throughput (i.e., sustained data transfer rate), and network throughput. For example, a 7200 RPM disk will likely have approximately 100 MB/s. Taking the min() of the disk and network throughput should provide a reasonable expected throughput. Some users just start off with a 10GB journal size". For example:On Wed, Aug 5, 2015 at 4:38 PM, SUNDAY A. OLUTAYO <olutayo@xxxxxxxxxx> wrote:I intend to have 5-8 OSDs for 400GB SSD.Should there be different partitions for each OSD on the SSD?Thanks,
Sunday OlutayoFrom: "Dominik Zalewski" <dzalewski@xxxxxxxxxxxxx>
To: "SUNDAY A. OLUTAYO" <olutayo@xxxxxxxxxx>, "ceph-users" <ceph-users@xxxxxxxxxxxxxx>
Sent: Wednesday, August 5, 2015 3:38:20 PM
Subject: Re: Ceph DesignI would suggest splitting OSDs across two or more SSD journals (depending on OSD write speed and SSD sustained speed limits)e.g 2x Intel S3700 400GB for 8-10 OSDs or 4x Intel S3500 300GB for 8-10 OSDs (it may vary depending on the setup)If you RAID-1 SSD journals they will potentially "wear out" in the same time due to writes happening on both of them.You only going to get journal write performance penalty with RAID-1.DominikOn Wed, Aug 5, 2015 at 3:37 PM, Dominik Zalewski <dzalewski@xxxxxxxxxxxxx> wrote:I would suggest splitting OSDs across two or more SSD journals (depending on OSD write speed and SSD sustained speed limits)e.g 2x Intel S3700 400GB for 8-10 OSDs or 4x Intel S3500 300GB for 8-10 OSDs (it may vary depending on the setup)If you RAID-1 SSD journals they will potentially "wear out" in the same time due to writes happening on both of them.You only going to get journal write performance penalty with RAID-1.DominikOn Tue, Aug 4, 2015 at 10:54 PM, SUNDAY A. OLUTAYO <olutayo@xxxxxxxxxx> wrote:I am thinking of having ceph journal on a RAID1 SSD.Kindly advise me on this, does the RAID1 SSD for journal make sense?
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