I'm new, too, and I guess I just need a little clarification on Greg's statement. The RBD filesystem is mounted to multiple VM servers, say, in a Proxmox cluster, and as long as any one VM image file on that filesystem is only being accessed from one node of the cluster, everything will work, and that's the way shared storage is intended to work within Ceph/RBD. Correct? I can understand things blowing up if the same VM image file is being accessed from multiple nodes in the cluster, and that's where a clustered filesystem comes into play. I guess in my mind/world I was envisioning a group of VM servers using one large RBD volume, that is mounted to each VM server in the group, to store the VM images for all the VM's in the group of VM servers. This way the VM's could migrate to any VM server in the group using the RBD volume. No? Brad -----Original Message----- From: ceph-users-bounces@xxxxxxxxxxxxxx [mailto:ceph-users-bounces@xxxxxxxxxxxxxx] On Behalf Of Gregory Farnum Sent: Friday, March 01, 2013 2:13 PM To: Karsten Becker Cc: ceph-users@xxxxxxxx Subject: Re: Concurrent access to Ceph filesystems On Fri, Mar 1, 2013 at 1:53 PM, Karsten Becker <karsten.becker@xxxxxxxxxxx> wrote: > Hi, > > I'm new to Ceph. I currently find no answer in the official docs for > the following question. > > Can Ceph filesystems be used concurrently by clients, both when > accessing via RBD and CephFS? Concurrently means in terms of multiple > clients accessing an writing on the same Ceph volume (like it is > possible with OCFS2) and extremely, in the same file at the same time. > Or is Ceph a "plain" distributed filesystem? CephFS supports this very nicely, though it is of course not yet production ready for most users. RBD provides block device semantics - you can mount it from multiple hosts, but if you aren't using cluster-aware software on top of it you won't like the results (eg, you could run OCFS2 on top of RBD, but running ext4 on top of it will work precisely as well as doing so would with a regular hard drive that you somehow managed to plug into two systems at once). -Greg _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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