Il giorno gio 4 feb 2021 alle ore 00:33 Simon Ironside < sironside@xxxxxxxxxxxxx> ha scritto: > > > On 03/02/2021 19:48, Mario Giammarco wrote: > > To labour Dan's point a bit further, maybe a RAID5/6 analogy is better > than RAID1. Yes, I know we're not talking erasure coding pools here but > this is similar to the reasons why people moved from RAID5 (size=2, kind > of) to RAID6 (size=3, kind of). I.e. the more disks you have in an array > (cluster, in our case) and the bigger those disks are, the greater the > chance you have of encountering a second problem during a recovery. > > Yes I know the motivations for raid6 but to simplify the use case I am comparing ceph size=2 to raid1. > > What I ask is this: what happens with min_size=1 and split brain, > > network down or similar things: do ceph block writes because it has no > > quorum on monitors? Are there some failure scenarios that I have not > > considered? > > It sounds like in your example you would have 3 physical servers in > total. So would you have both a monitor and OSDs processes on each server? > > Yes sorry if it was not clear: - three servers - three monitors - three managers - 6 osd (two disks per server) > If so, it's not really related to min_size=1 but to answer your question > you could lose one monitor and the cluster would continue. Losing a > second monitor will stop your cluster until this is resolved. In your > example setup (with colocated mons & OSDs) this would presumably also > mean you'd lost two OSDs servers too so you'd have bigger problems. > > Losing the switch means monitors are up but cannot communicate so they should stop? _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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