On Tue, May 28, 2019 at 08:57:17AM -0400, Erik McCormick wrote:
On Tue, May 28, 2019, 8:29 AM Bernd Bausch <berndbausch@gmail.com> wrote:
Thanks for clarifying this Erik. Let me point out then that the release notes [1] are worded rather unequivocally, and what you are saying contradicts them:
RBD driver has added multiattach support. It should be noted that replication and multiattach are mutually exclusive, so a single RBD volume can only be configured to support one of these features at a time. Additionally, RBD image features are not preserved which prevents a volume being retyped from multiattach to another type. This limitation is temporary and will be addressed soon.
Bernd.
I haven't even looked at Stein yet so I could be wrong, but I thin this is referring to replication like RBD mirroring. There's still an issue in Ceph, as far as I know, where ceph's object replication would have a problem with multi-attach. I haven't come across any Ceph release note to say this has been addressed.
Hopefully someone from the Cinder team can straighten us out.
-Erik
Multiattach support has indeed been enabled for RBD as of the Stein release. Though there are the known caveats that you point out. I thought there was a pending patch to add some details on this to to the RBD driver configuration reference, but I am not finding anything at the moment. I don't have all the details on that myself, but hopefully one of the RBD driver maintainers can chime in here with better details. Sean