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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