What is LTO and what has it got to do with Video?

LTO stands for Linear Tape-Open. It’s just tape. There were others. This version is the last man standing.

Quantum LTO Tape

About tape

Tape is the oldest method of storing electronic data, and is extremely reliable when taken care of. Tape inherently has many drawbacks:

  • You can’t get anywhere without going through the tape from the beginning. Tape is great for serial access, but not for random access
  • Every time the tape passes through the head there is loss.
  • Tape ‘unspooled’ is a nightmare to deal with.
  • If a tape is cut the entire thing becomes useless until patched up again (which you can do with scotch tape).
  • Tape is prone to fungus.
  • Tape cannot start and stop immediately (this problem is present in spinning drives also).
  • Tape is prone to deformation if the motor system becomes unstable. Heat and cold affect both tape and the motor system.
  • Limited storage temperature range, typically between 16-35 oC
  • Limited storage humidity range, typically between 20-50% RH

But tape inherently also has advantages:

  • A cut tape is still useful when patched up.
  • Data for data, the tape is harder to destroy than a drive. Recovering data is easier, too.
  • Tape is easier to transport. It can take a lot more knocks than a spinning drive.
  • It tends to be cheaper.

 

What is LTO?

LTO is a tape-based backup system. Instead of spinning drives or solid state drives or flash memory drives, you use tape.

Just like Windows has the FAT/NTFS file system and Macs have the HFS+ file system, LTO has its own file system, called LTFS (Linear Tape File System).

Here are some quirks of the LTO system:

  • The specific version (form factor) of the tape we are concerned with is called Ultrium. This ‘entire thing’ (tape + cover) is called a cartridge. A drive that reads Ultrium tape is called an Ultrium drive.
  • LTO uses an automatic verify-after-write technology to immediately check the data as it is being written.
  • LTO is an evolving standard that is getting better with each version.
  • The main players are IBM, HP, Tandberg and Quantum.
  • A drive typically reads data from a tape in its own generation and at least the two prior generations. This is not necessarily true of all drives.
  • A drive typically writes data to a tape in its own generation and to a tape from the immediate prior generation (in the prior generation or ‘older’ format). This is not necessarily true of all drives.

Even though LTO is touted as a unique backup solution, there are some serious disadvantages, including this one, taken from Wikipedia:

Unlike a disk LTFS does not know the concept of permission and ownership. In the Unix/Linux world all files and directories on the tape are owned by root. One cannot chown or chmod items on tape. This makes LTFS unattractive as a backup solution – one still needs a third party application to manage the metadata (ownership, permission and timestamps).

On the other hand, LTO also includes an error-verification technology that immediately checks data as it is being written:

The tape drives use a strong error correction algorithm that makes data recovery possible when lost data is within one track. Also, when data is written to the tape it is verified by reading it back using the read heads that are positioned just ‘behind’ the write heads. This allows the drive to write a second copy of any data that fails the verify without the help of the host system.

What’s the bottom line? LTO is designed for more robust data storage, but isn’t the panacea that its fans claim it is. It is improving with every version, but isn’t there yet. In its favor, though, nothing else is, either.

LTO versions

LTO has six major versions, the last of which, LTO-6, was released in 2012. Each version (also called a ‘generation’) has added increased capacity with greater speed.

Here’s a general table highlighting the differences in versions or generations*:

Version Capacity Durability – Entire tape reads/writes Approx. years of life Max Speed (MB/s)
LTO-1 100 GB 200 17 20
LTO-2 200 GB 250 21 40
LTO-3 400 GB 364 30 80
LTO-4 800 GB 200 17 120
LTO-5 1.5 TB 140
LTO-6 2.5 TB 160
LTO-7** 6.4 TB 315
LTO-8** 12.8 TB 472

*This is an approximate table and the values are not true for all makes and models. Check the manufacturer’s specifications for correct values.**These are future versions yet to be announced. The current standard is LTO-6, while the ‘most common’ is probably LTO-5.LTO Tape Drive

What has LTO got to do with video?

As you can see from the above table, the current generation of LTOs – LTO-5 and LTO-6 are on par with spinning hard drives in terms of capacity and data transfer speed.

In regular use, hard drives win easily. You can connect them to a computer and access the exact shot in a matter of seconds. This isn’t possible with tape.

Tape is touted as a backup solution. But it shouldn’t be confused as an archival solution, even though many people incorrectly believe this. The major manufacturers offer a limited lifetime warranty on LTO tape cartridges and up to 3 years for the drives. An LTO tape is supposed to last for up to 30 years but that is not my definition of an archival period.

All right, then. Tape has many disadvantages, and it can’t be used like regular hard drives. It isn’t an archival solution but its structure and file system is designed for reliability in the short term, making it a decent backup solution. Whether or not this is better or worse than hard drives is irrelevant for most video professionals for one reason:

Price.

Here’s what you need to get started:

  • A typical 1.5 TB LTO-5 tape cartridge runs about $30 (when bought as a pack).
  • A typical LTO-5 drive costs about $2,000. If you’re serious about LTO backup you’ll have at least two drives.
  • You’ll need an LTO cleaning tape, which costs about $50.
  • Plus, you’ll need a computer and cables.

On the other hand, a 2 TB hard drive costs about $100. You don’t need a ‘drive’ because you just have to connect to the computer via SATA, eSATA, USB 3.0 or Thunderbolt.

If you wanted to backup 1.5 TB of data, you could purchase 3 drives and have 3 copies, and then transfer these copies to new versions of the drive every year. In three years, you’ll have used up 9 drives, which will run you about $900.

In the same period, you’ll have spent slightly more than $2,000 for the LTO version. LTO tapes and drives need upgrading, maintenance, etc. just like hard drives. Therefore, it makes no sense whatsoever to use LTO tapes for 1.5 TB.

But what about 15 TB? You’ll spend $2,500 for LTO, and about $6,500 for drives if you transfer them every year. See the advantage?

This is why LTO is used as the backup solution for feature-length and documentary projects – it is cheaper and supposedly lasts longer than hard drives. It has a file system that tries its best to protect data, and its service is enterprise-quality. Insurance companies love LTO for these reasons.

Obviously, the above example is simplistic, but it will give you an idea on how to estimate costs to see if LTO is worth the expense in your case. You’ll always need more than one LTO drive, and multiple copies of LTO tape just like hard drives.

4 replies on “What is LTO and what has it got to do with Video?”

  1. Hi,
    Awesome thanks for sharing this information, it is really useful and
    Lto-7 tape has a large storage capacity of 6.4TB. This tape is very useful in large scale business.

  2. Hello,
    (I apologize for my low level wrinting in english). I Read your post and I’m satisfied with all the information that you provided, but I have a simple question: I start a featute film like DIT the next week and a I proposed to the producer that Backedup on LTO-6 tape all RAW media of the project. We will film with Alexa cameras in ARRIRAW, the question here is if those LTO-6 tapes are going to be of 2.5TB (raw data) or 6.5TB (compression data)? I sure that those boxes will keep 2.5TB but I have doubts on that.
    Thanks!!

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