On Fri, Jun 16, 2023 at 5:13 PM Casey Bodley <cbodley@xxxxxxxxxx> wrote: > > On Fri, Jun 16, 2023 at 3:21 AM Jiffin Thottan <jthottan@xxxxxxxxxx> wrote: > > > > Hi, > > > > I am planning to support read localise feature for RGW servers similar to what RBD volumes support. From code reading, it looks to pass "librados::OPERATION_LOCALIZE_READS" before sending the request to RADOS. I have created a tracker issue for this feature https://tracker.ceph.com/issues/61701, this will be per server config option. I don't know about any other technical hurdles in implementing this feature. Please share your thoughts on the same. > > > > Thanks and regards, > > Jiffin > > thanks Jiffin, > > that sounds simple enough, though rgw issues librados reads in many > different places that would need to manage this flag > > i'm curious why this is a per-op flag, rather than a global librados > setting. is there a reason that rgw would only want *some* of its > reads localized? are there any implications for read-after-write > consistency that we need to worry about here? Hi Casey, I'm not aware of any read-after-write or other consistency implications. Read-from-replica is safe for general use since Octopus (OSD-side issues were fixed in [1]). Ultimately all flags are per-op. The reason that there is no global librados setting for BALANCE_READS and LOCALIZE_READS seems to be a combination of a) the fact that these flags could only be used in special circumstances in the past and b) the fact that librados doesn't have a generic API for applying a given flag globally like it does for applying a given snapshot ID/context to all reads/writes. [1] https://github.com/ceph/ceph/pull/32381 Thanks, Ilya _______________________________________________ Dev mailing list -- dev@xxxxxxx To unsubscribe send an email to dev-leave@xxxxxxx
