Copy from NAS HD to new HD

It is possible, but there are risks.  Because of those risks, you'll want to insure you have a full backup of your data first (which kinda eliminates the benefits of doing it).

It becomes a bigger problem if you have apps installed.  I don't recommend you do it if you do, unless you can un-install them and re-install afterward.

But the process is this:

1. Make sure you are in FlexRAID.  Special note: If your NAS decides you have "expanded volumes" (which I think means multiple RAID groups), you will be prevented from going back to XRAID later.
2. Add the new drives, format them, and create a new volume.
3. Copy the necessary files.  Backup jobs are still the best here.
4. Power down and move the new drives to the new machine.  Do not "EXPORT" the volume, doing so will make it not work as a primary volume on the new machine.
5. Power up each.  On each, you will see it complain that there is a missing volume.  DESTROY that missing volume.
6. Both will also have the same network ID, so change that.  If you use a static IP, you'll have to power up just one and change that first so they don't conflict.
7. You can also now try to go to XRAID if you want that, but it might refuse.
8. Now, here's the risk:  On both machines, your original volume was marked as the main one, so it contained your home and apps folders.  But you destroyed that on the new machine.  The OS is supposed to create new ones (that will be unpopulated), but I've seen that fail.  It's fixable via SSH, but not simple.
9. If you need user folders, the users will have to log in to the new machine for them to be created or you can use mkhomedir_helper via SSH to create them.
10. Note that the GUID for both machines will be the same.  I'm not aware of that causing any problems, but I may simply have not come upon them.

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makkistyle wrote:

 

transfer over network will take too much time .. 

 

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I've copied 12 TB in a day or so, and it is the safest and easiest way.  If something goes wrong, you could end up needing to restore 20 TB of data on the main NAS.  Note the backup jobs are NAS->NAS, so they don't tie up a PC.

If I were inclined to try your approach, I would do something like:

1. Install a spare disk on the new NAS, update the software as desired, and change to FlexRAID.  Create any user accounts that you want on the new NAS.  This disk will be removed later.
2. Insert the two new disks into the existing NAS, and create a second data volume on them.
3. Run the disk test on that new volume (which will take a while, given the size).
4. Create temporary share names to receive the files.  The share names have to be different from the ones in the existing volume.
5. Create and run a backup job for each share to copy the data from each share to the matching share on the new volume.
6. If you use home shares, create a temporary share for home, and similarly create/run a backup job for it.
7. After all the data is copied, export the new volume from the volume page.
8. Power down both NAS, and move the new disks to the new NAS.  Then power up.
9. The volume should appear on the new NAS.  The OS partition on the disks will be resynced from the spare disk (from step 1).
10. Destroy the volume from the first spare disk.  Power down, remove the spare disk, and reboot.
11. If you want to match the share names on the first NAS, then rename the temporary shares.
12. Log into each account on the new NAS from a PC, which will create the home account for that user.  Then copy the data from the temporary home folder to the real home folder.  When finished, delete the temporary home share from step 6. 

Sandshark might also have a suggestion on how best to do what you are asking.

EDIT- just saw Sandshark's version.  FWIW, I started with a scratch disk in the new NAS to avoid the export problem he mentions.