How Swarm Responds to Disk Changes

Note

Swarm requires control of all volumes (disk.volumes = all) to support hot plugging.

I/O errors are recorded in the log if the Health Processor is actively scanning a disk when it is removed. These errors are expected and do not indicate a problem.
When a disk is removed, volume recovery (FVR) and erasure coding recovery (ECR) are both triggered, which includes creating new replicas or erasure set segments for objects stored on that disk.
Both recovery processes stop if a disk is inserted in the same node or a different node in the cluster. There is a temporary state of over-replication because the returned volume has replicas or segments already recreated elsewhere. In time, the excess replicas or segments are deleted.
Swarm recognizes, formats, and mounts a disk as a new volume if a non-Swarm disk is inserted in a node.
A Swarm-formatted disk continues to function as a volume without loss of data if inserted, either into the same node or into a different node.
A volume remains retired if a previously retired Swarm-formatted disk is inserted. No manual configuration or intervention is required.
Messages display in logs and in the Swarm Admin Console to indicate a disk was inserted or removed.
Wait 2 minutes between disk insertions to guarantee new disks are evenly distributed across multiple nodes running on the chassis if inserting multiple disks into the same server chassis.

Caution

When adding or relocating volumes to a node, verify the node has enough RAM to handle them, else the node may be unable to mount some of the volumes.

Warning

Do not move Swarm disks between disk array controller types after they are formatted by Swarm. Each controller reports available disk space to Swarm matched with the controller. For example, many controllers claim the last section of the disk, reducing the total available space. The new controller may claim additional disk space not reported to Swarm, so Swarm may attempt to write data to non-existing space, generating I/O errors if disks are switch with another controller.