The release by IBM of the Linear Tape File System or LTFS has made it very easy for just about anyone to setup a file system interface to a tape library. Tape libraries have always held the promise that slow, huge, cheap storage could offload a large portion of the unstructured data currently clogging the servers. The passed-around statistic that "60% to 80% of the data stored hasn't even been looked at in over a year" would seem to be a market made in heaven for tape libraries. Wow, if we could just move this dead data (is the new term Dark Data now?) off to tape, we can recover huge amounts of online capacity resulting in huge storage savings. That would be amazing. Hey, now all we have to do is download LTFS and we are all set!
Hold on. Hum. Hasn't this been tried before? How well did that work out? Why is this time different?
Over my (ah, cough...) 3000 years in the storage industry, I've seen many companies attempt such a scheme. Almost all of them were based upon some type of file system interface to the storage device. Almost all of them made the above claim. All of them failed to gain much traction. Many of these companies are long since out of business. I've personally been involved in at least a half a dozen of these projects. (Does anyone remember Magneto-Optical storage?) Why have they all failed to gain much traction? Yes, there are some special cases where they work but of you look closely, they are almost always relegated to a single application and, even worse, are only used by a single user. Nearly every computer or file server could benefit from moving off its old stuff to tape. Despite all these efforts and millions (billions?) of dollars spent on it, why has it never taken off?
Why?
Without getting into the technical details, these systems have two "Time Bombs" that have killed the products and even the industry a couple of times.
The first one we call operating system "constipation". If users, applications, or other computers are free to simply make any random accesses to such a system, it is inevitable that certain OS resources will end up being reserved for use by the library leaving nothing left for anything else. The operating system simply locks up. You often can't even log in to kill some of the processes that are locking the system up because the system is locked up. Often the only way around this is to physically pull the plug out of the wall. The funny thing is that this looks much like a hardware failure. I've seen users send their systems in for repair only to find out it was the library software the killed it. Too many of these episodes and the product gets rolled back on the loading dock.
The second, and related problem is has to do with performance. We call this the Century Problem. Even the LTFS documentation warns about "poor performance" if certain operations are attempted. The reality is that it turns out to be amazingly easy to access a library in such a way that it will literally take 100 years for the processes to finish!
There is an entire technical dissertation that could be presented as to why this occurs but here is the bottom line:
The last thing you can do is expose a tape library as a file system!
Does this mean all is lost? No. An information asset management system can solve this problem to make a tape library, or other slow, cheap, and huge storage devices available to everyone all while avoiding the time bombs.
More to come on this one....
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