----- Original Message -----> From: "Atin Mukherjee" <amukherj at redhat.com> > To: "CHEVALIER Pierre" <pchevalier at imajing.org>, gluster-users at gluster.org > Cc: "Pranith Kumar Karampuri" <pkarampu at redhat.com>, "Ravishankar N" <ravishankar at redhat.com>, "Anuradha Talur" > <atalur at redhat.com> > Sent: Tuesday, May 17, 2016 10:02:55 PM > Subject: Re: [Gluster-users] 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 healAs 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.> > 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 at gluster.org > > http://www.gluster.org/mailman/listinfo/gluster-users > > >-- Thanks, Anuradha.
Le 19/05/2016 12:06, Anuradha Talur a ?crit :> > ----- Original Message ----- >> From: "Atin Mukherjee" <amukherj at redhat.com> >> To: "CHEVALIER Pierre" <pchevalier at imajing.org>, gluster-users at gluster.org >> Cc: "Pranith Kumar Karampuri" <pkarampu at redhat.com>, "Ravishankar N" <ravishankar at redhat.com>, "Anuradha Talur" >> <atalur at redhat.com> >> Sent: Tuesday, May 17, 2016 10:02:55 PM >> Subject: Re: [Gluster-users] 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.> >> 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 at gluster.org >>> http://www.gluster.org/mailman/listinfo/gluster-users >>>-- Pierre CHEVALIER -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://www.gluster.org/pipermail/gluster-users/attachments/20160519/a128f599/attachment.html>
----- Original Message -----> From: "CHEVALIER Pierre" <pchevalier at imajing.org> > To: "Anuradha Talur" <atalur at redhat.com> > Cc: gluster-users at gluster.org, "Pranith Kumar Karampuri" <pkarampu at redhat.com>, "Ravishankar N" > <ravishankar at redhat.com>, "Atin Mukherjee" <amukherj at redhat.com> > Sent: Thursday, May 19, 2016 6:17:50 PM > Subject: Re: [Gluster-users] 2 nodes volume with existing data > > > Le 19/05/2016 12:06, Anuradha Talur a ?crit : > > > > ----- Original Message ----- > >> From: "Atin Mukherjee" <amukherj at redhat.com> > >> To: "CHEVALIER Pierre" <pchevalier at imajing.org>, gluster-users at gluster.org > >> Cc: "Pranith Kumar Karampuri" <pkarampu at redhat.com>, "Ravishankar N" > >> <ravishankar at redhat.com>, "Anuradha Talur" > >> <atalur at redhat.com> > >> Sent: Tuesday, May 17, 2016 10:02:55 PM > >> Subject: Re: [Gluster-users] 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 at gluster.org > >>> http://www.gluster.org/mailman/listinfo/gluster-users > >>> > -- > Pierre CHEVALIER > >-- Thanks, Anuradha.