Hi Steven I don't think Windows can mount NTFS read-only. You need to either break the mirror or FlexClone the dest vol. If using QSM, a LUN clone might work, but I haven't tried it.

If you FlexClone, you should create a separate snapshot on the source to use as the baseline. If you use one of the SnapMirror snapshots, it could break SnapMirror (or so I've seen - others have said it depends on which SM snap you use). With vol SM, the dest is read-only which is why you put the snap on the source and let it replicate over.

Share and Enjoy! Peter

... Sent from one of those phone+email doohicky things... I reserve the right to be wrong.

-----Original Message----- From: Stephen C. Losen [mailto:scl@sasha.acc.virginia.edu] Sent: Friday, July 27, 2007 06:42 AM Pacific Standard Time To: toasters@mathworks.com Subject: Accessing snapmirrored (read only) LUN from Windows?

We are working on a project that is housed in two separate buildings for disaster recovery.

In each building we have a Windows server, a FAS270 filer and a FC SAN switch.

The switches are not directly connected to each other, but we have long fibre runs so that each Windows server is connected to both switches. Each filer is connected to just its local FC switch. (This is a limitation of the FAS270, which has only one FC SAN port.)

One filer is primary and the other is backup. On the primary filer I have a large volume containing a large LUN and this volume is being snapmirrored (synchronous) to the backup filer over ethernet.

Both Windows servers can "see" both LUNs. We are using Windows clustering so that if the primary Windows server fails, the backup server will take over, using the primary LUN. If the primary netapp (or switch) fails, then we will need to manually intervene to cut over to the backup filer and LUN.

So here is my question (at last). Is it possible to access both the primary LUN and the read only backup LUN on a Windows server? Windows seems to be confused by the read only LUN and I am seeing errors on the backup filer saying that Windows is trying to write to the LUN. I'm not a Windows guy, but is there any way to look at the files on the read only LUN from Windows?

This isn't necessary for normal operations, I'm just curious.

Steve Losen scl@virginia.edu phone: 434-924-0640

University of Virginia ITC Unix Support