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Amazon claims: "Each storage volume is automatically replicated within the same Availability Zone. This prevents data loss due to failure of any single hardware

by A1kmm 16y ago

Amazon claims: "Each storage volume is automatically replicated within the same Availability Zone. This prevents data loss due to failure of any single hardware component". They make it sound like they are already providing RAID or something similar; however, the fact that things like this happen to Reddit, who have built their own RAID on top of Amazon's already replicated volumes, show that reliability is not a good reason to go with AWS.

Montagist 16y ago
Yea I always kind of assumed they'd something like that - RAIDed everything, but then again I think that may be the difference between using one of their DBs and running your own atop EBS. EBS hasn't an actual file-system, right? Or does it? I think it's more raw, and I guess more "use at your own risk" apparently. Damn Amazon, not a good look. Also, why aren't dudes sending you apology fruit baskets or refunding money or something?
misterbwong 16y ago
Disk access was the single reason we couldn't go with AWS offerings. The speed/reliability of EBS just isn't where we need it to be for our database servers. I don't blame amazon for this-it's just a drawback of the their choice to go fully shared tenant and virtual.
parasubvert 16y ago
EBS isn't really RAIDed, it's virtualized block storage with replicas. The issue Reddit experienced wasn't drive failure, though, it was network degradation. The solution is to deploy redundant replicas in different availability zones (and/or regions, if you can). Reddit unfortunately wasn't built for that. This isn't really any different from an on-premise application. An availability zone by definition implies "shared network hardware". Using multiple is what you do when you want redundancy.
- snewman 16y ago
  How do you know the issue was network degradation? Is this written up somewhere?
  - parasubvert 16y ago
    The original Reddit blog post indicates there were latency problems initially. It's not clear what caused followon problems, but the latency may have triggered a bad condition for their replication.

by A1kmm 16y ago

Montagist 16y ago

Yea I always kind of assumed they'd something like that - RAIDed everything, but then again I think that may be the difference between using one of their DBs and running your own atop EBS. EBS hasn't an actual file-system, right? Or does it? I think it's more raw, and I guess more "use at your own risk" apparently. Damn Amazon, not a good look. Also, why aren't dudes sending you apology fruit baskets or refunding money or something?

misterbwong 16y ago

Disk access was the single reason we couldn't go with AWS offerings. The speed/reliability of EBS just isn't where we need it to be for our database servers. I don't blame amazon for this-it's just a drawback of the their choice to go fully shared tenant and virtual.

parasubvert 16y ago

EBS isn't really RAIDed, it's virtualized block storage with replicas. The issue Reddit experienced wasn't drive failure, though, it was network degradation. The solution is to deploy redundant replicas in different availability zones (and/or regions, if you can). Reddit unfortunately wasn't built for that. This isn't really any different from an on-premise application. An availability zone by definition implies "shared network hardware". Using multiple is what you do when you want redundancy.

snewman 16y ago
How do you know the issue was network degradation? Is this written up somewhere?
- parasubvert 16y ago
  The original Reddit blog post indicates there were latency problems initially. It's not clear what caused followon problems, but the latency may have triggered a bad condition for their replication.