On Wed, May 28, 2014 at 10:05 AM, Loic Dachary <loic@xxxxxxxxxxx> wrote: > > > On 28/05/2014 15:35, Koleos Fuskus wrote: >> >> >>> 1. What will be erasure model unit? Is it a pool or a placement group? I cannot see the best option here yet, probably because my inexperience with Ceph. >> >> A pool. >> OK. this is what I thought but some things are not clear enough. I am deploying Ceph to toying a bit more. >> >> >>> 3. Metadata: Jerasure creates metadata files. How are those files stored in ceph (what kind of >> Jerasure does not create a metadata file. >> >> It does on my machine! at least with jerasure 1.2 on mac os :) > > If you mean the files that are created by the command line examples provided with jerasure (1.2 or 2), they are not required and only meant for test purposes. > > Cheers > >> >> >> >> >> I proposed an update to the documentation to clarify this : https://github.com/ceph/ceph/pull/1856 . Does it look sensible to you ? >> >> Recently while considering a hardware update on the Ceph cluster I've been thinking about the durability model of the new OSD nodes once the cluster is done migrating over. So I came looking through these old emails. I think it might be very useful to have a web tool that describes (or visualizes) the current cluster durability model, or better yet helps you play with the variables to visualize the changes. If we can formulate the rules model based on some common variables (about machines, OSDs, racks) and replication rules (count or erasure coding paramaters). Then we can spit out useful information like: - How many nodes / racks / osds do you need to lose to have data offline - What percentage of data is going to be unavailable if you lose X resources - What's the probability of data loss over time - How does the readability model impact your cluster network traffic, repair traffic I think it would be stair-forward to build the web app. In fact, I'll volunteer myself for that task. Before we start that I would suggest we try to get the model in something like Google Docs Sheets so we can use it as a basis. -- Milosz Tanski CTO 16 East 34th Street, 15th floor New York, NY 10016 p: 646-253-9055 e: milosz@xxxxxxxxx -- 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
