Eg - have two addresses A and B. Each has a NAS. A and B are linked by the internet, although the link is not amazingly speedy hence the two NAS.each end also has a WIFI router. Whichever address I am at, I can access the data with wifi from the local NAS on my laptop, and any changes are propagated to the other NAS. Propogation could happen at a fixed time of day as a backup job, rather than in real time. Each end may also have a fixed PC.
It is possible. I have not done it, so I am not an expert, but I believe replicate can be used for this. I will leave to others who have experience with it to state how it is to be done.
it is possible to mirror data from one nas to another via backup jobs, but not 2 way replication*.
@ papabear, the replicate service is only 1 way, it does not perform 2 way mirroring.
*the egnyte service has something that may work for you, but it isn't free, its a paid monthly service.
If the data set you need to replicate is small, you might be able to get away with setting up dropbox addon on both nas, it should replicate via dropbox but obviously you will be limited to whatever size dropbox account you have.
It's unlikely that the same file will be altered on both systems before the next "backup" takes place
What happens if I alter a copy on share2 and the next "backup" job is share1-> share2? Will the new changes on share2 be overwritten with the old copy from share1?
downsides: (a) file and folder deletions are not possible, as the next inbound rsync will just restore the deleted files. (b) if a file were modified on both systems, you can't predict which one will win out (c) if the time is not synced on the two systems, you might get unpredictable results.
(d) The last step- "Schedule both these jobs so that they don't run at the same time" cannot be guaranteed. rsync over the WAN can take a long time. You'd need to be very conservative on the scheduling, which would make the sync time slow. Even then it is a hope.
Can you structure the folders so that the data created on each side is segregated? If each folder is only written at one location (but available for reading on both) then this is much simpler.
Great discussion. I have a duo v1, with a number of shares already created which made sense for me at the time (media, docs, personal, etc). My brother is looking at getting one also, and we're wanting to provide mutual offsite backups for each other. Obviously we are explicitly NOT intending to be updating each others files, so should be no sync issues. Does this seem feasible? I can see some challenges re naming standards to ensure they make sense 'at both ends'. Any advice? Cheers!
You could set up a brother-backup share on each site, and backup to folders within that.
Though with the duo v1 you won't be able to create a secure connection (since rsync over ssh isn't a duo v1 feature). You could possibly create a vpn tunnel between your two locations if you added in vpn routers. Or use viewtopic.php?f=47&t=29688 - which will be slow, but may be good enough.
Also, the initial backup would be faster if you put co-located the two NAS and did an NFS backup between them (then editing to rsync and running again).
Thanks StephenB Ah, so you can copy shares on one nas to sub folders on another? Just what I wanted. Yep, was intending to do initial backups locally somehow 🙂 Security was certainly a concern for us, so might make the leap to v2 at both ends rare than faff about with plugins and any other mismatches. Guess much of is is simple, but hard to 'play'' with with only one duo, and what seems obvious isn't always what manufacturers actually provide! Thanks for the input and reassurance!
Forgot to say, I've got a nice fast 10mb cable link, soon to be upgraded to 30. Unfortunately Bro is in the Styx, and has little more than wet string AdSL! He knows this is going to be the killer of this whole idea! One reason we've not yet forked out for the new nas yet! Cheers!
If you are prepared to upgrade to a new NAS, then installing CrashPlan on them is another way to go. That does require ssh access, and a NAS that supports java. There are guides for setting this up on the x86 and the v2 products. An x86 would get faster performance. BTW, if you are upgrading, you might consider a 4 slot unit.
The "family and friend" feature will let you back up to each other's NAS (which should be free), and for a reasonable price you can get a cloud backup on CrashPlan servers. Crashplan's cloud backup is continuous, the free backup is not (it runs daily)
The main drawback is that the backups are proprietary, so you can't read them without their application. Note that your brother also cannot read your files and vice versa, so if you are wanting to share stuff you'd do that separately. A second drawback is that although Crashplan provides some info on "headless" linux installations, they don't provide much support for that setup.
I've been using it for about a year now, so far it has worked out well. I have my entire NAS volume backed up in their cloud, and also use the "family and friend" feature to back up our family PC to my Pro.
