External HDD mirroring using USB Interface

That is actually a classic backup solution using time machine, where both boot drive as well as EHD is being backed up incrementally in a format which is native to OS Mavericks. Such a backup can only be used to "Restore" the files back onto the source machine. Excellent for normal backup operations.

However, what I have in mind is two sets of EHDs (external HDD) formatted to FAT or maybe the NTFS, where the files are kept in a standard format and can be read on ANY machine whether OS X or Windows.

On a proper mirrored system, both HDDs appear to be one only, and the filesystem also appear to be one. So when we handle a file from the mirrored system, the cloning on the two HDD is done transparently without the user getting to know of it. Failure of one HDD will not result in loss of data since that would be available on the other HDD, and when the faulty HDD is replaced, the data gets replicated again from the good HDD. Such a mirrored system is very expensive and not affordable by ordinary mortals like most of us.

So, to get around the expense part of the whole thing, now that we have fast USB3 interfaces, we can possible use 2 x cheap EHDs hooked onto two separate USB 3 ports, and use them as a mirrored set. It is understandable that since the computer cannot access two USB ports simultaneously, there will be some trade-off to the speed of handling the two EHDs, but, that is acceptable. At least we have two identical sets of data available, which can be used in an emergency on any other system. Should one EHD crash, we can always extract all data from the second one.

I am not sure if such an arrangement is possible using the existing functionality of the OS X, and so someone may need to whip up an app or a script for doing this. Alternately, some really clever geek could come up with some remarkable solution/work-around. Looking forward for some bright spark from somewhere.

For all who are interested in this subject.......

I have finally found an excellent solution written by Christopher Phin and can be found here..

http://www.macworld.com/article/2950478/storage/how-to-configure-a-cheap-secure- raid-backup-system.html#tk.nl_mwbest

I have tried this out and works just as I had desired vide my question in this discussion given above.

Thanks Christopher !

I am currently on Yosemite and not sure if this will work in earlier versions.

You are right Allan, But...

My requirement was for a simple, inexpensive and a practical way for duplicating two disks simultaneously with whatever data I need to put on one so that I always have an exact duplicate on the other. Should one disk crash, I will have something to fall back on. My old HDDs of yesteryears can thus be put to some good use. With a proper FAT format, it can also be read in windows and other OSs as well.

For my regular current work related backup, well, I have the time machine backups on one of the latest USB 3/ nTB disks.

I agree to your viewpoint.

However, there was also a desire to use all electronic equipment to its last breadth. It gives me a personal satisfaction to help the green initiatives.

Also, my requirements was necessitated due to very specific reasons, and since I do have existing older HDDs in perfect working condition it was only natural to find use for them. Incidentally, my work also requires me to work on multiple platforms.

Finally, it is always fun to explore, try and learn to do something new and different. It gives a lot of personal satisfaction.