The Build

10:22

Amazon’s New I/O Offerings

1 August 2012

Amazon has introduced a couple of new I/O-related offerings in AWS, both aimed at addressing the notoriously poor I/O performance of EBS.

The first is the EC2 High I/O Quadruple Extra Large Instance. This is a standard Quad XL instance with two 1TB SSD-backed volumes directly attached to the instance. Although Amazon does not quote I/O performance on this configuration, it should be quite speedy… under good conditions.

Before you race to deploy your database on this configuration, howver, remember:

The next product offering is Provisioned IOPS on EBS. This allows you to guarantee a certain number of I/O operations per second, up to 1,000 IOP/s. This should go a long way towards reducing the uncertainty around EBS, but it also comes with some caveats:

So, these products are far from useless, but they are incremental, not revolutionary.

Marti Raudsepp at 14:30, 1 August 2012:

> That’s about 1/5th the speed of a 7200 RPM SATA drive

That’s somewhat misleading. It’s correct when measuring sequential throughput only (depending on density and offset of the drive). But in a random access workload, 7200RPM can only deliver ~120 IOPS, so that’s 1/8 of what Amazon offers.

Xof at 14:35, 1 August 2012:

Well, I’d argue that it is still a fair comparison. Amazon only guarantees the 1,000 IOP/s if you keep the channel to the EBS server saturated. That’s much less likely with random I/O than sequential I/O, and Amazon does not publish latency numbers, nor do they guarantee any particular latency characteristics.

And, of course, if you got 1,000 IOP/s out of a modern SSD, you’d send it back.

Alex at 19:32, 1 August 2012:

the High I/O Instances disks are not that ephemeral since they survive to a reboot of the instance, and amazon gives you sometime if they force you to shutdown your server. i’m not saying it’s the best solution in the word but it’s a little better than the ephemeral storage on the other instances…

Xof at 19:35, 1 August 2012:

Well, “ephemeral” is Amazon’s term, not mine; they are *exactly* like the ephemeral storage on all instances. They survive reboots, but they do not survive beyond the particular instance, *and* they are not guaranteed to persist if Amazon migrates your instance to a new physical machine, which can happen all the time. You simply must assume they could vanish at any moment.