Cluster Deployment Options

The following options can be set when creating a cluster. This applies to both plain Linux and Kubernetes deployments. Most cannot be changed later on, so careful planning is recommended.

`--enable-node-affinity`

As long as a node is not full (out of capacity), the first chunk of data is always stored on the local node (the node to which the volume is attached). This reduces network traffic and latency, particularly for reads, but may lead to an uneven distribution of capacity within the cluster. Generally, using node affinity accelerates reads, but leads to higher variability in performance across nodes in the cluster. It is recommended particularly for 1+1 EC schemas.

`--data-chunks-per-stripe, --parity-chunks-per-stripe`

Those two parameters together make up the erasure coding schema of the cluster (e.g., 1+1, 2+2, 4+2). The schema is set once at cluster creation and applies to all volumes in the cluster. It cannot be configured per volume.

`--cap-warn, --cap-crit`

Warning and critical limits for overall cluster utilization. If the warning limit is exceeded, warnings will be issued in the event log. If the "critical" limit is exceeded, the cluster will be placed into read-only mode. For large clusters, a 99% "critical" limit is OK. For small clusters (less than 50 TB), 97% is better.

`--prov-cap-warn, --prov-cap-crit`

Warning and critical limits for over-provisioning. Exceeding these limits will cause entries in the cluster log. If the critical limit is exceeded, new volumes cannot be provisioned and volumes cannot be enlarged. A limit of 500% is typical.

`--log-del-interval`

Number of days for which logs are retained. Log storage can grow significantly, and it is recommended not to keep logs for longer than one week. This is only relevant if the observability stack is deployed.

`--metrics-retention-period`

Number of days for which the I/O statistics and other metrics are retained. The amount of data per day is significant, so retention should typically be limited to a few days or a week.

`--contact-point`

This is a webhook endpoint for alerting on critical events such as storage nodes becoming unreachable. This is only relevant if the observability stack is deployed.

`--fabric`

Choose tcp, rdma, or both. If both fabrics are chosen, volumes can connect to the cluster using either option (defined per volume or storage class), but the cluster internally uses rdma.

`--qpair-count`

The default number of queue pairs (sockets) per volume used within the storage cluster. More queue pairs per volume increase concurrency and volume performance, but require more server resources (RAM, CPU) and thus limit the total number of volumes per storage node. The default is 32. For a few very performant volumes, increase the amount. For a large number of less performant volumes, decrease it. The number of queue pairs per client (initiator) connection is controlled separately via --client-qpair-count (default 3). The host requires at least one core per queue pair.

`--enable-failure-domain`

Enables failure-domain anti-affinity for the cluster. Each storage node must then be added with a --failure-domain tag (rack, cabinet, or availability zone), and data, journal copies, and failover paths are spread across distinct failure domains. This option is deploy-time only: a cluster cannot be upgraded into the feature, it must be redeployed. See Failure Domains.

`--use-backup`

Path to a JSON file with S3 or S3-compatible (MinIO) backup configuration. This enables snapshot-based backup and recovery for the cluster.

Example: backup-config.json (AWS S3)

{
  "access_key_id": "<AWS_ACCESS_KEY>",
  "secret_access_key": "<AWS_SECRET_KEY>",
  "bucket_name": "simplyblock-backups"
}

Example: backup-config.json (MinIO / S3-compatible)

{
  "access_key_id": "<MINIO_ACCESS_KEY>",
  "secret_access_key": "<MINIO_SECRET_KEY>",
  "bucket_name": "simplyblock-backups",
  "local_endpoint": "http://minio.example.com:9000"
}

Key	Description	Required
`access_key_id`	S3 access key ID.	Yes
`secret_access_key`	S3 secret access key.	Yes
`bucket_name`	S3 bucket name. Defaults to `simplyblock-backup-<CLUSTER_ID>` if omitted.	No
`local_endpoint`	Custom S3 endpoint URL for MinIO or other S3-compatible storage.	No
`with_compression`	Enable compression for backup data. Default: `false`.	No
`snapshot_backups`	Enable snapshot-based incremental backups. Default: `true`.	No

For more information on backup operations, see Backup and Recovery.

`--name`

A human-readable name for the cluster.