The Clean Exit: How to Safely Remove Storage Devices from ESXi | Lazy Admin Blog

Posted on November 21, 2015 Updated on March 23, 2026

In the world of storage, “unpresenting” a LUN is more than just a right-click. If you don’t follow the proper decommissioning workflow, ESXi will keep trying to talk to a ghost device, leading to host instability and long boot times.

Follow this definitive checklist and procedure to ensure your environment stays clean and APD-free.

The “Safe-to-Remove” Checklist

Before you even touch the unmount button, verify these 7 critical points:

1. Evacuate Data: Move or unregister all VMs, snapshots, templates, and ISO images from the datastore.
2. HA Heartbeats: Ensure the datastore is NOT being used for vSphere HA heartbeats.
3. No Clusters: Remove the datastore from any Datastore Clusters or Storage DRS management.
4. Coredump: Confirm the LUN isn’t configured as a diagnostic coredump partition.
5. SIOC: Disable Storage I/O Control (SIOC) for the datastore.
6. RDMs: If the LUN is an Raw Device Mapping, remove the RDM from the VM settings (select “Delete from disk” to kill the mapping file).
7. Scratch Location: Ensure the host isn’t using this LUN for its persistent scratch partition.

Pro Tip: Check Scratch Location via PowerCLI

Use this script to verify your scratch config across a cluster:

$cluster = "YourClusterName"
foreach ($esx in Get-Cluster $cluster | Get-VMHost) {
    Get-VMHostAdvancedConfiguration -VMHost $esx -Name "ScratchConfig.ConfiguredScratchLocation"
}

Step 1: Identify your NAA ID

You need the unique Network Address Authority (NAA) ID to ensure you are pulling the right plug.

• Via GUI: Check the Properties window of the datastore.
• Via CLI: Run esxcli storage vmfs extent list

Step 2: The Unmount & Detach Workflow

1. Unmount the File System

In the Configuration tab > Storage, right-click the datastore and select Unmount. If you are doing this for multiple hosts, use the Datastores view (Ctrl+Shift+D) to unmount from the entire cluster at once.

2. Detach the Device (The Most Important Step)

Unmounting removes the “logical” access, but Detaching tells the kernel to stop looking for the “physical” device.

• Switch to the Devices view.
• Right-click the NAA ID and select Detach.
• The state should now show as Unmounted.

Note: Detaching is a per-host operation. You must perform this on every host that has visibility to the LUN to avoid APD states.

Step 3: Cleanup the SAN & Host

Once the state is “Unmounted” across all hosts, you can safely unmap/unpresent the LUN from your SAN array.

Permanent Decommissioning

To prevent “ghost” entries from appearing in your detached list, run these commands on the host:

1. List detached devices: esxcli storage core device detached list
2. Remove the configuration permanently: esxcli storage core device detached remove -d <NAA_ID>