Yes, data that is not synced is not guaranteed to be written to disk, this is consistent with POSIX semantics. Paul -- Paul Emmerich Looking for help with your Ceph cluster? Contact us at https://croit.io croit GmbH Freseniusstr. 31h 81247 München www.croit.io Tel: +49 89 1896585 90 On Mon, Jan 27, 2020 at 9:11 PM Håkan T Johansson <f96hajo@xxxxxxxxxxx> wrote: > > > Hi, > > for test purposes, I have set up two 100 GB OSDs, one > taking a data pool and the other metadata pool for cephfs. > > Am running 14.2.6-1-gffd69200ad-1 with packages from > https://mirror.croit.io/debian-nautilus > > Am then running a program that creates a lot of 1 MiB files by calling > fopen() > fwrite() > fclose() > for each of them. Error codes are checked. > > This works successfully for ~100 GB of data, and then strangely also succeeds > for many more 100 GB of data... ?? > > All written files have size 1 MiB with 'ls', and thus should contain the data > written. However, on inspection, the files written after the first ~100 GiB, > are full of just 0s. (hexdump -C) > > > To further test this, I use the standard tool 'cp' to copy a few random-content > files into the full cephfs filessystem. cp reports no complaints, and after > the copy operations, content is seen with hexdump -C. However, after forcing > the data out of cache on the client by reading other earlier created files, > hexdump -C show all-0 content for the files copied with 'cp'. Data that was > there is suddenly gone...? > > > I am new to ceph. Is there an option I have missed to avoid this behaviour? > (I could not find one in > https://docs.ceph.com/docs/master/man/8/mount.ceph/ ) > > Is this behaviour related to > https://docs.ceph.com/docs/mimic/cephfs/full/ > ? > > (That page states 'sometime after a write call has already returned 0'. But if > write returns 0, then no data has been written, so the user program would not > assume any kind of success.) > > Best regards, > > Håkan > _______________________________________________ > 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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