Last month Amazon reduced by 50% prices for EBS storage. This, combined with shrinking EBS root volume size and moving /tmp to instance storage allowed me to reduce EBS related costs behind Difio by around 50%. Following are the real figures from my AWS Bill.
EBS costs for Difio were gradually rising up with every new node added to the cluster and increased package processing (resulting in more I/O):
- November 2013 - $7.38
- December 2013 - $10.55
- January 2014 - $11.97
January 2014:
EBS
$0.095 per GB-Month of snapshot data stored 9.052 GB-Mo $0.86
$0.10 per GB-month of provisioned storage 101.656 GB-Mo $10.17
$0.10 per 1 million I/O requests 9,405,243 IOs $0.94
Total: $11.97
In February there was one new system added to process additional requests (cluster nodes run as spot instances) and an increased number of temporary instances (although I haven't counted them) while I was restructuring AMI internals to accommodate the open source version of Difio. My assumption (based on historical data) is this would have driven the costs up in the region of $15 per month only for EBS.
After implementing the stated minimal improvements and having Amazon reduced the prices by half the bill looks like this:
February 2014:
EBS
$0.095 per GB-Month of snapshot data stored 8.668 GB-Mo $0.82
$0.05 per GB-month of provisioned storage 58.012 GB-Mo $2.90
$0.05 per 1 million I/O requests 5,704,482 IOs $0.29
Total: $4.01
Explanation
Snapshot data stored is the volume of snapshots (AMIs, backups, etc) which I have. This is fairly constant.
Provisioned storage is the volume of EBS storage provisioned for running instances (e.g. root file system, data partitions, etc.). This was reduced mainly because of shrinking the root volumes. (Previously I've used larger root volumes for a bigger /tmp).
I/O requests is the number of I/O requests associated with your EBS volumes. As far as I understand Amazon doesn't charge for I/O related to ephemeral storage. Moving /tmp from EBS to instance storage is the reason this was reduced roughly by half.
Where To Next
I've reduced the root volumes back to the 8GB defaults but this has still room for improvement b/c the AMI is quite minimal. This will bring the largest improvements. Another thing is the still relatively high I/O rate that touches EBS volumes. I haven't investigated where this comes from though.
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