Google, Amazon, and Azure appear to have shaped their clouds after their internal needs first. This has lead to peculiarities in their pricing and feature sets. Amazon, for example, is fine with scaling out to an extreme degree, and so their storage options, particularly their provisioned IOPS options, are rather expensive. Their network and storage infrastructure is likely the oldest and with the lowest turnover rate, so they're the most expensive to get performant storage on.
Google probably has the highest server turnover rate, and my wager is that they recently switched to new SSDs to reduce failure rates in their datacenters. My guess is that their compute servers are now swimming in excess IOPS, and so they are clearly the cheapest if you want very fast storage. This reminds me of Facebook purchasing massive quantities of SSDs for their own datacenters.
Microsoft has very peculiar needs. Azure grew out of servicing internal Microsoft IT needs first, so it is stuck with some quirks. You don't provision IOPS, you create disks, which you attach to VMs. There are no IOPS tunable options for their PaaS, only IaaS VMs. They use software RAID (Linux or Windows) to turn multiple disks into higher speed storage. Their storage backend can only be described as weird[1], because whatever you think the actual disk layout looks like from your VM's perspective, it doesn't look anything like that on the storage layer. They partition data into chunks (disks) which get written to a distributed, log-structured file system on JBODs. Every 1GB extant is made immutable once full, and they use erasure encoding to distribute the data such that they can sustain 2 failures with only 33% disk overhead. The result is that writes are cheap (almost all writes are sequential) and the backend does a bunch of compute work to make reads fast (with caching of metadata and the erasure encoding, I'm guessing).
Google probably has the highest server turnover rate, and my wager is that they recently switched to new SSDs to reduce failure rates in their datacenters. My guess is that their compute servers are now swimming in excess IOPS, and so they are clearly the cheapest if you want very fast storage. This reminds me of Facebook purchasing massive quantities of SSDs for their own datacenters.
Microsoft has very peculiar needs. Azure grew out of servicing internal Microsoft IT needs first, so it is stuck with some quirks. You don't provision IOPS, you create disks, which you attach to VMs. There are no IOPS tunable options for their PaaS, only IaaS VMs. They use software RAID (Linux or Windows) to turn multiple disks into higher speed storage. Their storage backend can only be described as weird[1], because whatever you think the actual disk layout looks like from your VM's perspective, it doesn't look anything like that on the storage layer. They partition data into chunks (disks) which get written to a distributed, log-structured file system on JBODs. Every 1GB extant is made immutable once full, and they use erasure encoding to distribute the data such that they can sustain 2 failures with only 33% disk overhead. The result is that writes are cheap (almost all writes are sequential) and the backend does a bunch of compute work to make reads fast (with caching of metadata and the erasure encoding, I'm guessing).
[1] - http://snia.org/sites/default/files2/SDC2013/presentations/G...
[2] - http://research.microsoft.com/pubs/179583/LRC12-cheng%20webp...