Archiving #2: tape vs. drives
Having basically ruled out optical storage, we’re left with two major archiving options: data tape and hard drives.
The leading high-end data tape format is LTO-3. Drives are available from many vendors, and you can expect to pay upwards of $3500. Tapes are 400 GB, and cost around $55 if you shop around, though you have to buy tapes in 20 packs (over $1000) to get prices like that.
This makes LTO-3 media a lot cheaper than hard drive space; it’s about $0.14/GB, or $0.23 per minute to store REDCODE RAW 4K footage. In contrast, you can get a 500 GB hard drive for around $200, which gives you a price of $0.40/GB or $0.66/minute for that Red footage.
But, of course, you have to take into account that big up-front cost for the tape drive. When does that pay itself off? Let’s do some math.
Assume $480 for a 1 TB hard drive (Hitachi is shipping these in Q1 in an external case (or a bay of a multi-bay external case, much more on these in a later post), and $4000 + $60/tape on the tape side (a price you can get without buying a thousand bucks worth of tape at once).
At these rates, the tape drive pays for itself when you’ve got 12 TB worth of data to store. If you’re storing 24 TB of data, tape is down to $0.32/GB, while hard drive storage is still $0.48/GB. For 40 TB of storage, tape is down to $0.25/GB.
So, which should to pick? Well, tape is a bit of a hassle vs. hard drive storage (much more on this aspect of archiving in a latter post). And 12 TB is a good bit of storage, even for 4K (well, compressed with REDCODE, anyway). It’s enough storage for ~120 hours of footage. If you’re making a documentary or a reality TV program you’ll probably need more storage than that fairly quickly, but that’s enough storage for all the footage comprising ten 100 minute narrative features shot at a 7:1 shooting ratio. It’s probably going to take a while to shoot ten movies, by which time hard drives will probably be more competitive, since hard drive prices tend to drop faster than tape prices.
Based on these numbers, this one is going to be a tough call for a lot of people.
[...] If we’re building a 2 TB array out of 500 GB drives, why do we want five of them, rather than four? Well, if you create a striped RAID across four drives, and any one of them fails, your data is toast. Even if you leave them as separate volumes, if any one of them fails, 1/4 of your data is toast. And, of course, you’re four times as likely to have a failure with four drives as with one. Sure, hopefully you’ve got everything backed up, but you could still lose a fair bit of work. [...]