Windows 7: RAID or Mirror Across Computers?

Where to put the data ... hmm.  I had a home network with two computers running Windows 7.  If the data I needed to work with was on one computer and it went down or had one of those frequent Microsoft maintenance or service interruption needs, I couldn't get to it from the other computer.  But if I put the data on a server, then (a) I had to buy and maintain the server, cables, routers, etc., (b) I had slower access times, (c) the data would then be unavailable to *both* machines (unless I wanted to swap out one or more hard drives) if the server went down, and (d) I had found that, if I accidentally corrupted or deleted the wrong file, a server might not be willing to undelete it.  Not a big deal, assuming you had good backup, but there were painful exceptions.

So it occurred to me:  can you put the data on one computer, so that it can function as a standalone, and also put the data on the other computer, so that it is a standalone too, but then have a constant RAID or mirror arrangement between the computers, so that whatever you do with the data on one computer is immediately duplicated on the other computer?  That way, you've got local speed, no server, and redundancy during downtime on either machine.  Basically, two-way mirroring:  when a file is modified, it checks the other computer, and the two of them figure out which version is newer, and it overwrites the older version on the other machine as well.  All you need is a router, if that.

I figured possibly everybody else already knew the answer to this.  But since I didn't, I started with a search.  Only six hits.  It looked like the concept of "RAID between computers" was a nonstarter.  Alright, a different search.  Wow, "mirror between computers" produced 13 hits.  But, OK, not to complain, it seemed most of those hits were for TreeNetCopy.  Take it out of the equation, and the search produced only five hits.  So TreeNetCopy seemed to provide the path forward.  But it didn't look like CNET, PCMag, or other big-name sites had reviewed it.  I went to the product's home website and found out why:  it was for systems using Windows NT or Windows 2000.

Apparently mirror and RAID were not the concepts I wanted.  How about incremental backup?  You couldn't have it running constantly; it would have to finish one scan of the system's files before it could start on the next one.  So maybe you'd set it to run every 15 or 30 minutes, or however a scan would take to finish, across the network connection.  This wouldn't be nearly as good as software that would detect and propagate changes as soon as they were made, but I wasn't seeing how to find anything like that.  With a 15- or 30-minute delay, you couldn't have someone being able to open the file on computer B as soon as someone else updated it on computer A, unless possibly if you had a script that would somehow be able to run the incremental backup manually for a given folder by just maybe choosing a right-click context menu option.

Alright, a different approach.  I had been using Beyond Compare, a file comparison tool.  It still looked like one of the more capable file comparison tools, so how about using it?  As I was thinking about that possibility, I realized that I didn't like the idea of having to do a right-click or other manual update.  The computer could crash before I got around to that, and then I wouldn't have the current data in the parallel folder on the other computer, and therefore really couldn't just keep right on working where I left off.  I had only used Beyond Compare as a manual comparison tool, where I would start it up and it would run for a while and compare directories and then show me what needed to be mirrored to my backup drive, and then I would click the buttons necessary to do that.  I knew it was possible to write scripts to automate some of this, but it seemed unlikely that scripts would help Beyond Compare remain up-to-the-minute on all of the file changes made on the system.  Most likely, I could set up scripts to run in some frequently used folders, and maybe even to automate the mirroring of those folders, but other folders would be left out in the cold.  Possibly I could have multiple scripts doing comparisons of more- and less-frequently used folders on different schedules, so as to increase the likelihood that most folders would be mirrored relatively often.  But with enough scripts running simultaneous file comparisons, I'd start to take a performance hit.

Lacking a better option, I did a search to learn more about Beyond Compare scripts.  The search came up with a number of interesting concepts, right there among the top ten hits.  One was the concept of automated synchronization.  Duh!  Of course.  Synchronization was the Windows term for what I wanted.  So I did a search for that, dropping Beyond Compare for the moment.  But the only thing that came of it was the discovery of Super Flexible File Synchronizer, which cost $60 for a two-year license (unless, for some bizarre reason, I would think that I could do without the pro version's ability to copy ZIP files!).  It did look like it might have some advantages over Beyond Compare, such as the ability to detect that I had moved a folder, so that it could just repeat the move rather than delete the folder from one location and create it in another (which might involve a lot of copying, if it was a large folder).  It had very good ratings on CNET.  I could download and try it out free for 30 days.  But it was ultimately still a backup program, running on a schedule, not a mirroring program, so I was still basically working with the same scenario:  design a set of backup scripts, profiles, or whatever, and set them to run at different frequencies, backing up what I would consider the most heavily used folders most frequently.

