On Tue, 25 Nov 2014, Tomasz Kuzemko wrote: > Hello, > as far as I can tell, Ceph does not make any guarantee that reads from an > object return what was actually written to it. In other words, it does not > check data integrity (except doing deep-scrub once every few days). > Considering the fact that BTRFS is not production-ready, not many people use > Ceph on top of ZFS, then the only option to have some sort of guarantee of > integrity is to enable "filestore sloppy crc" option. Unfortunately the docs > aren't too clear about this matter and "filestore sloppy crc" is not even > documented, which is weird considering it's merged since Emperor. > > Getting back to my actual question - what is the state of "filestore sloppy > crc"? Does someone actually use it in production? Are there any > considerations one should make before enabling it? Is it safe to enable it > on an existing cluster? We enable it in our automated QA, but do not know of anyone using it in production and have not recommended it for that. It is not intended to be particularly fast and we didn't thoroughly analyze the xattr size implications on the file systems people may run on. Also note that it simply fails (crashes) the OSD when it detects an error and has no integration with scrub, which makes it not particularly friendly. Note that I am working on a related patch set that will keep a persistent checksum of the entire object that will interact directly with deep scrubs. It will not be as fine-grained but is intended for production use and will cover the bulk of data that sits unmodified at rest for extended periods. sage _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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