Script to run esxcli unmap on all datastores attached to an ESXi host

It’s a good idea to periodically run the UNMAP command on all your thin-provisioned LUNs. This allows the storage system to reclaim deleted blocks. (What is SCSI UNMAP?)

The format of the command is:

esxcli storage vmfs unmap -l <volume_label>

1	esxcli storage vmfs unmap -l <volume_label>

I wanted to make a script to run this on all attached datastores so here’s what I came up with:

#!/bin/sh
for datastore in `esxcli storage filesystem list | grep "VMDATA" | awk -F " " '{print $2}'`; do
  echo "Performing UNMAP on $datastore ..."
  esxcli storage vmfs unmap -l $datastore
done

#!/bin/sh

for datastore in `esxcli storage filesystem list | grep "VMDATA" | awk -F " " '{print $2}'`; do

echo "Performing UNMAP on $datastore ..."

esxcli storage vmfs unmap -l $datastore

done

The esxcli storage filesystem list command outputs a list of datastores attached to the system. The second column is what I am interested in, so that’s what awk takes care for me. I don’t want to target any local datastores, so I use grep to filter out the ones I am interested in.

Next step would be to add this to a cron job. Got to follow the instructions here, it looks like.