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Commentary from a long term NetWorker consultant and Backup Theorist

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Posts Tagged ‘tape’

Funny attitude adjustments

Posted by Preston on 2009-12-08

It’s funny sometimes seeing attitude adjustments that come from various companies as they’re acquired by others.

One could never say that EMC has been a big fan of tape (I’ve long since given up any hopes of them actually telling the 100% data protection story and buying a tape company), but at least they’ve tended to admit that tape is necessary over the years.

So this time the attitude adjustment now seems to be coming from Data Domain as they merge into the backup and recovery division at EMC following the acquisition. Over at SearchStorage, we have an article by Christine Cignoli called “Data deduplication goes mainstream, but tape lives on“, which has this insightful quote:

Even Shane Jackson, director of product marketing at Data Domain, agrees. “We’ve never gone to the extreme of ‘tape is dead,'” he said. “As an archive medium, keeping data for seven years for HIPAA compliance in a box on a shelf is still a reasonable thing to do.”

That’s interesting, I could have sworn I have a Data Domain bumper sticker that says this:

Data Domain Bumper Sticker

Now don’t get me wrong, I’m not here to rub salt into Data Domain’s wounds, but I would like to take the opportunity to point out that tape has been killed more times than the iPhone, so next time an up and coming company trumpets their “tape-is-dead” story, and some bright eyed eager and naïve journalist reports on it, remember that they always come around … eventually.

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Posted in Backup theory, General Technology | Tagged: , | 2 Comments »

Quibbles – The maddening shortfall of ADV_FILE

Posted by Preston on 2009-11-25

Everyone who has worked with ADV_FILE devices knows this situation: a disk backup unit fills, and the saveset(s) being written hang until you clear up space, because as we know savesets in progress can’t be moved from one device to another:

Savesets hung on full ADV_FILE device until space is cleared

Honestly, what makes me really angry (I’m talking Marvin the Martian really angry here) is that if a tape device fills and another tape of the same pool is currently mounted, NetWorker will continue to write the saveset on the next available device:

Saveset moving from one tape device to another

What’s more, if it fills and there’s a drive that currently does have a tape mounted, NetWorker will mount a new tape in that drive and continue the backup in preference to dismounting the full tape and reloading a volume in the current drive.

There’s an expression for the behavioural discrepancy here: That sucks.

If anyone wonders why I say VTLs shouldn’t need to exist, but I still go and recommend them and use them, that’s your number one reason.

Posted in NetWorker, Quibbles | Tagged: , , , , , | 2 Comments »

When will tape die?

Posted by Preston on 2009-08-10

As you may have noticed, I have a great deal of disrespect for “tape is dead” stories. To be blunt, I think they’re about as plausible as theories that the moon landing was faked.

So I thought I might list the criteria I think will have to happen in order for tape to die:

  1. SSD will need to offer the same capacity, shelf-life and price as equivalent storage tape.

There’s been a lot of talk lately of MAIDs – Massive Arrays of Idle Disks – being the successor/killer to tape, on the premise that such arrays would allow large amounts of either snapshotted or deduplicated data to be kept online, replicated into multiple locations, and otherwise in a night-perfect nearline state.

This isn’t the way of the future. Like VTL, MAIDs are a stop-gap measure that will fulfill specific issues to do with tape, but not replace tape. Like VTLs, if the building is burning down you can’t rush into the computer room, grab the MAID and run out like you can with a handful of tapes. Equally similarly to VTLs and disk backup units, it’s entirely conceivable of a targetted virus/trojan (or even a mistake) wiping out the content of a MAID.

No, we won’t get to the point where tape can “die” until such time as there is a high speed, safe, and comparatively cheap removable format/media that offers the same level of true offline protection.

The trouble with this is simple – it’s a constantly moving goalpost. Restricting ourselves to just LTO for the purposes of this discussion, it’s conceivable that SSDs might, in a few years, catch up with LTO-4; however, with LTO-5 due out “soon”, and LTO-6 on the roadmap, SSDs don’t need to catch up with a static format, they need to catch up with a format that is continuing to improve and expand, both in speed and capacity.

So perhaps, instead of being so narrow as to suggest that tape might die when SSDs catch up, it might be more accurate to suggest that tape may have a chance of being replaced when some new technology evolves with sufficient density, price-point, performance and portability that it makes like-for-like replacement possible.

There are “old timers” in the computer industry who can tell me stories of punch card systems and valve computers. I’m a “medium timer” so to speak in that I can tell stories to more youthful people in computing about working with printer-terminals, programming in RPG and reel-to-reel tape. So, do I envisage in 10-20 years time trying to explain what “tape” was to people just starting in the industry?

No.

Posted in Architecture, Backup theory, NetWorker | Tagged: , , , , | 7 Comments »

Thinking green? Think tape

Posted by Preston on 2009-06-27

Many companies are now becoming increasingly aware of the importance of either achieving carbon neutrality, or at least being as green as possible.

If your company is trying to think green, then let me ask you this. For long term backup storage, which of the following two is likely to be more energy efficient?

  • Writing backups to tape which is then stored in a temperature controlled room,

or

  • Writing backups to disk arrays which are kept in temperature controlled rooms and permanently running.

Much has been said of late about deduplication this, or deduplication that, and I’ll agree – deduplication is a valid and important emergant technology in the field of backup and recovery. But it’s not a silver bullet, regardless of how many disk storage vendors want it to be. The problem is that many of the deduplication products currently touted are ineffectual at high speed “tape-out” operations, and thus, rely on keeping backups on-line on disk – with replicas maintained to another location. That’s a whole lot of spinning disk.

The simple fact of the matter is that not only is offline tape safer than spinning disk drives, it’s also considerably more power efficient.

I want it clear here – I’m not arguing that all backup should go exclusively to tape. There’s a middle line between green and practicality that remains necessary to be walked, meaning that more frequently accessed backup for many companies needs to be in some disk form initially.

Long term backups, archives, and offsite copies however are all forms of backups that should be on green, safe technology – and that’s tape.

If you want to think green in your datacentre, think tape.

Posted in Backup theory, NetWorker, Policies | Tagged: , , , | 3 Comments »