Why would you ever want to use tape instead of a HDD?

Question

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Advantages/Disadvantages of using tape instead of disk

As I've never used a tape drive, this is probably a naive question.

I was always guessing that tape must probably be cheaper which is why people would want it. But then I read this Slashdot comment which basically says that:

• tape drives have crappy latency
• tape drives are not as reliable as multiple hard drives
• tape drives are extremely expensive for such a small (1.5 TB) storage capacity

Furthermore, on that ask Slashdot thread, it is established that the read speed is just OK, nothing great.

So why would I ever want a tape drive? It seems to me that it is simply made obsolete by HDs. Or am I wrong?

Answer 1

History!

Quite frankly, go back many years and it was simply the thing to do for backups - many of the negatives were simply not a concern for the requirements.

Every IT Department I knew would have tape rotations, schedules and just do it without thinking - when storage needs increase, they buy the latest tape technology and keep upgrading whilst trying to minimise change to business processes.

As time goes on, disks are becoming cheaper and cheaper and backup to disk is becoming the normal.

Give it a few more years and I would expect tapes to be history as always on disk based backup has so many advantages.

Answer 2

Until recently, tape drives were the only realistic way to securely back up large quantities of business data. Latency was not a problem with backups so is irrelevant in many cases. The reliability of tape drives was far better than low cost drives as long as you didn't over use the tapes - a very common problem with organisations that tried to cut costs without thinking.

However, over time, hard drives have continued to innovate and change. Becoming both cheaper and more reliable as well as larger.

This has changed the whole realm of backup so that tapes are now rarely worth the effort or money.

However, there is a "gotcha" - tape media was not that easy to overwrite or change but disks are very easy to change. So make sure that you are actually doing a "backup" not a "copy" which is a very different thing. Backups are hard to delete or change. You also need to allow for rotation of backups or for keeping historic data somehow. Rotation is not so easy for disks as they are more vulnerable when moved, most disk-based backups use versioning to keep historic data. You also need to ensure that backups are kept in multiple locations - generally, with tapes, this was done by rotating tapes first to an on-site safe and then to offsite storage. With disk-based backup, you need an alternative such as a cloud-based solution like CrashPlan. An onsite-only solution is worse than useless as it makes you feel secure when you certainly are not.