Comment by hinkley
5 days ago
> Once upon a time Glacier was its own service that had nothing to do with S3. If you look closely (hi, billing data!) you can see vestiges of how this used to be, before the S3 team absorbed it as a series of storage classes.
Your assumption holds if they still use tape. But this paragraph hints at it not being tape anymore. The eternal battle between tape versus drive backup takes another turn.
I am also assuming that Amazon intends for the Deep Archive tier to be a profitable offering. At $0.00099/gb-month, I don't see how it could be anything other than tape.
I wonder if it's where old S3 hard drives go to die? Presumably AWS have the world's single largest collection of used storage devices - if you RAID them up you can probably get reliable performance out of them for Glacier?
Not quite. Hardware with customer data or corp IP (eg any sort of storage or nvram) doesnt leave the "red zone"[1] without being destroyed. And reusing EOL hardware is a nightmare of failure rates and consistency issues. Its usually more cost effective to scrap the entire rack once its depreciated, or potentially at the 4-5 year mark at most. More revenue is generated by replacing the entire rack with new hardware that will make better use of the monthly recurring cost (MRC) of that rack position/power whips/etc.
[1] https://www.aboutamazon.com/news/aws/aws-data-center-inside
I still don't know if it's possible to make it profitable with old drives in this kind of arrangement, especially if we intend to hit their crazy durability figures. The cost of keeping drives spinning is low, but is double-digit margin % in this context. You can't leave drives unpowered in a warehouse for years on end and say you have 11+ nines of durability.
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You don’t raid old drives as it creates cascading failures because recovering from a failed drive adds major wear to other drives
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My understanding is some AWS products (e.g. RDS) need very fast disks with lots of IOPS. To get the IOPS, though, you have to buy +++X TB sized SSDs, far more storage space than RDS actually needs. This doesn't fully utilize the underlying hardware, you are left with lots of remaining storage space but no IOPS. It's perfect for Glacier.
The disks for Glacier cost $0 because you already have them.
Since ~2014 or so the constraint on all HDD based storage has been IOPs/throughput/queue time. Shortly after that we started seeing "minimum" device sizes that were so large as to be challenging to productively use their total capacity. Glacier type retrieval is also nice in that you have much more room for "best effort" scheduling and queuing compared to "real time" request like S3:PutObject.
Last I was aware flash/nvme storage didnt have quite the same problem, due to orers of magnitude improved access times and parallelism. But you can combine the two in a kind of distributed reimplementation of access tiering (behind a single consistent API or block interface).
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http://www.patentbuddy.com/Patent/20140047261
Is tape even cost competitive anymore? The market would be tiny.
One way to know is to see if new tape products exist, indicating ongoing development. As of May, 2025, LTO-10 is available, offering 30TB/75TB (raw/compressed) storage per cartridge. Street price is a bit under $300 each. Two manufacturers are extant: Fujifilm and IBM.
It's gone in cycles for as long as I recall and older devs around 2010 said it had been going on for as long as they could recall.