Hi Edward thanks for your explanation!
Yes you are right. I just came across sebastien han's post, using nfs on top of rbd( http://www.sebastien-han.fr/blog/2012/07/06/nfs-over-rbd/) I will try this method. On Mon, May 2, 2016 at 11:14 AM, Edward Huyer <[email protected]> wrote: > Mapping a single RBD on multiple servers isn’t going to do what you want > unless you’re putting some kind of clustered filesystem on it. Exporting > the filesystem via an NFS server will generally be simpler. > > > > You’ve already encountered one problem with sharing a block device without > a clustered filesystem: One server doesn’t know when some other server has > changed something, so a given server will only show changes it has made > unless you somehow refresh the server’s knowledge (with a remount, for > example). > > > > A related but much bigger problem comes with multiple servers are writing > to the same block device. Because no server is aware of what the other > servers are doing, it’s essentially guaranteed that you’ll have one server > partially overwriting things another server just wrote, resulting in lost > data and/or a broken filesystem. > > > > ----- > > Edward Huyer > > School of Interactive Games and Media > > Golisano 70-2373 > > 152 Lomb Memorial Drive > > Rochester, NY 14623 > > 585-475-6651 > > [email protected] > > > > Obligatory Legalese: > > The information transmitted, including attachments, is intended only for > the person(s) or entity to which it is addressed and may contain > confidential and/or privileged material. Any review, retransmission, > dissemination or other use of, or taking of any action in reliance upon > this information by persons or entities other than the intended recipient > is prohibited. If you received this in error, please contact the sender and > destroy any copies of this information. > > > > *From:* ceph-users [mailto:[email protected]] *On Behalf > Of *yang sheng > *Sent:* Monday, May 02, 2016 9:47 AM > *To:* Sean Redmond <[email protected]> > *Cc:* ceph-users <[email protected]> > *Subject:* Re: [ceph-users] can I attach a volume to 2 servers > > > > hi Sean > > > > thanks for your reply > > > > I think the ceph and openstack works fine for me. I can attach a bootable > volume to vm. > > > > I am right now trying to attach the volumes to physical servers > (hypervisor nodes) and share some data among hypervisors (based on the > docs, nova evacuate function require all hypervisors share instance files). > > > > In the doc, they are using a NFS cluster. I am wondering if i can use the > ceph volume instead of NFS. > > > > (I have created a volume and attached the volume to 2 hypervisors (A and > B). but when I write something in server A, the server B couldn't see the > file. I have de-attach and re-attach the volume on server B. ) > > > > > > > > On Mon, May 2, 2016 at 9:34 AM, Sean Redmond <[email protected]> > wrote: > > Hi, > > > > You could set the below to create ephemeral disks as RBD's > > > > [libvirt] > > libvirt_images_type = rbd > > > > On Mon, May 2, 2016 at 2:28 PM, yang sheng <[email protected]> wrote: > > Hi > > > > I am using ceph infernalis. > > > > it works fine with my openstack liberty. > > > > I am trying to test nova evacuate. > > > > All the vms' volumes are shared among all compute nodes. however, the > instance files (/var/lib/nova/instances) are in each compute node's local > storage. > > > > Based on redhat docs( > https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux_OpenStack_Platform/6/html/Administration_Guide/section-evacuation.html), > nova evacuate require sync the instance files as well and they created a > NFS cluster. > > > > Since ceph is also shared among all nodes as well, I was thinking to > create a volume in ceph and attach this volume to all compute nodes. > > > > just wondering is this doable? > > > > (I have already attached this volume to 2 servers, server A and server B. > If I write something in server A, seems it is not visible to server B. I > have to re-attach the volume to server B so that server B can see it.) > > > > _______________________________________________ > ceph-users mailing list > [email protected] > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com > > > > >
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