RAID 1 with 3-drive offsite rotation of Time Machine backups

[The DataDude]

I have been using the following scheme for the past two years with another vendor's RAID 1 device directly attached to one of my computers and shared over the network:

-- 2-Drive RAID 1 array with a 1TB drive in slot 1 (HD1) and and 1TB drive in slot 2 (HD2), and a third 1TB drive kept offsite (HD3).
-- Drive partitioned into two partitions and Time Machine configured to do a SparseBundle backup for each of the two machines on the network.
-- On a weekly basis, the following rotation scheme is used:
Step 1: After one week: rotate HD1 to an offsite location. Move HD2 to slot 1 in the NAS. Add HD3 to slot2 in the NAS.
Step 2: After one week: rotate HD2 to an offsite location. Move HD3 to slot 1 in the NAS. Add HD1 to slot2 in the NAS.
Step 3: After one week: rotate HD3 to an offsite location. Move HD1 to slot 1 in the NAS. Add HD2 to slot2 in the NAS.
-- Repeat the above on an ongoing basis

Apparently this plan requires that the RAID firmware can handle drives moving from slot-to-slot and also has the capacity to automatically re-mirror a new drive brought in to the array from offsite.

I am looking for a NAS solution to replicate the above so that the backup can be on the network and not depend on its physical attachment to a Mac on the network.

So, two questions:
1. Will your ReadyNAS products work with the above scheme?
2. Which product would be best?

Thanks!

Eric

[mdgm]

No. That procedure is asking for trouble. RAID-1 provides redundancy. If you follow the procedure you suggest you are asking for data loss regardless of the vendor you use. See http://www.ReadyNAS.com/?p=3153

I'd suggest a Ultra 2 backed up to USB disks rotated offsite.

[CharlesLaCour]

From the posts I have seen many people have tried or were planning to try this kind of off site backup. This is not a good idea. RAID is not a technology that was designed for repeated "failure" of drives in this manner. You will force a a volume resynchronization with each drive swap increasing the IO load on the drives decreasing their lifespan and increase the possibility of volume corruption/failure.

Also hot swappable drives even though they are designed to be removed and replaced the mechanisms are not designed to continual wear and tear of doing this and can cause the SATA connections to become flaky and eventually to fail.

There is no enterprise class NAS that I know of that recommends or even supports this "backup" scenario. If there are any consumer grade NAS that "support" this I would love to see how they overcome the issues above.

[mdgm]

Then there's the risk of damaging the disk due to ESD through handling it bare which becomes quite significant if you handle it bare regularly. Every time you handle the drive bare you risk damaging the drive.

See some good posts by the General: http://www.readynas.com/forum/viewtopic.php?f=25&t=27855&p=154032#p154032
http://www.readynas.com/forum/viewtopic.php?f=65&t=26952&p=148849#p148849
http://www.readynas.com/forum/viewtopic.php?p=272981#p272981