On Wed, Oct 16, 2013 at 8:01 AM, Kasper Dieter <dieter.kasper@xxxxxxxxxxxxxx> wrote: > Hi Greg, > > on http://comments.gmane.org/gmane.comp.file-systems.ceph.user/1705 > I found a statement from you regarding snapshots on cephfs: > > ---snip--- > Filesystem snapshots exist and you can experiment with them on CephFS > (there's a hidden ".snaps" folder; you can create or remove snapshots > by creating directories in that folder; navigate up and down it, etc). > ---snip--- > > Can you please explain in more detail or with example CMDs how to create/list/remove snapshots in CephFS ? As Shain described, you just do mkdir/ls/rmdir in the .snaps folder. > I assume they will be created on a directory level ? Snapshots cover the entire subtree starting with the folder you create them from. If a user puts it in their home directory, there will be a snapshot of all their document folders, source code folders, etc as well. > How will the CephFS snapshots cohere with the underlaying pools ? > (e.g. using cephfs /mnt/cephfs/dir-1/dir2 set_layout -p 18) CephFS snapshots store some metadata directly in the directory object (in the metadata pool), but the file data is stored using RADOS self-managed snapshots on the regular objects. If you specify that a file/folder goes in a different pool, the snapshots also live there as a matter of course. Separately: 1) you will probably have a better time specifying layouts using the ceph.layout virtual xattrs if your installation is new enough. (There's no new functionality there, but it's a lot friendlier and less fiddly than the cephfs tool is.) 2) Keep in mind that snapshots are noticeably less stable in use than the regular filesystem features. The ability to create new ones is turned off by default in the "next" branch (admins can enable them with a monitor command). -Greg Software Engineer #42 @ http://inktank.com | http://ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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