Swap drives from ReadyNAS Duo V1 to ReadyNAS 102

No. The RN102 uses a completely different file system, so migrating the drives won't work.

There's an easier way, though it ends up with the 2 TB drives in the newer NAS.
1) Buy 2x 2TB drives.
2) put both drives in the RN102, and set it up
3) delete unwanted default shares, and create a media share
4) Create and execute a backup job on the RN102 to copy the media share
5) Delete the "media" share from the Duo V1

I'd probably go for 3 TB drives, as they are running only $25 over the 2 TB models at the moment. They won't run in the v1 though. A NAS drive like the WDC Red is recommended.

Unfortunately I want the 2TB drives in the old NAS.

Anyway, I've thought of an even easier way:
1) Buy 2x 2TB drives.
2) Put one 2TB drive in the DuoV1 and allow it to become redundant.
3) Put the other 2TB drive in the Duo V1 and allow that to become redundant.
4) Put both 1TB drives in the new 102 and allow them to be reformatted.
5) Create a new "data" share on the new 102.
6) Copy the "data" share from the Duo V1 to the new 102.
7) Delete the "data" share from the Duo V1

That of course will work. You likely will need to reboot after step 3 to get the duo to expand. The RAID array is vulnerable during steps 1-3, so a backup is a good idea.

How old is the duo? If the firmware is down-rev you might want to upgrade it first. Also, if you don't have 4K disk alignment now, you should consider doing a factory reset (http://www.rnasguide.com/2011/06/22/why ... -readynas/)

A more complicated procedure could work for that - basically start with a 2 TB drive in the RN102, and copy all your data to that. Then remove both drives on the duo, and install the second 2 TB drive there. Back-copy the data onto the duo, and then hot-insert the 2 TB from RN102. After it resyncs, then install the old drives in the RN102 and do a factory reset.

One benefit of the more complicated procedure is that your old disks remain intact until the very end - giving a fallback if something fails (power down the NAS, restore the 2x1TB drives in their original slots, and reboot).

The Duo is old, but the firmware is up to date apart from the revision that broke PHP5, which I need to run my home grown CCTV setup. I haven't done a factory reset on it since the day I set it up, so it looks like I'll have to add that to the jobs list. I wasn't originally planning to, but it would make sense to move my CCTV onto the 102, possibly as a stepping stone to movinf to ReadyNAS

Looking at your proposed procedure I couldn't see where you could fit in a factory reset on the Duo?

I think what I'm going to do it this:

1) Copy both the data and media shares to my local PC (which just happens to have a nearly empty 1TB disk in it).
2) Put one 2TB drive in the Duo and allow it to become redundant.
3) Put the other 2TB drive in the Duo and allow that to become redundant.
4) Put both 1TB drives in the new 102, reset and allow them to be reformatted.
5) Re create both shares on the 102 and copy the all the data back from the Duo.

Now I will have two NAS with identical copies of the same data, plus the snapshot on my local hard disk.

6) Work with the 102 as the "live data" storage and verify the transfer was successful.
7) Get PHP5 and my extras installed and working on the 102
8 ) Update the firmware and factory reset the Duo
9) Re-create the media share on the Duo
10) Copy the media share from the 102 to the Duo.
11) Verify the media share transfer is OK and delete the copy from the 102.
12) When I'm absolutely happy with everything, delete the backup from the local PC.

If you are going to reset the duo in step 8 anyway, there is no point to steps 2 and 3.

I didn't fancy having only one copy of the data though. If I do steps 2 and 3 I will have a RAIDed backup AND the copy on my local machine right up until I decide to reset the Duo. There's likely to be several days while I get the 102 configured how I want it and move my CCTV stuff over.

By the way, for the 102, do I need PHP for the ARM processor?