On Thu, Mar 28, 2013 at 5:43 PM, Daniel Parthey < daniel.part...@informatik.tu-chemnitz.de> wrote:
> Michael wrote: > > short version: Is there any 3 host (two MX and one frontend IMAP) that > > can use a shared (iSCSI) ext4 volume? > > No. iSCSI exports a block device from one host to another single host. > > No, you can export iSCSI to multiple host. > > Long version: > > I am running a very complex setup right now with two MX, two > > proxies(lmtp/imap)/imap-frontends and two backends mounting an > > ocfs2 volume. > > > > I would like to reduce the complexity (and the number of hosts) and > > get rid of ocfs2. I ask myself if I can use an ext4 iSCSI-LUN using > > this setup: > > > > MX01 -> lmtp:unix:private/dovecot-lmtp -> mail_home: /var/mail > > MX02 -> lmtp:unix:private/dovecot-lmtp -> mail_home: /var/mail > > IMAP01 (imap) -> mail_home: /var/mail > > You cannot mount an iSCSI device simultaneously from different hosts > without using any locking/cluster filesystems. Otherwise you would > risk corrupting your ext4 filesystem. > > Use NFSv4, DRBD or any other clustering mechanisms to provide > high availability while preserving data integrity. > > Regards > Daniel > -- > https://plus.google.com/103021802792276734820 > Problem is ext4, It is not a cluster file system, as far as I know. So, it does not coordinate file locking, across multiple nodes. It would result corruptions. You could get it down to 2 nodes, with drbd and any non cluster file system. Since only one node, that does the I/O. Any file system would work. I like xfs better than ext4. mx01 -> lmtp: tcp (vip) / (dovecot imap) -> mail_home mx02 / Google for "mysql drbd pacemaker". The configs are similar. Kui.Z
