Error not enough volumes named foo (1) to run 2 processes

[mrkishi]

Volumes can’t be attached to multiple instances.

As per the docs:

Volumes are bound to both apps and regions. A volume is directly associated with only one app and exists in only one region.

And kurt around here:

@kurt

Volumes can only be used by a single VM at a time (they’re basically just local disks that stick around between reboots).