roachtest: cluster_creation failed

roachtest.cluster_creation [failed](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/21275231?buildTab=log) with [artifacts](https://teamcity.cockroachdb.com/buildConfiguration/Cockroach_Nightlies_RoachtestNightlyAwsBazel/21275231?buildTab=artifacts#/kv95/enc=false/nodes=3/cpu=32/seq) on release-26.1.2-rc @ [6539acc10020630b6fb61f5e1e8aa06ae7820f8e](https://github.com/cockroachdb/cockroach/commits/6539acc10020630b6fb61f5e1e8aa06ae7820f8e):

```
test kv95/enc=false/nodes=3/cpu=32/seq failed: (test_runner.go:991).func4: in provider: aws: failed to run: aws ec2 run-instances --associate-public-ip-address --count 1 --instance-type c7gd.8xlarge --image-id ami-05983a09f7dc1c18f --key-name teamcity-runner-M9q0zLoNYHarPvCe106tkkgyACA= --region us-east-2 --security-group-ids sg-04d72b57e29d671f1 --subnet-id subnet-0258dc9d1b6473d84 --tag-specifications ResourceType=instance,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=release-26-1-2-rc},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-21275231-1773987689-51-n4cpu32},{Key=lifetime,Value=12h0m0s},{Key=arch,Value=arm64},{Key=created,Value=2026-03-20T07:15:58Z},{Key=Name,Value=teamcity-21275231-1773987689-51-n4cpu32-0002},{Key=Cluster,Value=teamcity-21275231-1773987689-51-n4cpu32},{Key=spot,Value=true}] ResourceType=volume,Tags=[{Key=usage,Value=roachtest},{Key=roachtest-branch,Value=release-26-1-2-rc},{Key=roachprod,Value=true},{Key=cluster,Value=teamcity-21275231-1773987689-51-n4cpu32},{Key=lifetime,Value=12h0m0s},{Key=arch,Value=arm64},{Key=created,Value=2026-03-20T07:15:58Z},{Key=Name,Value=teamcity-21275231-1773987689-51-n4cpu32-0002},{Key=Cluster,Value=teamcity-21275231-1773987689-51-n4cpu32},{Key=spot,Value=true}] --user-data file:///tmp/aws-startup-script3465184757 --iam-instance-profile Name=roachprod-testing --block-device-mapping file:///tmp/aws-block-device-mapping2693298440 --instance-market-options MarketType=spot,SpotOptions={SpotInstanceType=one-time,InstanceInterruptionBehavior=terminate} --output json: stderr:
An error occurred (MaxIOPSLimitExceeded) when calling the RunInstances operation: You have exceeded your maximum io2 IOPS limit of 100000 IOPS in this region. Please contact AWS Support to request an Elastic Block Store service limit increase.: exit status 254 [owner=test-eng]
```

Parameters:
- MetamorphicFilesystem=ext4
- MetamorphicVolumeType=io2
- cloud=aws
- coverageBuild=false
- cpu=32
- diskCount=0
- runtimeAssertionsBuild=false
Help

See: [roachtest README](https://github.com/cockroachdb/cockroach/blob/master/pkg/cmd/roachtest/README.md)

See: [How To Investigate \(internal\)](https://cockroachlabs.atlassian.net/l/c/SSSBr8c7)

/cc @cockroachdb/test-eng

[This test on roachdash](https://roachdash.crdb.dev/?filter=status:open%20t:.*cluster_creation.*&sort=title+created&display=lastcommented+project) | [Improve this report!](https://github.com/cockroachdb/cockroach/tree/master/pkg/cmd/bazci/githubpost/issues)

Jira issue: CRDB-61818

Start with the linked TeamCity failure and artifacts, then read pkg/cmd/roachtest/README.md and the AWS cluster-creation path referenced by the report. Confirm how the io2 IOPS limit causes the RunInstances failure and review the 250-comment thread for the current diagnosis. Done means the cluster_creation test no longer fails from this regional limit or the issue documents a confirmed operational resolution.

Written by the indexing model from the issue text.