Drive or shelf evacuation is a resource-intensive, background data mobility process within the Purity operating system. When an Implementation Engineer issues an evacuation command via the CLI (e.g., puredrive evacuate) or the GUI, the array begins transparently reading data blocks from the targeted DirectFlash Modules, recalculating parity, and destaging those blocks onto the remaining free capacity in the chassis or a connected swing shelf.

According to strict Pure Storage Implementation guidelines, only one evacuation process can be actively running on a FlashArray at any given time . The system architecture does not support queuing multiple, simultaneous drive or shelf evacuations, nor does it allow an administrator to arbitrarily inject new drives into an active evacuation job.

If an engineer attempts to issue a second evacuation command while the first is still running, the Purity operating system will immediately reject the command and return an error stating that an evacuation is already in progress. While it is technically possible to cancel an evacuation, doing so forces the array to halt its progress and leaves the data fragmented across the old and new drives, wasting time. The only supported and safe method is to let the current evacuation reach 100% completion, physically remove the evacuated drives, and then initiate a completely separate, new evacuation job for the second data pack.