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Cloud · head to head

Lambda (AWS Serverless) vs Rook

Lambda (AWS Serverless) logo

Lambda (AWS Serverless)

Cloud

Run code without thinking about servers

From
Free
Rated
-
Full reviewWebsite
Rook logo

Rook

Cloud

Kubernetes operator that deploys and manages Ceph storage clusters

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Lambda (AWS Serverless) billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does; Rook rook automates Ceph but does not abstract it, so an incident still demands Ceph expertise, and organisations without it end up hiring consultants at exactly the wrong moment.
  • They diverge on capability: Lambda (AWS Serverless) covers Function-as-a-Service, Rook covers Ceph operator.
  • Prices and features above were last checked on 1 September 2026.

Where they differ

Only the attributes on which Lambda (AWS Serverless) and Rook actually diverge.

Attributes where Lambda (AWS Serverless) and Rook differ
AttributeLambda (AWS Serverless)Rook
Pricing modelusage-basedOpen source, no licence fee
PlatformsWeb, ApiLinux, Kubernetes
Founded2014Unknown

Identical on both: starting price (Free), free tier (Yes), user rating (Not yet rated), category (Cloud).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Lambda (AWS Serverless)

  • Function-as-a-Service
  • Event-driven execution
  • Auto-scaling
  • Pay-per-use
  • Multiple languages
  • Concurrency limits
  • Dead Letter Queues
  • Environment variables

Only in Rook

  • Ceph operator
  • Block, file and object
  • Erasure coding
  • CSI driver
  • Automated upgrades
  • Multi-cluster mirroring

What people use each for

The jobs each tool is most often brought in to do.

Lambda (AWS Serverless)

  • Event-driven functions without managing serversnot Rook
  • API backends behind API Gatewaynot Rook
  • Processing S3, DynamoDB, SQS and Kinesis eventsnot Rook
  • Scheduled jobs without a always-on instancenot Rook
  • Edge compute through Lambda@Edgenot Rook

Rook

  • An on-premises Kubernetes platform needing block, shared filesystem and S3 storage without buying three productsnot Lambda (AWS Serverless)
  • A team that already runs Ceph and wants its lifecycle managed declaratively inside Kubernetesnot Lambda (AWS Serverless)
  • A large cluster where three-way replication overhead is unaffordable and erasure coding is requirednot Lambda (AWS Serverless)
  • An organisation building a private cloud that cannot use managed cloud storage services for residency reasonsnot Lambda (AWS Serverless)

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Lambda (AWS Serverless)

  • Billed on two axes at once, $0.20 per million requests plus $0.0000166667 per GB-second of duration, so memory settings change the bill as much as traffic does
  • Provisioned concurrency, used to avoid cold starts, is charged separately at $0.0000041667 per GB-second whether or not the function runs
  • Ephemeral storage beyond the included 512 MB is metered
  • Lambda@Edge costs $0.60 per million requests, three times the standard request rate
  • VPC use and cross-region data transfer carry EC2 charges on top

Rook

  • Rook automates Ceph but does not abstract it, so an incident still demands Ceph expertise, and organisations without it end up hiring consultants at exactly the wrong moment.
  • There is no vendor and no SLA; the realistic commercial support routes are IBM Red Hat OpenShift Data Foundation or an independent Ceph consultancy, both of which change the cost picture entirely.
  • Ceph is resource hungry, needing substantial memory and dedicated disks per OSD, so the hardware cost of a properly sized cluster is often underestimated.
  • Recovery and rebalancing after a disk or node failure generates heavy background input and output that can degrade application performance for hours, which surprises teams sizing for steady state.
  • Minimum viable clusters require several nodes with several disks each, so it is impractical at small scale and the entry hardware cost exceeds simpler alternatives.

Pricing, plan by plan

Lambda (AWS Serverless)

Free
  • Free TierFree
    • 1M free requests/month
    • 400,000 GB-seconds/month
    • Always free

Rook

Free
  • RookFree
    • Apache 2.0 licensed, no licence fee
    • Graduated CNCF project
    • Community support via GitHub and Slack only

Which should you pick?

Choose Lambda (AWS Serverless) if

  • You need function-as-a-service.
  • You want to start without paying.
  • You work on Web, Api.
  • You also want event-driven execution.
Lambda (AWS Serverless) review

Choose Rook if

  • You need ceph operator.
  • You want to start without paying.
  • You work on Linux, Kubernetes.
  • You also want block, file and object.
Rook review

Questions people ask

Is Lambda (AWS Serverless) or Rook better?
Neither clearly leads. Lambda (AWS Serverless) starts at Free and Rook at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Lambda (AWS Serverless) or Rook?
Lambda (AWS Serverless) starts at Free and Rook at Free.
Does Lambda (AWS Serverless) or Rook run on more platforms?
Lambda (AWS Serverless) runs on Web, Api. Rook runs on Linux, Kubernetes.
Can I use Lambda (AWS Serverless) for free?
Both have a free tier, so you can try either at no cost before committing.
What is Lambda (AWS Serverless) best used for?
Lambda (AWS Serverless) is most often used for event-driven functions without managing servers, api backends behind api gateway, processing s3, dynamodb, sqs and kinesis events, scheduled jobs without a always-on instance. Of those, event-driven functions without managing servers and api backends behind api gateway are not what Rook is typically brought in for.
What can Lambda (AWS Serverless) do that Rook cannot?
Lambda (AWS Serverless) covers Function-as-a-Service, Event-driven execution, Auto-scaling, Pay-per-use. Rook covers Ceph operator, Block, file and object, Erasure coding, CSI driver.

Answered from the vendors’ own pages

Lambda (AWS Serverless): Is there a free tier for AWS Lambda?

Yes. AWS Lambda offers a free tier including 1 million requests per month, 400,000 GB-seconds per month, and 100 GB monthly response streaming.

Source
Rook: Who supports it in production?

Nobody by default. IBM sells Red Hat OpenShift Data Foundation, which is supported Rook and Ceph, and independent consultancies sell Ceph support. Decide this before deployment.

Lambda (AWS Serverless): How is AWS Lambda charged?

Lambda charges $0.20 per million requests. Duration charges are $0.0000166667 per GB-second for x86 (up to 6 billion GB-seconds/month in US East Ohio with tiered pricing). Ephemeral storage over the included 512 MB costs $0.0000000309 per GB-second. Provisioned Concurrency costs $0.0000041667 per GB-second with a 5-minute minimum.

Source
Rook: Does it need Ceph knowledge?

Yes. Rook handles deployment and routine operations, but troubleshooting a degraded cluster is a Ceph skill and there is no way around it.

Lambda (AWS Serverless): What are Lambda Durable Functions pricing?

Lambda Durable Functions include operations at $8.00 per million (start execution, steps, waits). Data written costs $0.25 per GB. Data retention is $0.15 per GB-month with configurable 1-90 day retention (default 14 days).

Source
Rook: Can it replace an object storage appliance?

Functionally yes, through the RADOS gateway, but you take on the operations that an appliance vendor would otherwise carry.

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