Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
Hi, you can work around the issue with the persistent-net-udev-rules by just deactivating these persistency rules... But your setup is rather complicated and error-prone compared to a real failover-cluster with heartbeat/corosync. And syncing root-images with rsync will give you a state from while its running. At worst this won't boot correctly at all. Whereas with a failover-cluster you get a running system with almost no interruption and no sysadmin interaction. Have fun, Arnold On Sunday 17 July 2011 21:09:16 Ian! D. Allen wrote: > Is this dual-ROOT scheme below workable? > > Let me explain using Machine A and Machine B: > > Machine A > - has a stock, ext4, bootable ROOT file system, non-DRBD > - has a second ROOT partition that is an RSYNC copy of Machine B > - has an ext4 data-only partition, DRBD primary, that uses > Machine B as DRBD secondary > > Machine B > - has a stock, ext4, bootable ROOT file system, non-DRBD > - has a second ROOT partition that is an RSYNC copy of Machine A > - has a (hidden) data-only partition that is DRBD secondary, with > Machine A as DRBD primary. (Hidden, because you can only mount ext4 > on one machine, not two.) > > Machine A does an RSYNC of its ROOT partition to the corresponding spare > ROOT partition on Machine B regularly, and vice-versa. > > When Machine A fails, reboot the Machine B hardware (DRBD secondary) using > the RSYNC copy of Machine A's ROOT partition. This brings the machine > up solo as if it were Machine A, accessing the local DRBD partition as > if it were Machine A (DRBD primary). (Perhaps some fsck will be needed > to make the ext4 on the DRBD usable?) Is this doable? (I know it works, > since I've tried it, but I'm wondering if I'm missing anything.) > > Work continues using Machine B's hardware, booted to be Machine A > (DRBD primary). This is now the new Machine A (DRBD primary), running > without any Machine B (DRBD secondary). > > Repair the failed old Machine A. Boot the old Machine A hardware using > the copy of Machine B's ROOT partition. This brings the machine up > as if it were Machine B, partnering with the new Machine A to provide > secondary DRBD for the data-only partition. This is now the new Machine B > (DRBD secondary). > > It it okay to bring up Machine B's secondary DRBD as primary, simply by > using the copy of the ROOT from Machine A? It it okay to make Machine > A behave as Machine B, simply by using a copy of Machine B's ROOT? > > One "gotcha" I've found is that booting Machine A's ROOT on Machine > B's hardware leads to mis-numbering of the Machine B network > cards as eth2 and eth3 due to Machine A entries already existing in > /etc/udev/rules.d/70-persistent-net.rules. I'll have to tweak those at > boot time, or perhaps I can create a merged file that works correctly > on both machines. -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 198 bytes Desc: This is a digitally signed message part. URL: <http://lists.linbit.com/pipermail/drbd-user/attachments/20110717/da28e3ee/attachment.pgp>