Saludos! In our article earlier talked about how to make a cluster, well, the introduction to the how. We define that going to do with Ubuntu Jaunty, into two groups with 8GB of RAM and 4 cores and two SATA hard drives.

This time we will see how to create clustered storage, that is the basis for everything else.

The first thing I must say is that this step is crucial and has also been the most complex that I have encountered throughout this Laboratory.

My first idea was to use iSCSI to make a Iraide-1 and format it with GFS/OCFS2. This was working well until the point where attempts to mount the device Iraide in my two hosts at the same time. That ruled all, you could not open the device source / dev/sda1 twice at the same time. Then I had to pull back and find another solution.

This was DRBD. This wonderful development allows a RAID-1 of 2 teams (for now) network. It provides the synchronization and replication block-level changes both discs.

Then he tried to share in each host their own DRBD device using iSCSI. Another failure. Within the same computer everything works perfectly, with all its virtual machines, but when I wanted to do the same in the other host and virtual machines host1 to agree with those of host2, everything failed. They did not speak at all, since they were different devices for the cluster.

Then, after thinking, and to comfort a little, I set the maximum write speed of my disk was 20MB / s random access, and my internal network is 1GB, so I could use NFS within each host to give you access to the storage device to each node, without having speed problems.

But my idea is, and I do someday when I do that, write an update. The idea is to make a GFS2/OCFS2 on DRBD or iSCSI over on a Iraide-1.

Finally, it came time to choose the file system. If you attempt to cluster in which all nodes can be written, putting a normal file system like ext3, xfs, reiserfs or similar device to ride in two or more nodes and write to them all and will be corrupted to reformat. To do that requires a file system for clusters. Initially probe GFS2, but the configuration complexity made me give up. Probe OCFS2 then that I found very easy, so that was the big winner.

Now I have finished the introduction to this article, we'll what we want, which is to make everything.