Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Thu, Jul 07, 2016 at 12:01:47PM -0400, James Ault wrote: > I see the Manual Failover section of the DRBD 8.4.x manual, and I see that > it requires that the file system be umounted before attempting to promote > and mount the file system on the secondary. > > What I meant by "those status flags" in my first message is that when a > node mounts a file system, that file system is marked as mounted somewhere > on that device. The "mounted" status flag is what I'm trying to describe, > and I'm not sure if I have the correct name for it. > > Does pacemaker or manual failover handle the case where a file server > experiences a hard failure where the umount operation is impossible? > How can the secondary copy of the file system be mounted if the umount > operation never occurred and cannot occur on server1? Forget about replication and failover for a second. Hard crash a node with a mounted file system. So it is "marked" as "mounted" "somewhere on that device". Right. You can never mount anything again after a hard reset. That does not make any sense. So any *failover* would basically look like a hard reset, and would need to do every "crash recovery step" that a classic single node setup would do after reboot. (A "clean switchover" would look like a "clean reboot", and no recovery steps are necessary.) For an ext2 or similar file system, that means you need to fsck. For a journaling file system like ext3, ext4, xfs, etc., that means it will do journal replay on mount. With "multi mount protection" or similar enabled, after a failover, you have to do just the same you need to do after a hard-reset of a classic single node setup. Which is basically: just wait for the "mmp" magic to determine that the device is currently dirty, but unused. There is no other "special magic" done by the drbd and Filesystem resource agents of pacemaker, either. "works for me" (and apparently everybody else, too). If it does not for you, then apparently something is "special" in your setup. -- : Lars Ellenberg : LINBIT | Keeping the Digital World Running : DRBD -- Heartbeat -- Corosync -- Pacemaker DRBD® and LINBIT® are registered trademarks of LINBIT __ please don't Cc me, but send to list -- I'm subscribed