Which gluster version are you using? Better peer identification feature (available 3.6 onwards) should tackle this problem IMO. ~Atin On 07/02/2015 10:05 AM, Rarylson Freitas wrote: > Hi, > > Recently, my company needed to change our hostnames used in the Gluster > Pool. > > In a first moment, we have two Gluster Nodes called storage1 and storage2. > Our volumes used two bricks: storage1:/MYVOLYME and storage2:/MYVOLUME. We > put the storage1 and storage2 IPs in the /etc/hosts file of our nodes and > in our client servers. > > After some time, more client servers started to using Gluster and we > discovered that using hostnames without domain (using /etc/hosts) in all > client servers is a pain in the a$$ :(. So, we decided to change them to > something like storage1.mydomain.com and storage2.mydomain.com. > > Remember that, at this point, we had already some volumes (with bricks): > > $ gluster volume info MYVOL > [...] > Brick1: storage1:/MYDIR > Brick1: storage2:/MYDIR > > For simplicity, let's consider that we had two Gluster Nodes, each one with > the following entries in /etc/hosts: > > 10.10.10.1 storage1 > 10.10.10.2 storage2 > > To implement the hostname changes, we've changed the etc hosts file to: > > 10.10.10.1 storage1 storage1.mydomain.com > 10.10.10.2 storage2 storage2.mydomain.com > > And we've run in storage1: > > $ gluster peer probe storage2.mydomain.com > peer probe: success > > Everything works well during some time, but the glusterd starts to fail > after any reboot: > > $ service glusterfs-server status > glusterfs-server start/running, process 14714 > $ service glusterfs-server restart > glusterfs-server stop/waiting > glusterfs-server start/running, process 14860 > $ service glusterfs-server status > glusterfs-server stop/waiting > > To start the service again, it was necessary to rollback the hostname1 > config to storage2 in /var/lib/glusterd/peers/OUR_UUID. > > After some try and error, we discovered that if we change the order of the > entries in /etc/hosts and repeat the process, everything worked. > > It is, from: > > 10.10.10.1 storage1 storage1.mydomain.com > 10.10.10.2 storage2 storage2.mydomain.com > > To: > > 10.10.10.1 storage1.mydomain.com storage1 > 10.10.10.2 storage2.mydomain.com storage2 > > And run: > > gluster peer probe storage2.mydomain.com > service glusterfs-server restart > > So we've checked the Glusterd debug log and checked the GlusterFS source > code and discovered that the big secret was the function > glusterd_friend_find_by_hostname, in the file > xlators/mgmt/glusterd/src/glusterd-utils.c. This function is called for > each brick that isn't a local brick and does the following things: > > - It checks if the brick hostname is equal to some peer hostname; > - If it's, this peer is our wanted friend; > - If not, it gets the brick IP (resolves the hostname using the function > getaddrinfo) and checks if the brick IP is equal to the peer hostname; > - It is, we could run gluster peer probe 10.10.10.2. Once the brick > IP (storage2 resolves to 10.10.10.2) would have equal to the peer > "hostname" (10.10.10.2); > - If it's, this peer is our wanted friend; > - If not, gets the reverse of the brick IP (using the function > getnameinfo) and checks if the brick reverse is equal to the peer > hostname; > - This is why changing the order of the entries in /etc/hosts worked > as an workaround for us; > - If not, returns and error (and Glusterd will fail). > > However, we think that comparing the brick IP (resolving the brick > hostname) and the peer IP (resolving the peer hostname) would be a simpler > and more comprehensive solution. Once both brick and peer will have > difference hostnames, but the same IP, it would work. > > The solution could be: > > - It checks if the brick hostname is equal to some peer hostname; > - If it's, this peer is our wanted friend; > - If not, it gets both the brick IP (resolves the hostname using the > function getaddrinfo) and the peer IP (resolves the peer hostname) and, > for each IP pair, check if a brick IP is equal to a peer IP; > - If it's, this peer is our wanted friend; > - If not, returns and error (and Glusterd will fail). > > What do you think about it? > -- > > *Rarylson Freitas* > Computer Engineer > > > > _______________________________________________ > Gluster-devel mailing list > Gluster-devel@xxxxxxxxxxx > http://www.gluster.org/mailman/listinfo/gluster-devel > -- ~Atin _______________________________________________ Gluster-devel mailing list Gluster-devel@xxxxxxxxxxx http://www.gluster.org/mailman/listinfo/gluster-devel