TopTenReviews ranked Super Flexible File Synchronizer eighth in its list of sync programs.  Their comparison page had a number of relevant criteria, including the ability to do bidirectional sync, to mirror files, and to operate across a network.  It actually looked like their number two program, GoodSync ($19.95), had better features for my purposes than their number one choice, Syncables 360 ($39.95).  Their review of GoodSync made it sound good indeed.  They said it couldn't sync or merge Microsoft Outlook files, which was OK because I was using Thunderbird.  (Later, I encountered a review by a user who said s/he was using it for this purpose, so I assumed they had updated the program.)  They said that working over networks could be complicated.  I wasn't sure if they meant that as a generic remark that would be relevant to all kinds of work over networks.  They seemed to rank it number two rather than one because it "lacks some of the advanced features professional users expect."  CNET's review likewise ranked it number two, but in the category of "file management."  I wasn't sure what they considered the number one program; their webpage didn't indicate which criterion they used for that ranking.  But GoodSync was the most frequently downloaded program during the prior week.  GoodSync's awards webpage mostly listed awards and positive reviews that were at least a couple of years old.  So apparently it had been created and was now coasting.  I did a search among its many reviews on CNET, looking for more info about using it on a network.  Unfortunately, CNET's links to specific reviews weren't working for me at that point, so I wasn't able to get details, but what I was able to read from the summary results was positive with the exception of one person for whom GoodSync did not work well.

There were hardware options.  SyncSharp offered a device that would synchronize via USB.  It sounded similar to The Tornado and to the Windows 7 Easy Transfer option.  I didn't want an additional device, and since ethernet was faster and was already in place, I didn't want to use USB.  For purposes of speed and also capacity, not to mention reducing dependency on external data sources, I was obviously not going to be interested in a cloud (i.e., web-based) solution, even if I had found one that offered constant, continuous, real-time synchronization.

It turned out that CNET had another category, for "data transfer & sync software."  As with some other CNET searches, I looked at the top 30 both in terms of downloads last week and user ratings.  Setting aside those that were for special purposes (e.g., Blackberry, Outlook), and focusing on those that were for Windows 7, I found that only two were free:  CopyTo Synchronizer, which had only two votes and which I therefore deemed insufficiently tested, and Microsoft Live Mesh, which had only one vote but which I was willing to assume was better developed.  The nonfree alternatives that came up in this search included BeyondSync, ViceVersa Pro, Easy Computer Sync, and Syncables 360 Premium.  I reduced this set to Live Mesh, Beyond Sync, and ViceVersa.  A search for further information on Live Mesh suggested it was web-based, more like DropBox, leaving me to focus on the other two.  A search led back to a TopTenReviews comparison -- it may have been the same one as before, but a couple of weeks had passed by thie time -- naming GoodSync (above) as No. 2, ViceVersa as No. 5, and BeyondSync as No. 10.  Of the ten, the ones offering bidirectional sync, network synchronizing, and Windows 7 support were these three plus Syncables 360, SugarSync, Laplink, and Super Flexible.  Most of the same names also appeared in a CEOWorld review.  I eliminated SugarSync as another cloud solution.  The TopTen review for Beyond Sync made it sound unappealing.  A dotTech review echoed that. 

I ran a search looking for comparisons of Syncables against the others that also sounded good for bidirectional synchronization.  A couple of reviews alerted me to the feature, evidently present in GoodSync but not all others, of being able to see which changes would overwrite.  I began to get a sense that Syncables was more of a glossy product, designed for people who wanted simple and trouble-free synchronization without necessarily having an option to scrutinize every step of what was happening.  Having been burned by the occasional backup program that would not save (and would also not tell me that it was not saving) files of a certain kind, or nested too deep, or had an umlauted character in their filenames, or were otherwise secretly exempt from what I thought was happening, I had become more inclined to use transparent software.  At least until I gained a lot of trust and experience with a program, I wanted to see what it was doing.  So this feature of GoodSync appealed to me.  I noticed, also, that a review described Liuxz Sync as being "of most use to users that need to carryout real time synchronizations over a network or between hard drives."  As I continued to look at other opinions, ViceVersa still sounded relatively good too.

On this basis, I decided to start with GoodSync, as described in a separate post.  After some days of using it, and comparing its results against an external backup drive via manual comparisons using Beyond Compare (as described in more detail in that other post), I concluded that GoodSync was a good product for this purpose.  I set its sync rules so as to check most frequently those partitions in which I was most likely to make changes.  For practical purposes, I could change files on one computer and I would see those changes on the other computer when I went looking for them.

In short, I wound up using GoodSync to synchronize files on two computers on a home network.  The files were generally available on the other computer within minutes.  I did this without using a server.  That is, the files were available locally on each computer, so that I could keep right on working if the other one went down.  I arranged backup via external drive, and I occasionally checked that external drive against the internal drive manually using Beyond Compare.  I had better performance than on a network, and was not very vulnerable to network problems; presumably I could have set up the same arrangement via crossover cable, without even having a router.  This really felt like a solution that I had been seeking for years.