Hi, I have a couple of HW provisioning questions in regards to SSD for OSD Journals.
I'd like to provision 12 OSDs per a node and there are enough CPU clocks and Memory. Each OSD is allocated one 3TB HDD for OSD data - these 12 * 3TB HDDs are in non-RAID. For increasing access and (sequential) write performance, I'd like to put 2 SSDs for OSD journals - these two SSDs are not mirrored. By the rule of thumb, I'd like to mount the OSD journals (the path below) to the "SSD partitions" accordingly. /var/lib/ceph/osd/$cluster-$id/journal Question 1. Which way is recommended between: (1) Partitions for OS/Boot and 6 OSD journals on #1 SSD, and partitions for the rest 6 OSD journals on #2 SSD; (2) OS/Boot partition on #1 SSD, and separately 12 OSD journals on #2 SSD? BTW, for better utilization of expensive SSDs, I prefer the first way. Should it be okay? Question 2. I have several capacity options for SSDs. What's the capacity requirement if there are 6 partitions for 6 OSD journals on a SSD? If it's hard to generalize, please provide me with some guidelines. Thanks, Peter
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