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Creating OSDs and Journals

OSDs store data, journals accelerate write performance as all writes flow to the journal and are complete from the client perspective once the journal write is complete. OSDs map one-to-one with a Storage Pool (XFS) and Journals map one-to-one with a partition of a Physical Disk device like a SSD or NVMe device. Each appliance will typically have between 3x to 25x OSDs (15x to 125x disks in RAID5 units). For each 8x OSDs a SSD is needed as they're sliced up to produce 8x journal devices.

In practice it's better to use hardware RAID to protect and accelerate the journal device. Using RAID1 with two SSDs will make it easy to maintain with no downtime for the node. Going further, using RAID5 will boost performance and provide fault tolerance for a relatively small increase in hardware cost for a large boost in write performance.

All of the process of creating the Storage Pools, OSDs, Journals, and association of OSDs to Journals across all nodes is handled through this single dialog. Simply select the HDDs and assign them to the OSDs section, then select your SSDs and assign them to be journals. QuantaStor does a coordinated task across the appliances to configure all the storage for the cluster in just a couple minutes even with hyper-scale configurations.