Many companies aren’t large enough to actually warrant sufficiently complex architectures that combine VTL+PTL or DiskBackup+PTL – they want the simplicity of plain old tape, but they’re forced down the more complex path due to the inability to work reliably with tape at lower speeds. I.e., there’s room in backup for multiple speeds of tape – the ultra high speed for those organisations needing to push through hundreds of terabytes of data, etc., but also the high capacity/lower speed systems. I.e., enterprise tape development has been focused at growing at the top-end of the environment, forgetting that the bottom-end of enterprise data storage is growing as the amount of data kept by even small-medium businesses continues to creep.

(Oh, and final thing – I wouldn’t necessarily consider that the LTO format is going to finish at 6 – after all, when I first started working with LTO, they had only published forward-looking plans for G1/G2/G3; not long after they published plans for Ultrium 4, and now we have LTO-5 approaching with v6 defined – i.e., if it can be added to, it will be added to.)

If not, then it’s better to know sooner rather than later.

It’s not like long-term backup and archiving will suddenly go away. Who knows, perhaps we’ll have SSD cartridges instead of tape cartridges, or perhaps holographic storage will stop being “10 years away” at some point. We also have the memristor now, and that can hold data even when the power is off as well.

There had been whispers a couple of years ago that HP and Certance had gone into an agreement to partner on LTO-5 drive/tape development, and I certainly can’t see IBM missing the boat on this one given the investment they’ve made in LTO-5. I suspect we’ll just see other vendors take their time – after all, LTO-4 is still in the happy/high part of its release and product cycle at the moment.

http://www.theregister.co.uk/2009/08/13/imation_lto5_media/

As it is, tape is cheap, has high density and is very reliable. Speed isn’t (usually) an issue when pulling data off of old media. We’re willing to trade the ability to make a lot of tapes that will last a very long time for the same price of media with an indeterminate lifespan that is very fast.

When it’s crunch time, you go with reliability every time.

IMHO, the mistake made by a lot of vendors in particular, is assuming that for backup to evolve tape has to die. This isn’t the case, and if anything just smacks of the tail trying to wag the dog. Backup is in actual fact continuously evolving, exemplified in this case by altering where tape is used in the process.

Backup to disk (regardless of virtual tape or, using NetWorker terminology, advanced file type devices), has now effectively become an entrenched and accepted strategy for appropriate backup infrastructure design. As much as it’s there to allow rapid recovery of recent backups, one of the other purposes of backup to disk is to enable the better use of high speed tape. This is achieved by reducing the number of paths or points in the environment that need to be optimised to allow streaming transfer of data to tape. Instead of the entire datazone/infrastructure having to be tuned to the hilt so that any one backup can keep high speed tape streaming, the infrastructure can instead be tuned so as required to allow the meeting of backup/recovery windows, with just the backup servers/storage nodes that need to write to tape configured for maximum tape transfer speeds.

http://www.clipper.com/research/TCG2008009.pdf

As Curtis Preston mentioned in LISA ’06:

http://www.usenix.org/event/lisa06/tech/#friday

Tape-only backup (D2T) is dead, but tape itself (in D2D2T) is very handy if you have to keep around data for a while (90+ days in the above study). It’s a matter of access time and frequency: if you want speed, then tape restores may take a while, but if you can wait a while it’s hard to beat.

At LISA ’07 Andrew Hume talks (00:18:00) about tape, amongst other things:

http://www.usenix.org/event/lisa07/tech/tech.html#hume