Hi all,
I have a ceph cluster with 4+2 EC used as a secondary storage system for
offloading big files from another storage system. Even if most of the
files are big (at least 50MB), we have also some small objects - less
than 4MB each. The current storage usage is 358TB of raw data and 237TB
of 'usable' data which means an overhead of 66%.
I was wondering if I can get more storage efficiency if I can get rid of
all the small files by moving them on other storage systems. My
understanding is that every file is splitted into stripe_unit chunks and
then mapped into ceph objects which have a size of 4MB per object. So if
I have a file with a size of 1MB, the file will be splitted into 4 x
256KB chunks, then added another 2 x 256KB chunks as overhead and every
chunk will be mapped into a ceph object of 4MB size. This means a 1MB
file will be stored as 6 ceph objects i.e the storage usage will be
24MB. Not sure if my understanding is correct though...
Do you have any suggestions on this topic ? Does it really worth it to
move the small files from ceph ? If yes, what is the minimum file size
which I can safely store in ceph without loosing too much storage ?
Thanks.
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