What's the difference between general purpose, 5IOPS, 10IOPS, and custom IOPS?

General purpose has burstable IOPS up to a cap. 5IOPS/GB and 10IOPS/GB provide guaranteed per-GB IOPS — useful when workload performance must be predictable. Custom IOPS lets you specify an exact IOPS number independent of size, useful when your workload needs high IOPS on a smaller volume. The cost increases with the guarantee level.

Can I resize a volume online?

Yes for size increases — the volume capacity can be expanded while attached and in use. Filesystem expansion (resize2fs, xfs_growfs) inside the guest is required to make the new space usable. Shrinking volumes is not supported online; you'd have to copy data to a new smaller volume and detach the old one.

IBM Block Storage Config Builder

StorageIBM Cloud

Build VPC block storage volume configurations with IOPS profiles, encryption, and snapshot policies.

Last verified: May 2026

IBM Cloud VPC Block Storage Configuration

Build VPC block storage volume configurations with IOPS profiles, encryption, snapshot policies, and backup strategies.

Required Fields

volumesvolumes[0].namevolumes[0].profilevolumes[0].capacity

{
  "volumes": [
    {
      "name": "prod-db-data",
      "zone": "us-south-1",
      "profile": "custom",
      "capacity": 500,
      "iops": 6000,
      "resourceGroup": "prod-resources",
      "encryption": {
        "type": "customer_managed",
        "keyProtectInstance": "key-protect-prod",
        "rootKeyId": "crk-block-vol-key"
      },
      "tags": ["env:production", "team:database"]
    },
    {
      "name": "prod-app-logs",
      "zone": "us-south-1",
      "profile": "general-purpose",
      "capacity": 250,
      "iops": 3000,
      "resourceGroup": "prod-resources",
      "encryption": {
        "type": "provider_managed"
      },
      "tags": ["env:production", "team:platform"]
    },
    {
      "name": "prod-high-perf",
      "zone": "us-south-2",
      "profile": "10iops-tier",
      "capacity": 1000,
      "iops": 10000,
      "resourceGroup": "prod-resources",
      "encryption": {
        "type": "provider_managed"
      }
    }
  ],
  "snapshotPolicies": [
    {
      "name": "daily-snapshot-policy",
      "volumes": ["prod-db-data"],
      "schedule": {
        "frequency": "daily",
        "hour": 2,
        "minute": 0,
        "timezone": "UTC"
      },
      "retentionCount": 7
    }
  ],
  "backupPolicies": [
    {
      "name": "weekly-backup",
      "matchTags": ["env:production"],
      "schedule": {
        "frequency": "weekly",
        "dayOfWeek": "sunday"
      },
      "retentionDays": 30,
      "crossRegionCopy": {
        "enabled": true,
        "targetRegion": "us-east"
      }
    }
  ]
}

Generated Output

Output will appear here...

See It in Action

Your team's database server has been on a 500 GB general-purpose volume that's been hitting its IOPS cap during peak hours, causing query latency. You analyze a week of metrics and find peak IOPS demand of ~3,000. Sizing a custom-IOPS volume at 3,500 IOPS for the same 500 GB capacity costs about 30% more than general-purpose but eliminates the contention. The latency p99 drops in half.

What This Tool Does

IBM Cloud VPC Block Storage volumes attach to virtual server instances as persistent disks with configurable IOPS profiles (5 IOPS/GB, 10 IOPS/GB, custom) and encryption options. The Block Storage Config Builder produces volume specs including profile, size, encryption, and snapshot schedules. Output is `ibm_is_volume` Terraform-ready with associated snapshot policy resources.

Technical Details

The builder collects volume name, zone, profile (general-purpose, 5iops-tier, 10iops-tier, custom), capacity, encryption configuration (provider-managed, Key Protect, HPCS), and snapshot policy. It validates the profile-capacity combination against IBM's published limits and emits an `ibm_is_volume` Terraform resource plus `ibm_is_snapshot_policy` resources if scheduled snapshots are configured.

Common Use Cases

1Provisioning a high-IOPS data volume for a database workload that needs predictable storage performance.
2Configuring a snapshot schedule for a critical volume so point-in-time recovery is automatic.
3Sizing a volume with custom IOPS for a workload whose performance needs don't fit the standard tiers.
4Encrypting a volume with a Key Protect-managed key so the encryption key lifecycle is auditable.

Common Questions

What's the difference between general purpose, 5IOPS, 10IOPS, and custom IOPS?: General purpose has burstable IOPS up to a cap. 5IOPS/GB and 10IOPS/GB provide guaranteed per-GB IOPS — useful when workload performance must be predictable. Custom IOPS lets you specify an exact IOPS number independent of size, useful when your workload needs high IOPS on a smaller volume. The cost increases with the guarantee level.
Can I resize a volume online?: Yes for size increases — the volume capacity can be expanded while attached and in use. Filesystem expansion (resize2fs, xfs_growfs) inside the guest is required to make the new space usable. Shrinking volumes is not supported online; you'd have to copy data to a new smaller volume and detach the old one.

Expert Tips

TIP

Pick IOPS based on observed workload, not nameplate maximums. Most databases are bound by latency and throughput more than IOPS — checking your actual workload's IOPS for a few days beats guessing.

TIP

Always schedule snapshots for production volumes. A snapshot of a quiesced volume is the cheapest disaster recovery insurance you can buy, and the cost of stored snapshots is dramatically lower than the cost of a unrecoverable database.

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