"Bad message" with a new SAN using multipath and iSCSI

Solution 1:

That is normal behavior for a non-clustered file system.

To use iSCSI SAN with Ubuntu compute servers, a clustered file system should be used.

You should probably learn more about GPFS, GFS2, Lustre, GlusterFS, and OCFS2 and use one of them on top of iSCSI SAN.

Edit: Good description of what’s going on can be found here:

https://forums.starwindsoftware.com/viewtopic.php?f=5&t=1392

Solution 2:

ext is not a cluster-aware filesystem, so the moment a second node mounts it it will be corrupted. This is because there's no common block locking mechanism, which there is with a cluster-aware filesystem

Use a cluster-awre filesystem.

Solution 3:

Um...

A SAN is not NFS. Unless you're using a shared/cluster filesystem, you can't just mount something ext4 onto multiple hosts.