Reply to post: Re: LTFS and ugly ducklings: LTFS pitfalls

LTFS and ugly ducklings

Chris Mellor 1

Re: LTFS and ugly ducklings: LTFS pitfalls

A vendor sent me these points about LTFS:

I would like to invite you to examine a list of caveats that ALL LTFS adopters need to pay attention to before they simply abandon whatever "proprietary" software they are currently using before moving all of their eggs into that LTFS basket.

In truth, this issues with tape and the general storage population were more related to capacity and performance rather than any problems with vendor lock-in. When a user chose a vendor's solution, they generally standardized on that solution - whether a tape technology or a software model - so not being able to read a DTL tae in a VXA drive was not at the heart of any displeasure on the part of the user. Rather more that they needed a week and major automation or staffing investments to create a backup to the existing tape technologies when they could accomplish the same apparent backup to a disk array in hours with no addition staff or education requirements.

The sad fact is that the tape drive vendors solved the primary issues with the advent of LTO-5 technology. With a proven throughput of 140MB/sec - 200MB/sec and capacities of 1.5TB to 2TB per tape (real numbers, not mythical marketing fluff), the capacity and performance issues became non-existent.

It was actually the unexpected and undisclosed announcement of IBM at NAB in 2011 (the remaining LTO.ORG members weren't even aware it was happening at the time) that has caused further fracturing in the market space as many existing tape software vendors were improving their tape support and offering much more robust solutions thanks to the combination of capacities and performance of the LTO-5 technology. Now, the LTO.ORG members had just placed a shot across their bows that warned that the work that so many had done for so long was now no longer applicable.

There are many aspects of tape that LTFS does NOT take into account, however. No verification of data written to the tapes. No mechanism for spanning writes across multiple tape volumes. Serious recovery issues if a reset or power glitch occurred during the writing of data to an LTFS tape. No easy way to track tapes that are not currently mounted on your system.

And my favorite glitch - there's no single point of support for an LTFS user when things go wrong (and they quite often go VERY wrong). Since it's open source, it's pretty much a case of "you broke, you get to keep all the pieces" when you need help. The response is generally "the source code is freely available..." But, how many small businesses or production companies have staff who are familiar with low-level C/C++ coding at the kernel level with a complete understanding of the low level operation of tape devices? On the other hand, that "openness" can also result in many splinter implementation as users decide that they can do this or that better.


I've anonymised the post in case the vendor meant it for me privately - but the points are the points.


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