Sync files on 2 different ext drives

I have two large ext drives A: and B:.  A: stays with my computer, and I want to store B: off site.  

At this point the three drives are not synchronized and I want to make sure they are all the same.  I can't just copy A: to B: because, right now, there are mixed files on both drives.  

Is there a way to simply sync all the files so they match?
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JohnBusiness Consultant (Owner)Commented:
I use SyncBack Pro for that ( It is well suited to this task and I do this myself. I have one profile to sync back to my desktop and another profile to sync to my very large USB key. All devices are in sync.  I do use two profiles to keep things straight in my own mind, but it works well, reliably, and without error. ... Thinkpads_User
David Johnson, CD, MVPOwnerCommented:
there is the included with windows robocopy and sibersystems goodsync

when you say there are mixed files on both drives do you mean different versions of the same file? Please elaborate.
mikecox_Author Commented:
In some cases there are different versions of the same files and in some cases completely different files on both drives.  If possible I'd like to avoid having to install new software; but if I must...
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JohnBusiness Consultant (Owner)Commented:
You logically cannot sync 3 copies of a file with any tool because you cannot know which one is true.

I sync between computers (either system can change) and once synchronized, I then sync to the USB key. It is subservient. So you need to pick one hard drive as subservient, or be incredibly organized as to which of the 3 devices has the true copy.

SyncBack Pro is cheap, but it allows multiple profiles and further allows you to change the direction of sync if you know the location of the true copy.

... Thinkpads_User
mikecox_Author Commented:
My A: drive will be the "subservient" drive.  I back up everything to that drive, then copy that backup to my B: drive.  There are tow B: drives, one on site and one off site.  I just need to files on the B: drives to match the ones on my A: drive and, initially I will need so sync the B: drives because, right now, they contain some files that are not on the A: drive.
David Johnson, CD, MVPOwnerCommented:
any syncing software will use the last modified date to determine whether or not to overwrite the destination file in its overwrite options.

from drive a: > b
robocopy a: b: /e /xo
and the converse:
robocopy b: a: /xo

you can use robocopy a: b: /e /xo /L
this will just show you what files will be copied as a test
JohnBusiness Consultant (Owner)Commented:
>>> My A: drive will be the "subservient" drive.  

So then you are fairly well organized. Any sync tool should do.

I like and use SyncBack Pro because it uses a standard Windows interface, offers multiple profiles, groups profiles, and allows exclusions (in the case of licensing or control files). I use all these features.  There is a free version and a free trial of the paid version.

.... Thinkpads_User
mikecox_Author Commented:
How do I access Robocopy? I typed it into the search field and something popped and then disappeared in a flash.
David Johnson, CD, MVPOwnerCommented:
it is a command line program
start cmd then type robocopy in the command window
@name this whatever i.e. copyit.bat
@echo off
@echo this will copy from %1 to %2
@echo press ctrl-c to stop
robocopy %1 %2 /e /xo

Open in new window

If you want to try a free GUI program, look at TreeComp... it's fairly small (its setup file's a little over 1 MB), and fast.
e.g. I just ran it against some files and their backups, both on network drives, and it took less than 3 minutes (160 seconds) to compare 137 GB in 37,423 MP3 files (7,873 folders) on each drive.

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mikecox_Author Commented:
Syncback  was ok but cost, Robo was command line; too much of a hassle, Bobocopy was small and free.
JohnBusiness Consultant (Owner)Commented:
Thank you, and I was pleased to assist. There is a free version of SyncBack if you wish to go that route. ... Thinkpads_User
mikecox_Author Commented:
I'm sorry, I thought is wasn't free, otherwise I might have awarded more points to you.  And it wasn't Robocopy that was free it was Treecomp. If that doesn't work out I'll try SnynBack.
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