Oops, yes you are correct. Cheers Paul
> -----Original Message----- > From: Sunil Mushran [mailto:[EMAIL PROTECTED] > Sent: 19 October 2007 17:31 > To: paul fretter (TOC) > Cc: Randy Ramsdell; [email protected] > Subject: Re: [Ocfs2-users] Missing something basic... > > Actually GFS(2) is also a shared disk clustered filesystem. > > Lustre is a good example of a distributed fs. > > paul fretter (TOC) wrote: > > I had similar confusion myself when first looking for a suitable > cluster > > FS. I'm not an expert at this, so forgive me if my language appears > > simplistic. > > > > There seemed to be 2 basic species: > > - There are those which aggregate local storage LUNs from each host > into > > a single contiguous 'virtual' device, e.g. RedHat GFS etc. Bear in > mind > > the4se 'local' LUNS could be a local disk, or a dedicated LUN on a > SAN. > > > > - Then there are those which expect all hosts to have direct (shared) > > access to the same LUN. > > > > OCFS2 falls into the latter category. > > > > For disk redundancy you could use a shared disk shelf (e.g. IBM > DS4xxx), > > create a RAID(1,4 or 5) set in the hardware and present it as a > single > > shared-access LUN. All your nodes then have a connection to the LUN > > (e.g. by fibrechannel). In effect it is a small SAN! OCFS2 is then > the > > glue which manages the file locking and metadata so that nodes don't > try > > to write to the same blocks at the same time. > > > > By creating a "RAID" using multiple OCFS2 volumes you are bringing > the > > role of device level redundancy work into the OS, which is > effectively > > software RAID and is not conducive to high performance or > reliability. > > > > Then for high availability of the storage, a good way might be to > create > > a duplicate shared device and let the hardware perform mirroring for > you > > (e.g. over fibrechannel, infiniband, iSCSI) etc, and also let the > > hardware do the failover for you. > > > > So, by using a SAN with hardware RAID and hardware mirroring to a > second > > SAN device (with hardware RAID), you can achieve resilience and high > > availability, leaving OCFS2 blissfully unaware. > > > > Hope this helps. > > > > Kind regards > > Paul Fretter > > > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] [mailto:ocfs2-users- > >> [EMAIL PROTECTED] On Behalf Of Randy Ramsdell > >> Sent: 18 October 2007 14:00 > >> Cc: [email protected] > >> Subject: Re: [Ocfs2-users] Missing something basic... > >> > >> 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 > >>> > >>> > >>> > >> _______________________________________________ > >> Ocfs2-users mailing list > >> [email protected] > >> http://oss.oracle.com/mailman/listinfo/ocfs2-users > >> > > > > _______________________________________________ > > Ocfs2-users mailing list > > [email protected] > > http://oss.oracle.com/mailman/listinfo/ocfs2-users > > _______________________________________________ Ocfs2-users mailing list [email protected] http://oss.oracle.com/mailman/listinfo/ocfs2-users
