Cloud Cost Engineering and Open Source FinOps
Notes from the team building C3X. Cost estimation for Terraform, the economics of cloud infrastructure, and how to ship FinOps tooling without a SaaS gate.
Fargate task right-sizing cost: stop over-allocating vCPU and memory
Fargate bills for exactly the vCPU and memory you allocate to a task, so over-allocating is pure waste that scales with task count. Right-sizing tasks to real usage often cuts Fargate spend by 30 to 50 percent. Here is how to size tasks to what they actually use.
AWS Batch on Spot: cutting batch compute cost up to 90 percent
AWS Batch schedules containerized batch jobs across compute you configure, and because most batch work is interruption-tolerant, running it on Spot can cut compute cost by up to 90 percent. Here is how to configure Batch for Spot savings without losing jobs to interruptions.
S3 Glacier Instant Retrieval cost: cheap archive with fast access
S3 Glacier Instant Retrieval stores data at about $0.004 per GB, roughly a sixth of S3 Standard, while still giving millisecond access. Here is what it costs, where the retrieval fees bite, and when it beats Standard-IA and the slower Glacier tiers.
S3 replication cost explained: what CRR and SRR really bill
S3 replication looks like a checkbox but bills on four separate lines: destination storage, PUT requests, inter-region data transfer, and optional Replication Time Control. Here is how each is priced and how to keep replication from doubling your storage bill.
S3 versioning storage cost: why old versions inflate your bill
S3 versioning protects against overwrites and deletes, but every version is a full object billed at the full storage rate. Without lifecycle rules to expire noncurrent versions, a versioned bucket can store several times the data you think it does. Here is how to keep it in check.
S3 multipart upload cost: the incomplete uploads billing silently
S3 multipart upload is efficient for large files, but abandoned or failed uploads leave parts stored and billing forever, invisible in the normal object listing. Here is how the request and storage costs work, and the one lifecycle rule that stops the silent leak.
EBS io2 Block Express cost: when the fastest volume pays for itself
EBS io2 Block Express delivers up to 256,000 IOPS and 4,000 MB/s per volume at the same price as regular io2. Here is how the tiered IOPS pricing works, what a high-performance database volume actually costs, and when gp3 is the smarter buy.
EBS throughput vs IOPS cost: which one you are actually paying for
On gp3 you provision IOPS and throughput separately, and paying for the wrong one is a common waste. Here is how the two are priced, how to tell which your workload needs, and why a database and a log archive want opposite settings.
RDS storage autoscaling cost: convenient, but it only ratchets up
RDS storage autoscaling prevents out-of-space outages by growing your volume automatically, and the feature itself is free. The catch is that it never shrinks, so a one-time spike can leave you paying for oversized storage for the life of the instance. Here is how to use it without the ratchet.
RDS gp3 vs io1 storage cost: which database volume type to pick
RDS gp3 gives a free IOPS and throughput baseline for a flat per-GB price, while io1 charges separately for every provisioned IOPS. For most databases gp3 is dramatically cheaper. Here is the pricing, the break-even, and when io1 still earns its cost.
RDS reserved instances cost: how much they save and when to buy
RDS Reserved Instances cut the hourly rate of a database by up to about 40 percent for a one-year term and 60 percent for three years, in exchange for a commitment. Here is how the payment options compare, where the size-flexibility applies, and how to avoid over-committing.
Aurora Global Database cost: what cross-region replication really adds
Aurora Global Database gives sub-second cross-region replication and fast disaster recovery, but it bills replicated write I/O, storage in every region, secondary instances, and cross-region transfer. Here is the full cost breakdown and how to keep a global database from multiplying your bill.
DynamoDB GSI cost explained: the index that quietly doubles writes
A DynamoDB Global Secondary Index has its own throughput and storage, and every write to the base table that touches indexed attributes is also billed against the GSI. Here is how GSI cost works, why projections matter, and how a few indexes can double your write bill.
DynamoDB backup and restore cost: on-demand, PITR, and exports compared
DynamoDB offers on-demand backups, point-in-time recovery, and S3 exports, each priced differently. Here is what each costs per GB, when continuous backup is worth double the on-demand rate, and how restores and exports are billed.
DynamoDB DAX cost: is the in-memory cache worth it?
DynamoDB Accelerator (DAX) is a managed in-memory cache that can cut read latency to microseconds and read cost on hot data, but it runs on always-on nodes with a three-node minimum for production. Here is what DAX costs and the read volume where it starts to pay for itself.
Redshift RA3 vs DC2 cost: separating compute from storage
Redshift DC2 nodes bundle compute and fixed local storage, while RA3 nodes separate them and bill managed storage per GB. For growing datasets RA3 is usually cheaper; for small, compute-heavy clusters DC2 can still win. Here is the pricing and the crossover point.
Redshift concurrency scaling cost: the free credits and what runs over
Redshift concurrency scaling adds transient clusters to absorb query spikes, and it comes with a daily free credit that covers many workloads for nothing. Here is how the free tier works, what overflow costs, and how to keep concurrency scaling from becoming an uncapped bill.
Athena partitioning cost savings: pay for less scanned data
Athena charges $5 per terabyte scanned, so the whole cost game is scanning less. Partitioning, columnar formats, and compression can cut the data a query reads by 10 to 100 times. Here is how each lever works and how they stack to slash an Athena bill.
AWS Glue crawler cost: the minimum charges that add up
Glue crawlers keep your Data Catalog in sync with S3, but they bill per DPU-hour with a 10-minute minimum and a 2-DPU floor, so frequent crawls of many tables cost more than teams expect. Here is the pricing and how to crawl less to spend less.
EFS Infrequent Access cost: cutting file storage by 90 percent
EFS Standard costs $0.30 per GB-month, one of the priciest storage options on AWS, but its Infrequent Access tier drops to $0.016 per GB, a near-95-percent cut. Here is how EFS lifecycle management moves cold files automatically and where the access fees bite.
NAT Gateway vs NAT instance cost: when a self-managed box wins
A NAT Gateway costs about $0.045 per hour plus $0.045 per GB processed, while a NAT instance is just an EC2 box with no per-GB processing fee. For low traffic the instance can be far cheaper, but it trades money for operational risk. Here is the math.
VPC gateway vs interface endpoint cost: free vs per-hour PrivateLink
Gateway VPC endpoints for S3 and DynamoDB are completely free, while interface endpoints cost about $0.01 per hour per AZ plus $0.01 per GB. Knowing which services use which endpoint type, and how the fees stack across AZs, keeps PrivateLink affordable. Here is the breakdown.
CloudFront price classes cost: paying less by serving fewer regions
CloudFront price classes let you exclude the most expensive edge locations, trading global reach for a lower per-GB rate. Price Class 100 serves only North America and Europe at the cheapest rates. Here is how the classes change your bill.
Cross-AZ vs cross-region data transfer cost: the two hidden network taxes
Traffic between availability zones costs about $0.01 per GB each way, while traffic between regions runs roughly $0.02 per GB or more. Both are easy to trigger accidentally and both compound at scale. Here is how the two taxes differ and how to avoid them.