| I'm still not sure which exact Ceph concept you are referring to. Thre is the "minimum allocation size" [1], but that is currently 4 KB (not MB). There is also striping [2], which is the equivalent of RAID-10 functionality to split a large file into independent segments that can be written in parallel.
Perhaps you are referring to RGW's default stripe size of 4 MB [3]? If yes, I can understand your point about one 4 MB RADOS object being erasure-coded to e.g. 6 = 4+2 "parity chunks", making it < 1 MB writes that are not efficient on HDDs. But would you not simply raise `rgw_obj_stripe_size` to address that, according to the k you choose? E.g. 24 MB? You mention it can be changed, but I don't understand the "but still the tuning is based on the size of the block to be coded" part, (why) is that a problem? Also, how else would you do it when designing EC writes? Thanks! [1]: https://docs.ceph.com/en/squid/rados/configuration/bluestore... [2]: https://docs.ceph.com/en/squid/architecture/#data-striping [3]: https://docs.ceph.com/en/squid/radosgw/config-ref/#confval-r... |