A cache tier has several configuration options that define the cache tier policy. This cache tier policy is required to flush data from the cache tier to the storage tier in case of a writeback. In the case of the read-only cache tier, it moves the data from the storage tier to the cache tier. In this recipe, I have tried to demonstrate the cache tier with the writeback mode. These are some settings that you should configure for your production environment, with different values based on your requirements:
- For production deployment, you should use the 'bloom filters' data structure:
# ceph osd pool set cache-pool hit_set_type bloom hit_set_countdefines how much time in seconds each hit set should cover, andhit_set_perioddefines how many such hit sets are to be persisted:# ceph osd pool set cache-pool hit_set_count 1 # ceph osd pool set cache-pool hit_set_period 300
target_max_bytesis the maximum number of bytes after the cache-tiering agent starts flushing/evicting objects from a cache pool. Whereastarget_max_objectsis the maximum number of objects after which a cache-tiering agent starts flushing/evicting objects from a cache pool:# ceph osd pool set cache-pool target_max_bytes 1000000 # ceph osd pool set cache-pool target_max_objects 10000
- Enable
cache_min_flush_ageandcache_min_evict_age, which are the times in seconds that a cache-tiering agent takes to flush and evict objects from a cache tier to a storage tier:# ceph osd pool set cache-pool cache_min_flush_age 300 # ceph osd pool set cache-pool cache_min_evict_age 300
- Enable
cache_target_dirty_ratio, which is the percentage of the cache pool containing dirty (modified) objects before the cache-tiering agent flushes them to the storage tier:# ceph osd pool set cache-pool cache_target_dirty_ratio .01 - Enable
cache_target_full_ratio, which is the percentage of the cache pool containing unmodified objects before the cache-tiering agent flushes them to the storage tier:# ceph osd pool set cache-pool cache_target_full_ratio .02Once you have completed these steps, the Ceph cache tiering setup should complete, and you can start adding workload to it:
- Create a temporary file of 500 MB that we will use to write to the
EC-pool, and which will eventually be written to acache-pool:# dd if=/dev/zero of=/tmp/file1 bs=1M count=500
..................Content has been hidden....................
You can't read the all page of ebook, please click here login for view all page.