ReadyNAS 102 Single Drive Cold Backup

If you power down the NAS before you swap drives, then the system will boot up cleanly after the swap.

The operating system and all the system configuration is stored on the disks - so any settings you change on Disk A will need to be made again on Disk B.

When you update the firmware, the install package is also saved in the NAS flash memory.  When the system boots, it checks the flash version against the OS on the disks.  If the flash is newer, it applies the update to the OS on the disks.  If the OS is newer, it updates its flash from the OS.  So if you upgrade the firmware on the Disk A, then when you swap to Disk B the same upgrade will automatically be applied to Disk B.

SATA mechanical specs on insertion/removal are 50 cycles for internal cabled application; 500 cycles for backplane/blindmate application (per table 4.3 here http://www.calgreg.com/circuit-assembly/sata-specification.pdf ).  The 500 cycle spec should apply to the NAS backplane, but I haven't seen a clear answer on which spec applies to the connector on the drive itelf.  Though it would cost more, you could simply use two NAS for this, and swap the entire NAS (the 2-bay units are small enough to make that practical).

Note the RN102 is no longer manufactured, the currently produced entry-level unit is the RN212.  Any RN100 series you find for sale would be older inventory.  Netgear's hardware warranty is not transferrable, and they will not provide paid support on used units.