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I could be missing something, but I can't really wrap my head around "unlimited paralelism". What they say is that the logic is embedded into their server bina

I could be missing something, but I can't really wrap my head around "unlimited paralelism". What they say is that the logic is embedded into their server binary and they write to a local EBS. But what happens when they have two servers? EBS can't be rw mounted in multiple places. Won't adding the second and more servers cause trouble like migrating data when new server joins the cluster, or a server leaves the cluster? I understand Aurora was too expensive for them. But I think it is important to note their whole setup is not HA at all (which may be fine, but the header could be misleading).

klohto 3y ago
EBS can be multi attached for a long time now, no perf impact
- kroolik 3y ago
  Oh thanks! Always thought it was what EFS was for. They are still limited to the same AZ, so no multi AZ redundancy.
  - klohto 3y ago
    yea, multi AZ failover would be an issue but I assume they don’t care that much. you could spinup new EBS from the backup when the first region fails or keep a warm copy there, but seems like a lot of extra engi work.
trebecks 3y ago
i got caught up on that statement too. i interpreted it as they can spin up more servers with their own volumes but thats not really 1 ebs volume anymore. maybe at their current load they only need 1? the op mentioned copying stuff to s3 at a certain size so it sounds like the disk isn't very big at any moment. i don't think there would be much to do if another server joins. > Amazon EBS offers a higher durability volume (io2 Block Express), that is designed to provide 99.999% durability with an annual failure rate (AFR) of 0.001%, where failure refers to a complete or partial loss of the volume. if they take snapshots often enough to feel comfortable with that low failure rate, it does seem kind of reasonable to me. really low risk of a given volume failing.

klohto 3y ago

EBS can be multi attached for a long time now, no perf impact

kroolik 3y ago
Oh thanks! Always thought it was what EFS was for. They are still limited to the same AZ, so no multi AZ redundancy.
- klohto 3y ago
  yea, multi AZ failover would be an issue but I assume they don’t care that much. you could spinup new EBS from the backup when the first region fails or keep a warm copy there, but seems like a lot of extra engi work.

trebecks 3y ago

i got caught up on that statement too. i interpreted it as they can spin up more servers with their own volumes but thats not really 1 ebs volume anymore. maybe at their current load they only need 1? the op mentioned copying stuff to s3 at a certain size so it sounds like the disk isn't very big at any moment. i don't think there would be much to do if another server joins. > Amazon EBS offers a higher durability volume (io2 Block Express), that is designed to provide 99.999% durability with an annual failure rate (AFR) of 0.001%, where failure refers to a complete or partial loss of the volume. if they take snapshots often enough to feel comfortable with that low failure rate, it does seem kind of reasonable to me. really low risk of a given volume failing.