2.6. Understanding Storage Tiers¶
Storage tiers represent a way to organize storage space. You can use them to keep different categories of data on different chunk servers. For example, you can use high-speed solid-state drives to store performance-critical data instead of caching cluster operations.
When assigning disks to tiers, have in mind that faster storage drives should be assigned to higher tiers. For example, you can use tier 0 for backups and other cold data (CS without SSD cache), tier 1 for virtual environments–a lot of cold data but fast random writes (CS with SSD cache), tier 2 for hot data (CS on SSD), caches, specific disks, and such.
This recommendation is related to how Acronis Storage works with storage space. If a storage tier runs out of free space, Acronis Storage will attempt to temporarily use a lower tier. If you add more storage to the original tier later, the data, temporarily stored elsewhere, will be moved to the tier where it should have been stored originally.
For example, if you try to write data to the tier 2 and it is full, Acronis Storage will attempt to write that data to tier 1, then to tier 0. If you add more storage to tier 2 later, the aforementioned data, now stored on the tier 1 or 0, will be moved back to the tier 2 where it was meant to be stored originally.