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Is there anyway to replicate a live (running) iSCSI LUN from one NAS to another using QNAP?

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Which NAS is hosting this LUN? – Hyppy May 24 '11 at 20:12
The first NAS (Which in my case is a QNAP, which provides the data for 8-9 VM's that we use as various servers). – Aaron May 24 '11 at 20:14
up vote 4 down vote accepted

Unfortunately, QNAP does not currently provide any facility for replicating iSCSI LUNs online.

If you want to do it offline, here's a handly little guide for offline iSCSI replication using QNAP: Replicate iSCSI LUNs

Your best bet may be to backup/copy the files on the client side of the LUN.

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Well what I was wondering is if it's possible to just mirror the first QNAP to another using some third-party software (drbd, rsync, ghettoVBC, etc.) – Aaron May 24 '11 at 20:25
dd will blindly copy one LUN to another; it will not insure data integrity. – Chris S May 24 '11 at 20:28
Even when the LUN is in use? – Aaron May 24 '11 at 20:39
@Aaron That's the problem. dd won't be able to tell if the blocks it is copying belong to a file that has been updated mid-stream. – Hyppy May 24 '11 at 20:44
It does not matter if it is in use. But if data blocks are changed after dd has read them but not yet completed the entire copy, it will not re-read and change them at the destination - you will end up with inconsistent data unless you can ensure that the LUN contents do not change during the copy process (which is basically taking it offline as you have no snapshotting functionality). – the-wabbit May 24 '11 at 20:44

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