I would say everyone recommends at least 3 monitors and since they need to be 1,3,5 or 7 I always read that as 5 is the best number (if you have 5 servers in your cluster). The other reason is high availability since the MONs use Paxos for the quorum and I like to have 3 in the quorum you need 5 to be able to do maintenance. (2 out of 3, 3 out of 5… ) So if you are doing maintenance on a mon host in a 5 mon cluster you will still have 3 in the quorum.
From: huxia...@horebdata.cn <huxia...@horebdata.cn> Date: Friday, February 12, 2021 at 8:42 AM To: Freddy Andersen <fre...@cfandersen.com>, Marc <m...@f1-outsourcing.eu>, Michal Strnad <michal.str...@cesnet.cz>, ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Re: Backups of monitor Why 5 instead of 3 MONs are required? huxia...@horebdata.cn From: Freddy Andersen Date: 2021-02-12 16:05 To: huxia...@horebdata.cn; Marc; Michal Strnad; ceph-users Subject: Re: [ceph-users] Re: Backups of monitor I would say production should have 5 MON servers From: huxia...@horebdata.cn <huxia...@horebdata.cn> Date: Friday, February 12, 2021 at 7:59 AM To: Marc <m...@f1-outsourcing.eu>, Michal Strnad <michal.str...@cesnet.cz>, ceph-users <ceph-users@ceph.io> Subject: [ceph-users] Re: Backups of monitor Normally any production Ceph cluster will have at least 3 MONs, does it reall need a backup of MON? samuel huxia...@horebdata.cn From: Marc Date: 2021-02-12 14:36 To: Michal Strnad; ceph-users@ceph.io Subject: [ceph-users] Re: Backups of monitor So why not create an extra start it only when you want to make a backup, wait until it is up to date, stop it and then stop it to back it up? > -----Original Message----- > From: Michal Strnad <michal.str...@cesnet.cz> > Sent: 11 February 2021 21:15 > To: ceph-users@ceph.io > Subject: [ceph-users] Backups of monitor > > Hi all, > > We are looking for a proper solution for backups of monitor (all maps > that they hold). On the internet we found advice that we have to stop > one of monitor, back it up (dump) and start daemon again. But this is > not right approach due to risk of loosing quorum and need of > synchronization after monitor is back online. > > Our goal is to have at least some (recent) metadata of objects in > cluster for the last resort when all monitors are in very bad > shape/state and we could start any of them. Maybe there is another > approach but we are not aware of it. > > We are running the latest nautilus and three monitors on every cluster. > > Ad. We don't want to use more monitors than thee. > > > Thank you > Cheers > Michal > -- > Michal Strnad > _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io _______________________________________________ ceph-users mailing list -- ceph-users@ceph.io To unsubscribe send an email to ceph-users-le...@ceph.io
