Tape drives have multiple heads for IO, which allows some to fail along the way and you can still read/write your data. This sounds good - but it actually just means these tape drive heads are flaky. What do you do when too many fail? You call IBM or whoever and get them to replace your tape drive, or "reman" it by replacing the failed heads. This is the only way they actually achieve their warranties around lifetime read/writes.. they assume you'll fix the hardware along the way.
These HAMR drives have the same problem. The "heat assisted" just means they're using a laser to heat up a piece of gold, and sometimes this means the gold kinda drips around, and the head can be ruined. So their read/write lifetime numbers are pretty loose compared to PMR, and there is an assumption you'll "reman" these drives if they start to have failed heads for IO. However, the gold can even drip onto the platter, giving you permanent data loss anyways.
Lastly, they use SMR to get this density. SMR is not like PMR. PMR is what you think of with an HDD with many small blocks either 512B or 4KiB which you can read/write to. SMR has 256MiB (or 128) "zones" that you can only append, or reset. This means instead of being able to write randomly across the drive's capacity, you need to plan out your writes across appendable regions. This complicates your GC, compaction, and reduces your total system IO. Your random read performance is still better than Tape, but this basically turns your HDD solutions into something that looks a lot more like Tape. This is incredibly unpopular technology for this reason.
The market for these things is much smaller than most HDD vendors would like. You have a few hyperscalars that have figured out how to write out backups efficiently, but they want a lot of read IO, and reducing the spindle to byte ratio means you have less total system bandwidth to your data.
This means that the price per byte would actually need to be lower than their PMR drives, let alone wildly better warranty agreements, for these to be better TCO than current generation drives.
> The "heat assisted" just means they're using a laser to heat up a piece of gold, and sometimes this means the gold kinda drips around, and the head can be ruined.
It sounds like this tech is related to MO tech, which has been used for decades without issues (see: minidisc).
The laser is said to heat the spot on the platter to a bit over 400C, while the melting point of gold is over 1000C, so that doesn't jive. Did you meant something else?
> Lastly, they use SMR to get this density.
Why do they have to? SMR is just a way of fitting more data on a disc by overlapping tracks. I don't know why it is necessary to use this method on this technology.
Because they can. I saw a tech talk from a data recovery guy and he said some vendor (sadly doesn't remember which one) just have no new CMR drives at all.
Tape drives have multiple heads for IO, which allows some to fail along the way and you can still read/write your data. This sounds good - but it actually just means these tape drive heads are flaky. What do you do when too many fail? You call IBM or whoever and get them to replace your tape drive, or "reman" it by replacing the failed heads. This is the only way they actually achieve their warranties around lifetime read/writes.. they assume you'll fix the hardware along the way.
These HAMR drives have the same problem. The "heat assisted" just means they're using a laser to heat up a piece of gold, and sometimes this means the gold kinda drips around, and the head can be ruined. So their read/write lifetime numbers are pretty loose compared to PMR, and there is an assumption you'll "reman" these drives if they start to have failed heads for IO. However, the gold can even drip onto the platter, giving you permanent data loss anyways.
Lastly, they use SMR to get this density. SMR is not like PMR. PMR is what you think of with an HDD with many small blocks either 512B or 4KiB which you can read/write to. SMR has 256MiB (or 128) "zones" that you can only append, or reset. This means instead of being able to write randomly across the drive's capacity, you need to plan out your writes across appendable regions. This complicates your GC, compaction, and reduces your total system IO. Your random read performance is still better than Tape, but this basically turns your HDD solutions into something that looks a lot more like Tape. This is incredibly unpopular technology for this reason.
The market for these things is much smaller than most HDD vendors would like. You have a few hyperscalars that have figured out how to write out backups efficiently, but they want a lot of read IO, and reducing the spindle to byte ratio means you have less total system bandwidth to your data.
This means that the price per byte would actually need to be lower than their PMR drives, let alone wildly better warranty agreements, for these to be better TCO than current generation drives.