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FYI, if you supply a block device partition as journal, the param osd_journal_size is ignored, the entire partition is used by ceph. Thanks & Regards Somnath From: ceph-users [mailto:ceph-users-bounces@xxxxxxxxxxxxxx]
On Behalf Of Dominik Zalewski 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, From:
"Dominik Zalewski" <dzalewski@xxxxxxxxxxxxx> 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. Dominik On 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. Dominik On 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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