till-tum · HackerTrans

6 miesięcy temudiscuss

For a lot of use cases such as caching (e.g., the ephemeral caching layer in Snowflake), ephemeral storage is good enough. If you really want to, you could also achieve persistence by replicating to multiple instances (afaik this is what DynamoDB does)

till-tum

6 miesięcy temudiscuss

I don't think this can be definitively answered without working for one of the hyperscalers. But here are some speculations: 1. Device speeds are intentionally capped to increase device lifetime (but this would only make sense for writes) 2. Networked storage services like EBS are more profitable, and AWS would like to phase out instance-attached storage. 3. Technical limitations/virtualization overhead (See comment above). I don’t have enough insight of how AWS SSDs work under the hood, but high network throughput (600 Gbit/s) is possible even in virtualized instances. Then again, we have certainly seen some weird noisy neighbor effects on cloud SSDs. However, it's worth mentioning that the same throughput limitations also apply to bare metal instances, where users don't benefit from virtualization (https://docs.aws.amazon.com/ec2/latest/instancetypes/so.html...). 4. There’s too little customer demand for fast SSDs, and optimization is not worth the effort.

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