Hey Andre, Clients actually have access to more information than just the crushmap, which includes temporary PG mappings generated when a backfill is pending, as well as upmap items which override CRUSH's placement decision. You can see these in "ceph osd dump", for example. Josh On Mon, Jan 27, 2025 at 6:00 AM Andre Tann <atann@xxxxxxxxxxxx> wrote: > > Hi list, > > I have a problem understanding on how crush works when the crush map > changes. > > Let's take a pool with some data in it, and a crush map that enables a > client to calculate itself where a particular chunk is stored. > > Now we add more OSDs, which means, the crush map changes. Now most > objects are misplaced, given the new crush map. > > If the clients wants a particular chunk, it takes the modified map, but > as the chunk is misplaced, it won't find it where the crush algorithm > points to. > > How can the client know which crush map to consider when doing the > calculation? > Do the clients keep several versions of the map, and try them one after > the other? > > Thanks for some hints on this. > -- > Andre Tann > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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