Making file system available to mutiple servers

[Trojan36]

I am using HP-UX servers and EVA8000 SAN.
If I have one lun of 10TB, how can I make this LUN/filesystem visible (read/write) from two or more servers. I will handle file locking in application so no need to worry about that. I just want to be able to see the same filesystem via the SAN switch in Active/Active mode. Does SecurePath sw help with this? Thx in advance.

[A. Clay Stephenson]

It ain't gonna happen. The problem (and I don't care about your file locking) is buffer-cache consistancy across all the boxes. ServerA won't have a clue about ServerB's buffer cache and absolute chaos is assurred. You can mount the filesystem read-only on all server; you can mount it read-write on one server; export it; and all other hosts access it via NFS.

You can access the LVOL's in read-write mode if using raw i/o but then the application is solely responsible for locking and contention.

Finally, if all the boxes are running 11.23, you can look at the Clustered Filesystem (CFS). It does exactly what you want.

[Ken Grabowski]

Of course Clay has some very good points, but there are packages that are designed to deal with multiple presentations of disk to HP-UX. MC-ServiceGuard is a good example of one. But you should proceed with great fear when you decide to do something like this on your own.

Your EVA will allow you to present the same vdisk to multiple servers. Simply go into EVA Command View. Select the vdisk in question, and go to the presentation tab, and select the host and lun you want to present to.

But before doing so, I would spend some time with an HP support engineer to determine how and if you really want to go down this road.

[A. Clay Stephenson]

With or without MC/SG, mounting a common filesystem read-write on multiple hosts is guaranteed disaster. The ONLY exception to this is CFS and it uses a dedicated network for the filesystem related traffic. CFS makes the filesystem look like a plain vxfs filesystem on every host.

This has nothing to do with the hardware the filesystem happens to be housed on and everything to do with HP-UX itself.

[Torsten.]

If you have access to the file system and you are using lvm you can activate the VG in read-only mode and mount the file system in this mode only. File locking is by choice in unix, as you know. The software can ignore it without problems. It's not a question of secure path. Take care of your data!