[Ocfs2-users] Missing something basic...

[Luis Freitas]

  For test and research you could look into DRDB, which should be rather stable. 
   
  If you are adventurous, you could try running RAID1 over two iSCSI targets, or use ATA over ethernet. I am pretty sure that the linux md tools are not cluster aware. Dont know if LVM2 has mirroring.
   
  I dont recomend any of these two options for running a Oracle database, even on a test environment. 
   
  Randy Ramsdell <rramsdell at livedatagroup.com> wrote:
  Benjamin Smith wrote:
> I'm stumped. I'm doing some research on clustered file systems to be deployed 
> over winter break, and am testing on spare machines first.
>
> I have two identically configured computers, each with a 10 GB 
> partition, /dev/hda2. I intend to combine these two LAN/RAID1 style to 
> represent 10 GB of redundant cluster storage, so that if either machine 
> fails, computing can resume with reasonable efficiency. 
>
> These machines are called "cluster1" and "cluster2", and are currently on a 
> local Gb LAN. They are running CentOS 4.4 (recompile of RHEL 4.4) I've set up 
> SSH RSA keys so that I can ssh directly from either to the other without 
> passwords, though I use a non-standard port, defined in ssh_config and 
> sshd_config. 
>
> I've installed the RPMs without incident. I've set up a cluster called "ocfs2" 
> with nodes "cluster1" and "cluster2", with the corresponding LAN IP 
> addresses. I've confirmed that configuration changes populate to cluster2 
> when I push the appropriate button in the X11 ocfs2console on cluster1. I've 
> checked the firewall(s) to allow inbound TCP to port 7777 connections on both 
> machines, and verified this with nmap. I've also tried turning off iptables 
> completely. On cluster1, I've formatted and mounted partition "oracle" 
> to /meda/cluster using the ocfs2console and I can r/w to this partition with 
> other applications. There's about a 5-second delay when mounting/unmounting, 
> and the FAQ reflects that this is normal. SELinux is completely off. 
>
> Questions: 
>
> 1) How do I get this "oracle" partition to show/mount on host cluster2, and 
> subsequent systems added to the cluster? Should I be expecting a /dev/* block 
> device to mount, or is there some other program I should be using, similar to 
> smbmount? 
> 
As the previous post states, you need a shared storage. A quick and easy 
way to do this is to install iscsi-target on another system (target1) 
and then use open-iscsi to log into the target you just created. So 
have a third system that create the shared target. Then on cluster1 log 
into the target to create the ocfs2 cluster FS. At this point, you can 
mount this target on cluster1. On cluster2, log into the target and 
mount as you would normally. Of course you will need the correct cluster 
set up. Now you have two systems mounting the shared storage and both r/w.

Note: You may be able to do this with just two systems. Use cluster1 as 
the iscsi target system and ocfs2. On cluster1 install iscsi-target 
software and log into the volume share from cluster1 itself. Cluster2 
would just log in to the the target as normal.

> 2) How do I get this /dev/hda2 (aka "oracle") on cluster1 to combine (RAID1 
> style) with /dev/hda2 on cluster2, so that if either host goes down I still 
> have a complete FS to work from? Am I mis-understanding the abilities and 
> intentions of OCFS2? Do I need to do something with NBD, GNBD, ENDB, or 
> similar? If so, what's the "recommended" approach? 
>
> 
Yes you are misunderstanding how ocfs2 works. To use raid for the 
described purposes, you must use it on the target1 system mentioned 
above. On target1, raid two drives or two partitions and then use this 
array as the target volume you export to cluster1 and cluster2. This way 
you have a raid array for data protection and ocfs2 for service integrity.
> Thanks,
>
> -Ben 
>
> 


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