Chapter 38. Removing a Cache Tier
Removing a cache tier differs depending on whether it is a writeback cache or a read-only cache.
38.1. Removing a Read-Only Cache
Since a read-only cache does not have modified data, you can disable and remove it without losing any recent changes to objects in the cache.
Change the cache-mode to
noneto disable it. :ceph osd tier cache-mode {cachepool} noneFor example:
ceph osd tier cache-mode hot-storage none
Remove the cache pool from the backing pool. :
ceph osd tier remove {storagepool} {cachepool}For example:
ceph osd tier remove cold-storage hot-storage
38.2. Removing a Writeback Cache
Since a writeback cache may have modified data, you must take steps to ensure that you do not lose any recent changes to objects in the cache before you disable and remove it.
Change the cache mode to
forwardso that new and modified objects will flush to the backing storage pool. :ceph osd tier cache-mode {cachepool} forwardFor example:
ceph osd tier cache-mode hot-storage forward
Ensure that the cache pool has been flushed. This may take a few minutes:
rados -p {cachepool} lsIf the cache pool still has objects, you can flush them manually. For example:
rados -p {cachepool} cache-flush-evict-allRemove the overlay so that clients will not direct traffic to the cache. :
ceph osd tier remove-overlay {storagetier}For example:
ceph osd tier remove-overlay cold-storage
Finally, remove the cache tier pool from the backing storage pool. :
ceph osd tier remove {storagepool} {cachepool}For example:
ceph osd tier remove cold-storage hot-storage
