Storage node Drive sharing issue

If you have drive sharing, it means you share one physical driver.  Let's call it TAPE1.  You can zone this physical drive to numerous hosts and they become logical drives.  For example if you shared TAPE1 to xyz.com and abc.com you would have:

xyz.com:/dev/rmt/20stcbn

abc.com:/dev/rmt/21stcbn

This is the SAME drive shared by two nodes.  When you mount over application being aware of sharing a tape on one host you see following:

- request to load tape to xyz.com:/dev/rmt/20stcbn

- tape loads at physical level to TAPE1

- xyz.com:/dev/rmt/20stcbn has tape loaded and abc.com:/dev/rmt/21stcbn handles this as drive in use and won't try to access it until xyz.com is using it

This means that 2 different host cannot use same physical drive at the same time.  Period.  This is not the issue, but rather how the things have always worked.  The benefit of drive sharing is that each host bypasses network and can dump data directly over SAN.  This setup makes sense only if you have backup schedule such that you do not have overlapping for the same drive (even when it comes to restore that would be pain to manage).

So if you share the drive answer is - no, you can't use it at the same time if using same physical drive.  If using EDL, you do not need drive sharing as with EDL you can create as many drives you want and need thus avoid any traps by drive sharing in the first place.