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Can Cloudstor volumes be resized?

Article ID: KB000608

In Docker for AWS, Cloudstor has two backing options:

  • Relocatable data volumes that are backed by EBS
  • Shared data volumes that are backed by EFS

Shared Cloudstor Volumes

Shared volumes are backed by EFS, and there is no concept of capacity or expansion because it just scales up to however much capacity is needed. 

Relocatable Cloudstor Volumes

When using relocatable volumes, there is a requirement to specify capacity so resizing comes into the picture. To expand the AWS volume:

  1. nsenter into the Docker host to figure out the device name
  2. Expand the partition using resize2fs

Note that since it uses ext4 FS, the resizing can be done in online mode (i.e. without having to dismount). 

Considerations

EFS backed shared volumes can be much simpler with no resizing, etc. to consider. Also, mapping volumes is really fast across availability zones. The only drawback is shared volumes have low iops and throughput which makes certain workloads unsuitable.