Rainer, Although I can't help you with the specifics of LVM, I can tell you that this is a common config for many companies. Many people use RAID5 in the disk array because it is efficient, and offloads the parity calculations from your server. Using host based RAID 1 will protect your application if any of the disk arrays crash/fail. Multi-pathing will protect against HBA failures as well as some switch or disk array port failures. I would recommend keeping the SAN switches in two separate fabrics if possible, eliminating a single point of failure in the FC switch mgmt software (namespace?). If you ever want to take a look at a LVM alternative, the VERITAS Volume Manager included in our Foundation Suite (we have a File System in there as well) is very robust in these types of environments. More info at www.veritas.com/linux. Regards, -Brian -----Original Message----- From: Rainer Krienke [mailto:krienke@uni-koblenz.de] Sent: Friday, May 30, 2003 2:10 AM To: linux-lvm@sistina.com Subject: lvm in linux SAN enviroment ? Hello I recently posted about a problem with lvm (subject: Strange lvm on raid1 on top of multipath problem posted on 05/29/2003). Well in between I could image what the reason might be but I'm quite unsure if my theory is correct: There are three machines and three hardware raid 5 devices connected by two fibrechannel switches to each other, so each host can see each physical partiton on each of the three disk devices. Now on each host I configured *one* md-raid1 device of cource based on different physical disks. There is one more layer of abstraction because the raid1 device is actually built upon a multipath md-device which uses different paths to the physical disks. This works just fine Next I defined *one* physical volume on each of the three hosts on the md raid1 device and then defined a volumegroup consisting of one physical volume on each of the hosts. Finally I created several logical volumes. So on each host there is exactly one raid1 device used as physical lvm volume and one volumegroup with several volumes defined. The question is if such a setup can work or is it bound to fail? Each host can because of the san network see each existings *physical* disk which might be a problem for vgscan, but on the other hand I created the *physical volumes on raid1 md devices* and these devices are different on each host and each host has exactly one such md device defined (it cannot "see" the other md devices on the other hosts allthough it can see the underlying physical partitions). Can anyone please comment on this scenario? If this setup is simply "wrong", how could I tell vgscan which might to my knowledge be the problem, that it should not scan all physical devices it finds to avoid trouble. Thanks in advance Rainer -- --------------------------------------------------------------------------- Rainer Krienke, Universitaet Koblenz, Rechenzentrum Universitaetsstrasse 1, 56070 Koblenz, Tel: +49 261287 -1312, Fax: -1001312 Mail: krienke@uni-koblenz.de, Web: http://www.uni-koblenz.de/~krienke Get my public PGP key: http://www.uni-koblenz.de/~krienke/mypgp.html --------------------------------------------------------------------------- _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/ _______________________________________________ linux-lvm mailing list linux-lvm@sistina.com http://lists.sistina.com/mailman/listinfo/linux-lvm read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
