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Comment by simias | Hacker News Reader

For archival spinning rust is still massively more cost effective than SSDs while offering better performance than tape, especially for random access.

I'm sure eventually SSDs will be cheap enough that HDD will go the way of the floppy but we're not there yet.

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You can't use flash storage for reliable unpowered archival. It degrades (gates leak electrons) over time, unlike magnetic storage. This is also unpredictable, as reliability depends on both operating and power-off temperatures, as well as existing wear. See: https://www.anandtech.com/show/9248/the-truth-about-ssd-data...

Is tape even cheaper than spinning rust? Last time I priced it, the per-GB costs were similar and the tape drives themselves are quite expensive. Tape is a more reliable backup, since the moving parts are not part of the storage, but it's not a cheaper backup.

You might well be right, I haven't bought tape in a long time.

You can have an amount of tapes as large as you wish to a single drive, meaning the cost of the tape drive becomes irrelevant after a certain amount of tapes.

I know Amazon prices aren't exactly perfect for enterprise storage costs, but they imply tape is at least 4x cheaper (assuming you are using enough to amortize the cost of the tape drive):

6.25TB tape is $28 : https://www.amazon.com/HP-HEWC7976A-Ultrium-6-25TB-Cartridge...

6TB HDD is $120 : https://www.amazon.com/Seagate-Expansion-Desktop-External-ST...

EDIT: Commenter below points out this 6.25TB tape is actualy 2.5TB physical -- still cheaper, in terms of $/GB, but not the 4x I mention above -- closer to 2x.

That's an apples-to-oranges comparison. The "6.25TB" number for LTO tapes is assuming a fairly arbitrary 2.5:1 lossless compression ratio. The actual data capacity of the tape is only 2.5TB.

You're right. Though, that's still 2x cheaper in terms of $/GB.

You've got the wrong info, LTO-7 is 6TB and $67: https://www.amazon.com/Fuji-Ultrium-7-Data-Cartridge-1645657...

LTO-6 (what you linked) is not 6.25TB, it’s 2.5TB, despite what Amazon says.

Then add the operational costs, which is the hard part, because the operational costs for a tape are very different from the operational costs for a hard disk.

Depends on your volume. I don't know how much IT departments typically pay, but on Amazon, hard drives start at about $20-25/TB, whereas LTO-7 tapes are about $10-12/TB. That's a significant savings, but you need to be storing at least a few hundred TB before you recoup the cost of the tape drive.

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