----- Original Message ----- > From: "CHEVALIER Pierre" <pchevalier@xxxxxxxxxxx> > To: "Anuradha Talur" <atalur@xxxxxxxxxx> > Cc: gluster-users@xxxxxxxxxxx, "Pranith Kumar Karampuri" <pkarampu@xxxxxxxxxx>, "Ravishankar N" > <ravishankar@xxxxxxxxxx>, "Atin Mukherjee" <amukherj@xxxxxxxxxx> > Sent: Thursday, May 19, 2016 6:17:50 PM > Subject: Re: 2 nodes volume with existing data > > > Le 19/05/2016 12:06, Anuradha Talur a écrit : > > > > ----- Original Message ----- > >> From: "Atin Mukherjee" <amukherj@xxxxxxxxxx> > >> To: "CHEVALIER Pierre" <pchevalier@xxxxxxxxxxx>, gluster-users@xxxxxxxxxxx > >> Cc: "Pranith Kumar Karampuri" <pkarampu@xxxxxxxxxx>, "Ravishankar N" > >> <ravishankar@xxxxxxxxxx>, "Anuradha Talur" > >> <atalur@xxxxxxxxxx> > >> Sent: Tuesday, May 17, 2016 10:02:55 PM > >> Subject: Re: 2 nodes volume with existing data > >> > >> > >> > >> On 05/17/2016 01:59 PM, CHEVALIER Pierre wrote: > >>> Hi everyone, > >>> > >>> I have found a similar question in the ML but didn't find the answer I > >>> wanted. > >>> My situation is the following : > >>> We have 2 existing data storage unit with 72TB each, with 10TB left. > >>> Currently these storage unit are synced using rsync periodically. We > >>> want to tansform these 2 nodes into glusterfs bricks without loosing any > >>> data or deleting a node. > >>> > >>> I was thinking setting up the 2 nodes with glusterfs in replica this way > >>> : > >>> > >>> 1) Rsync server1/brick1 and server2/brick2 content > >>> 2) Create the gluster replica and start : > >>> gluster volume create volume1 replica 2 transport tcp server1:/brick1 > >>> server2:/brick1 > >>> gluster volume start volume1 > >> Gluster heavily depends on extended attributes for its business logic > >> and hence configuring a brick with existing data means that the extended > >> attributes would not be set for these files and hence this may not work > >> as per the expectation. > >> > >> Given that you have a restriction using another brick, I'd suggest you > >> to do the following: > >> > >> 1. Delete all the contents of server2/brick as this is a secondary copy > >> 2. Create a plain distributed volume in server2 with server2/brick1 > >> 2. Start the volume > >> 3. Mount the volume and then do copy the content from server1/brick1 to > >> the mount point. > >> 4. Probe server2 into the cluster > >> 5. Perform an add-brick with server1/brick by gluster volume add-brick > >> <volname> replica 2 <brick name> (Again make sure the content is deleted > >> first) > >> 6. This should trigger the self heal > > As of now converting a plain distribute volume to distribute replicate is > > not going to > > automatically heal the files. (We are working on a solution for this.) > > > > If you really want to go ahead with this method then I'd recommend you to > > do the following : > > > > 1) Stop I/O on your volume. > > 2) Add the new brick. > > 3) Stop and start your gluster volume > > 4) Trigger lookup on the files from mount point by doing find . | xargs > > stat on the mount point. > > > > This should trigger heals on the new brick. > Hi, > > OK this is good news, I wanted to avoid to have no backup of the content. > > So after that I mount the new volume as gluster fs and can start I/O on > it ? > > Thanks for these informations. Once you have completed the above mentioned steps, yes, you can mount the volume and start io on it. > > > > >> However since the data volume is very high, self heal can take a longer > >> time to sync and finish. > >> > >> Also with a two node setup prevention of split brains is not guaranteed. > >> An arbiter volume or a 3 way replica would be the solution to tackle > >> this problem. > >> > >> Since I am not an AFR expert, I'd like to get a sign off from AFR team > >> (In cc) before you try this out. > >> > >> ~Atin > >> > >>> Then, should I run a healing process, or stat each files in order to > >>> self heal ? > >>> > >>> What happens if there is a slight difference between the 2 nodes, > >>> mathematically if : > >>> server1/brick1= server2/brick1+delta > >>> > >>> Will the delta part impact server1, or will it be lost ? > >>> > >>> Maybe I worry for nothing, but as these 2 nodes host important data, I > >>> wanted to make sure that eveything is OK. > >>> > >>> Thanks for your help ! > >>> > >>> -- > >>> Pierre CHEVALIER > >>> > >>> > >>> > >>> _______________________________________________ > >>> Gluster-users mailing list > >>> Gluster-users@xxxxxxxxxxx > >>> http://www.gluster.org/mailman/listinfo/gluster-users > >>> > -- > Pierre CHEVALIER > > -- Thanks, Anuradha. _______________________________________________ Gluster-users mailing list Gluster-users@xxxxxxxxxxx http://www.gluster.org/mailman/listinfo/gluster-users
