Thanks Janne. I actually meant that the RW mount is unmounted already - sorry about the confusion. - Shridhar On Mon, 4 May 2020 at 00:35, Janne Johansson <icepic.dz@xxxxxxxxx> wrote: > Den mån 4 maj 2020 kl 05:14 skrev Void Star Nill <void.star.nill@xxxxxxxxx > >: > >> One of the use cases (e.g. machine learning workloads) for RBD volumes in >> our production environment is that, users could mount an RBD volume in RW >> mode in a container, write some data to it and later use the same volume >> in >> RO mode into a number of containers in parallel to consume the data. >> >> I am trying to test this scenario with different file systems (ext3/4 and >> xfs). I have an automated test code that creates a volume, maps it to a >> node, mounts in RW mode and write some data into it. Later the same volume >> is mounted in RO mode in a number of other nodes and a process reads from >> the file. >> > > Is the RW unmounted or not? You write "stopped writing" but that doesn't > clearly > indicate if you make it impossible or just "I ask it to not make much IO". > Given that many filesystems are doing very lazy writes, caches a lot and > so on, > it would be very important to make sure 1) ALL writes are done, which is > easiest with > umount I think and 2) that mounting clients knows can't write to it at > all, or otherwise > as someone said, it might still be updating some metainfo like the > journals or > "last mounted on /X" or whatever magic fs's store even while not altering > the files > inside the fs. > > It's kind of hard to tell filesystems that are accustomed to being in > charge of all > mounted instances to sit in the back seat and not be allowed to control > stuff. > > -- > May the most significant bit of your life be positive. > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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