“read-only xlator is loaded at gluster server (brick) stack. so once the volume is in place, you'd need to enable read-only option using volume set and then you should be able to mount the volume which would provide you the read-only access.”
OK, so fair enough, but is the physical volume on which the brick resides allowed to be on a r/o filesystem? Again, it’s not just whether Gluster considers the volume to be read-only to clients, but whether the gluster brick and its underlying medium can be read-only. From: Atin Mukherjee [mailto:[email protected]] Sent: Tuesday, March 21, 2017 9:42 AM To: Mackay, Michael Cc: Samikshan Bairagya; [email protected] Subject: (nwl) Re: [Gluster-devel] Read-only option for a replicated (replication for fail-over) Gluster volume On Tue, Mar 21, 2017 at 6:06 PM, Mackay, Michael <[email protected]<mailto:[email protected]>> wrote: Samikshan, Thanks for your suggestion. From what I understand, the read-only feature (which I had seen and researched) is a client option for mounting the filesystem. Unfortunately, we need the filesystem itself to be set up read-only, so that no one can modify it - in other words, we need to make sure that no client can mount it read/write. So, it has to be set up and started as r/o, and then the clients have no choice but to get a r/o copy. read-only xlator is loaded at gluster server (brick) stack. so once the volume is in place, you'd need to enable read-only option using volume set and then you should be able to mount the volume which would provide you the read-only access. Thanks Mike -----Original Message----- From: Samikshan Bairagya [mailto:[email protected]<mailto:[email protected]>] Sent: Monday, March 20, 2017 3:52 PM To: Mackay, Michael Cc: [email protected]<mailto:[email protected]> Subject: Re: [Gluster-devel] Read-only option for a replicated (replication for fail-over) Gluster volume On 03/21/2017 12:38 AM, Mackay, Michael wrote: > Gluster folks: > > Our group has a need for a distributed filesystem, like Gluster, that can be > mounted by clients as read-only. We wish to have the ability to seamless > switch over to an alternate source of this read-only data if the default > source fails. > The reason for this ROFS is so that every client can get access to > applications and data that we want to ensure stays the same (unmodifiable) > for an entire system delivery life cycle. To date we've used read-only NFS > mounts reasonably well, but its failover performance is not at all great. > > We also don't want a "WORM" sort of arrangement - we want to prevent any and > all writes to the volume once it's up and shared. > > So, under the "how hard could it be" mantra, we took version 3.7.15 and poked > around a bit until we got it to do just what we want. It was a minor mod to > 'xlators/features/index/src/index.c' and > 'xlators/storage/posix/src/posix-helpers.c', along with a "force" option when > doing the volume start command. > > We would happily share the specific changes, and they seem to fit in the > 3.10.0 code base too; the question for the group is, would such a capability > be of interest to the Gluster baseline? Possibly a precursor question (since > I don't have much experience in gluster-devel at all, so please forgive my > approach if it's wrong) is, to whom should I pose this question, if it's not > to this group? > > Thanks for your time and I'd be happy to provide any further information. > Hi Mike, Have you checked the 'features.read-only' volume option. Apparently you can set it to on/off depending on whether you want your volume to be read-only or not. By default it is set to 'off'. The following would make your volume read-only for all clients accessing it: # gluster volume set <VOLNAME> features.read-only on Hope that helped. ~ Samikshan _______________________________________________ Gluster-devel mailing list [email protected]<mailto:[email protected]> http://lists.gluster.org/mailman/listinfo/gluster-devel -- ~ Atin (atinm)
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