On Fri, Feb 16, 2018 at 5:21 PM, Matt Benjamin <mbenjami@xxxxxxxxxx> wrote: > Hi, > > On Fri, Feb 16, 2018 at 8:16 PM, Yehuda Sadeh-Weinraub > <yehuda@xxxxxxxxxx> wrote: >> Now that the sync-to-the-cloud work is almost complete, I was thinking >> a bit and did some research about bi-directional sync. The big >> difficulty I had with the syncing from the cloud process is the need >> to rework the whole data sync paths where we identify changes. These >> are quite complicated, and these kind of changes are quite a big >> project. I'm not quite sure now that this is needed. >> What I think we could do in a relatively easy (and less risky) way is >> that instead of embedding a new mechanism within the sync logic, we >> can create a module that turns upstream cloud changes into the >> existing rgw logs: that is, data log, and bucket index logs (no >> metadata log needed). > > This is clean, but naively seems to induce a lot of transient OMAP i/o? Less than what we have on a regular rgw zone. One thing to think about is how to deal with resharding on these buckets. Yehuda > > In this way we break the problem into two >> separate issues, where one of the issues is already solved. The >> ingesting rgw could then do the same work it is doing with regular >> zones (fetching these logs, and pulling the data from a remote >> endpoint) -- albeit with various slight changes that are required >> since we can't have some of the special apis that we created to assist >> us. >> We'll need to see how these could be replaced and what will be the >> trade offs, but we'll need to do that anyway with any solution. >> The changes discovery module that will turn remote cloud changes into >> local logs could do it by either polling the remote endpoints, or (for >> S3 for example) could use buckets notifications mechanism. > > If AWS makes this efficient, sounds reasonable. > > It will >> build its local changes logs by setting new entries on them according >> to the changes it identifies. The radosgw zone that will sync from the >> cloud will have two endpoints one that will be used to fetch the the >> logs, and another one that will be used to sync in the data. >> I'm a bit simplifying it, there are a few more issues there, but >> that's the gist of it. >> >> Any thoughts? >> >> Yehuda > > Matt > > -- > > Matt Benjamin > Red Hat, Inc. > 315 West Huron Street, Suite 140A > Ann Arbor, Michigan 48103 > > http://www.redhat.com/en/technologies/storage > > tel. 734-821-5101 > fax. 734-769-8938 > cel. 734-216-5309 -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
