I recently received a question from an IT community forum:

“I’m playing around with ideas for digital asset management and archiving. We already have a Quantum Scalar i40 for backup and I’m wondering if we add a second LTO5 drive if we could effectively use the extra tape slots for an online archive?”

I couldn’t have asked for a better lead in to the topic I planned to cover this week:  LTFS use cases.

LTFS, or Linear Tape File System, is an industry open standard file system for tape cartridges. What is compelling about LTFS is one, it is an open standard format for tape, and two, it is a file system, which implies it contains file metadata as well as file content.

Item one above gives you the ability to exchange data with others, and two gives you the ability to browse the file system to see what is on the tape without having to parse the entire tape. This is what makes LTFS so much better than the other prominent standard for tape, known as TAR. With TAR, you have to scan the whole tape – a process that can take hours – just to know what files are on that tape, while with LTFS you just need to read the metadata partition of the tape. You can learn more about LTFS from this paper.

With that understood, we can easily identify some of the more compelling reasons someone, such as the inquirer above, would value the notion of using LTFS as an online archive. Here are some of the common reasons I have seen:

– Safer for storing data as an archive. If you are looking to store data for long periods of time, and particularly if this is the primary copy of that data, storing it in an open standard such as LTFS means a higher confidence level when retrieving the data. Proprietary formats don’t offer this level of assurance.

– Open standard = exchangeable. Since LTFS is an open standard, it is a great vehicle for exchanging large files or file-sets with others.

– Open standard = not tethered to specific application. With LTFS, you can write data to tape without being tied to the backup application that wrote them there. Granted, backup applications provide a lot of value in terms of revisions management, cataloging, etc., but many people I have spoken with are just looking for a simple way to take advantage of tape storage, and keep their data as independent as possible. LTFS is perfect for this.

Now, back to the original question: using LTFS as an archive in the extra slots of a library. Not only is this a perfect use case for LTFS – using the open standard for digital asset storage and archive – it is also a great way to get the most out of a tape library by using some slots for traditional backup, and other slots for archive or active-archive storage.

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