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We've backed up our data on LTO tapes for years and it's a real comfort to know we have everything on tape. A sister project and one of our data providers have both moved to 100% disk storage because the cost of disk has dropped so much. When we propose systems to potential customers these days we tend to downplay or not mention our use of tape systems for data storage since it might seem outdated.

I feel more comfortable with having data saved in two separate formats: disks and tape. In addition, once data is securely written to tape, I feel (perhaps naively) that it's been permanently saved. Not having to rely on a RAID controller to be able to read back data is another plus for me.

Do you see a place for tape backup these days?

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7 Answers 7

up vote 25 down vote accepted

The main advantage of tapes is that it's easy to put them into a rotation scheme and store them off-site for long term backup. You can do the same with disks, but usually they're not that easily fitted into a rotation cycle, and you'll have to store them carefully to avoid damaging them (same goes for tape as well of course, but they're easier to handle).

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6  
upvote for tape durability. that's about the only attribute of tape that would be superior to disks. SSD however, that would win out. SSD is certainly more expensive. –  p.campbell Apr 30 '09 at 21:56
    
We've make some calculations few years ago. Tape devices (storage libraries) are much more cheaper than HDD storages. And cost per 10 TB are much cheaper. But this solutions start with 30k+ usd. –  MealstroM Nov 5 '13 at 14:31

There are still application for tape storage because their failure rates are so much lower than hard drives and the storage density and transfer speeds are constantly being upgraded.

And yes hard drives may be inexpensive, but when you start having various setups with redundancies and back-ups and gigabit network connections, etc it quickly becomes less and less cheap.

Read this: http://www.newscientist.com/article/mg21628875.500-cassette-tapes-are-the-future-of-big-data-storage.html#.Unj8RdKVOSo

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Offsite is probably the most important part of tape backup. The other important aspect is history, ie, you get a snapshot of what was the file contents as of a certain date.

You can do this with disks if you take snapshots and push them to a remote site, possibly more than one remote sites. Sun has products to do this, and, I'll bet that emc, netapp, ibm, hp, etc all can do this as well. The finance and drugs industry care deeply about these sorts of backups.

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The last time I investigated a tape solution was less than a year ago, and it was still cheaper than disk, sadly.

One thing that was not considered in the analysis - important to me but ignored by management - is that it is easy to protect a tape. They take a long time to erase, and they can be taken offsite easily. When all backups are on disk, all of your data can be destroyed instantly.

Remember that your tape solution should include regular test restores, verifications from users that data they think is important is backed up, and alerting of failures due to a jukebox flaking out, bad drives, etc.

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Well, since you asked, when I think 'tape storage' I think 'pain-in-the-ass write-only memory'. I fully accept that this is probably very unfair of me, but that's my association, and I'd always rather have data on disk, given the option.

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In the backup environment I manage we have two tape libraries. One is an LTO-2 Library and the other is IBM TS1120's.

On average we can store upwards of 1TB of data per tape, at a cost of about $50 per. Our primary library has a rough capacity of 750TB and uses the space of about 12 floor tiles and very little power.

Disk storage is definitely on the rise, but when using enterprise backup software, you can utilize disk technologies to store your active data, leverage de-duplication and snap-shotting, cross-site synchronization, and still put older versions of data away on tape.

Tape is also very useful to satisfy many audit requirements which force you to store large amounts of data, such as email, for long periods of time (7 years).

The short answer is, yes, tape is still very much alive and has a place in the enterprise and it will for the foreseeable future.

You can easily satisfy your speed requirements by storing active data on disk and long term data on tape, and you will have the flexibility of sending tapes off-site for disaster recovery purposes.

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Our pattern is to write data once and read never if possible. (We test our tapes occasionally, but we try to keep a working data set online.) Once a tape is full, we put it in a cabinet where they collect dust. Our customer has a packrat mentality so we never throw any data away. There's no particular cost to archiving the data beyond the cost of the tape itself and keeping the cabinet cool. Once in a while, we buy more tapes to expand our storage potential.

Our sister project stores similar data to disk. When a partition fills up, the partition gets changed to read only. The entire RAID system must remain online and consume rack space for the life of the project. Fortunately, they produce somewhat less data, so they probably won't exceed their current storage.

Projects that have very large storage requirements, do not require everything to be online at once and must preserve everything would do well to look at tape storage even in the era of terabyte disks. But it's not the cut-and-dry decision it once was.

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