I am exploring in ceph caching tier recently, considering a cache-tier (replicated) and a back storage-tier (erasure-coded), so chunks are stored in the OSDs in the erasure-coded storage tier, when a file has been requested to read, usually, all chunks in the storage tier would be copied to the cache tier, replicated, and stored in the OSDs in caching pool, but i was wondering would it be possible that if only partial chunks of the requested file be copied to cache? or it has to be a complete file? for example, a file using (7,4) erasure code (4 original chunks, 3 encoded chunks), when read it might be 4 required chunks are copied to cache, and i was wondering if it's possible to copy only 2 out of 4 required chunks to cache, and the users getting the other 2 chunks elsewhere (or assuming the client already has 2 chunks, they only need another 2 from ceph)? can the cache store partial chunks of a file?
Thanks in advance for any help!
Best,
Yu
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