Re-Syncing After Hdd Disaster Recovery /cloning


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Hello Sync-ers,


In my computer setup, I have integrated a disaster recovery system by cloning (or "ghosting") entire physical drives in the case of hardware failure. I have BTsync running between my desktop and laptop, cloning one of the physical drives in question. My query is in regard to BTsync's behavior when swapping out a drive or "rolling back" the data on a partition on one machine. What happens to the data on the other after re-syncronization?


For example:


Let's say I have My Data Drive on My Desktop PC which contains Folder A.

I clone Data Drive to My Laptop PC. It now contains Folder A as well.

I set up a synced folder betweent he two machines via BTsync: as I work on Data Drive on My Desktop, it syncs Folder A to the Laptop and vice-versa.


During the next months, I create Folder B on My Desktop PC. Of course, it gets synced to the Laptop. Both PCs now contain Fodler A and Folder B.


That night (horror!) the Data Drive on my Desktop fails.


I need ZERO DOWNTIME so I swap out the physical drive on My Desktop PC for my clone drive I made months ago. This drive does not contain Folder B.


The computer boots, and I am ready to go: BTsync starts up - what happens?


   a) does Folder B get deleted from Laptop or

   B) Does Folder B get copied from Laptop to Desktop PC


Any clarification as to this process will help my sleep patterns greatly.




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Wouldn't a raid be infitintivly more usefull for this purpose?

With RAID, all the drives reside at the same physical location, so if there's a physical disaster there, you're screwed. My NAS has two 3TB HD's set up as RAID 1, but when the amount of risk I was running became clear to me, I set up a second, identical NAS, cloned the first to the second as the OP describes, and moved it. In other words, I synced about 2TB, then moved the second NAS to another location far away. I had to turn off sync for all but my most active 15GB of sync folders because it's not practical to sync 2TB where I am unless they're on the same LAN.


I've thought I could update the cloning by bringing the remote NAS back to the home LAN periodically and turning on sync for the 2TB portion. I'm too afraid to do that, though. I've reported sync glitches and data losses when rebooting Linux devices in other threads. I'm not confident in shutting a device down, moving it to the home LAN, and then syncing folders that haven't been in sync for several months. The 2TB sync would take a very long time, making it way too risky to end up having to track perhaps thousands of anomalies. I've thought I'm better off periodically bringing the second device back and re-cloning (syncing again from scratch). That kind of sucks, though, because not much of the 2TB actually changes (but too much to keep track of manually). And since cloning risks putting all my stuff in one physical location, I now want to find a third location and perhaps clone on a rotating basis. If anyone has a better idea to keep data reasonably safe using BTS exclusively, please post.

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But for uptime BTSync would be terrible. And you certanly won't get ZERO downtime. Raid can protect you against hardware failure, with ZERO downtime as he asks for. ZFS for instance can be sent to another server too, for an offline backup identical to the first. If all drives dies, just plug in one from the backup location. Raid is a far better solution.

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