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LTO-8 is 12tb a 12tb drive is more expensive than LTO. Even at volume. 2*6tb drives is still more expensive. However thats not the use case right, HDDs do ge
by KaiserPro 6y ago
LTO-8 is 12tb
a 12tb drive is more expensive than LTO. Even at volume.
2*6tb drives is still more expensive.
However thats not the use case right, HDDs do general storage really well.
A tape robot is the place where your data goes to rest. Its the last line in your tiered storage.
In AWS land it goes RAM->EBS->s3->glacier
tape is the same stage as glacier.
You have RAM cache (be it redis et al, or some fancy block storage) Screaming fast SSDs, but only a few TBs, Slower cheaper SSDs, but ten times as more. Then if you need lots of storage you'd have a few PB of Spinny disks.
After that it goes to Tape. Its denser, cooler and far less expensive to run than the equivalent spinny disk array.
Now this only makes sense if you have data in the PB range, and its more data than you can store online. Anything less and it doesn't make sense. It never did, its just that the capacity of storage has ballooned so much in the last 15 years that people's perceptions haven't caught up.
- Dylan16807 6y agoYou're neglecting that the tapes have to go in something. LTO-8 drives are vastly more expensive than 12TB hard drives. A pile of tapes, where the vast majority of the tapes are not in drives, is cheaper than hard drives. But then you're not getting those high speeds anymore. - Let's do some simplified math. 12TB hard drives for $26/TB, LTO-8 tapes for $9/TB, and tape drives for $3500. Since you're saving $17/TB, you need 205TB before tape gets cheaper. So 17 tapes. Each hard drive takes about 18 hours to fill. So 17 hard drives take 18 hours to fill, at a total speed of 3GB/s. Each tape takes about 9 hours to fill. So 17 tapes take six and a half days to fill, at a total speed of 360MB/s. If you have enough tapes per drive to make tape cheaper than hard drives, it's slooowwww. If you have fewer tapes per drive, it can be reasonably fast, but never as fast as hard drives. Tape has a lot of advantages. But not speed.
- caf 6y agoDoes the $26/TB for hard drives include the cost of the JBOD chassis you'll need to to have them all online at once, in order to get those speeds?
- Dylan16807 6y agoNo, but I didn't include the cost of the tape robot either. I'm seeing prices like $10k for a 6U/80 tape robot, and $10k per 80 drives is more than enough for a very fast JBOD chassis. You could more than double the budget of a Backblaze pod, and upgrading to an EPYC and 100 gigabit ethernet would only take about a thousand dollars. Also even in some ridiculous circumstance where your tape robots were free and you have to pay $7.2k per JBOD chassis, that still only bumps the cost to $36/TB and the overall analysis doesn't change much. $26/TB was an overestimate anyway. Especially when you can get 5400RPM drives for $18/TB, and it only hurts your speed by about 20%.
- beowulfey 6y agoMaybe I’m just not techy enough, but in my old fashioned mind I feel like creating petabytes of data regularly implies data cruft more than anything else. I don’t know. I have this deep suspicion that as humans we are creating more and more bits that are just building up like our plastic waste is in the universe. At the moment there is obviously no major downside, but a part of me wonders if that will always be the case...