You must replace a flash caching device if you detect a failure or when there is an upgrade. Removing the cache device removes the entire disk group from the vSAN cluster.

Caution: If you decommission the flash caching device without removing it from vSAN first, vSAN uses smaller amount of cache than expected. As a result, the cluster performance becomes degraded.

When you replace a flash caching device, the virtual machines on the disk group become inaccessible and the components on the group are marked as degraded. See A Flash Caching Device Is Not Accessible in a vSAN Cluster.

Prerequisites

  • Verify that the storage controllers on the hosts are configured in passthrough mode and support the hot-plug feature.

    If the storage controllers are configured in RAID 0 mode, see the vendor documentation for information about adding and removing devices.

  • If you upgrade the flash caching device, verify the following requirements:
    • If you upgrade the flash caching device, verify that the cluster contains enough space to migrate the data from the disk group that is associated with the flash device.
    • Place the host in maintenance mode.

Procedure

  1. Navigate to the vSAN cluster.
  2. On the Configure tab, click Disk Management under vSAN.
  3. Select the entire disk group that contains the flash caching device that you want to remove. vSAN does not allow you to remove the cache disk. To remove the cache disk, you must remove the entire disk group.
  4. Click and click REMOVE.
  5. In the Remove Disk Group dialog box, select any of the following data migration mode to evacuate the data on the disks.
    • Full data migration - Transfers all the data available on the host to other hosts in the cluster.
    • Ensure accessibility - Transfers data available on the host to the other hosts in the cluster partially. During the data transfer, all virtual machines on the host remains accessible.
    • No data migration - There is no data transfer from the host. At this time, some objects might become inaccessible.
  6. Click GO TO PRE-CHECK to find the impact on the cluster if the object is removed or placed in maintenance mode.
  7. Click REMOVE to remove the disk group.

Results

vSAN removes the flash caching device along with the entire disk group from the cluster.

What to do next

  1. Add a new device to the host.

    The host automatically detects the device.

  2. If the host is unable to detect the device, perform a device rescan.