The other day I decided to switch out my disk that I was using for VSAN caching. I was doing some testing with an NVME, but now had to back it down to a SAS SSD. The disk I used had been used previously in a different system, so it had a foreign configuration that I had to remove.
- Best practice would be to work on one host at a time. Put the first host in maintenance mode, and choose to “Ensure Availability”.
- After the host is in maintenance mode, click on your cluster then click “Configure” tab, and then click “Disk Management“.
- Click on the disk group that you want to remove and then click the “Remove the disk group” button.
- You will get another data migration question. I choose “Ensure data accessibility from other hosts“. Click “Yes“.
- Wait for the disk group to be removed from the host. When complete, reboot your host. When prompted during the boot process, press “Ctrl-R” to get to the raid configuration menu.
- Press “Ctrl-P” or “Ctrl-N” to switch pages. One of the pages should show your disks and the slots they are in. We have a problem here. The only option for my 400GB SSD is to erase the disk because it has the state of “Foreign“.
- Switch pages to the “Virtual Drive Management” page and then on the Cisco 12G SAS Modular Raid press “F2“. This will give a menu; select “Foreign Config” and then “Clear“.
- This will clear out your configuration so please make sure that you have thought things through. If you are OK with the possibility of data loss, click “Yes“.
- Now we are getting somewhere. The disk now shows UG (Unconfigured Good).
- Highlight the disk and then press “F2“. From the menu click “Make JBOD“.
- DATA ON DISKS WILL BE DELETED so make sure you want to do this. Click “Yes” to proceed.
- All looks good. Escape out and exit the application. Reboot your host when done.
- My new 400GB disk shows up in VMware now.
- Now click on your cluster, then click the “Configure” tab and then click “Disk Management“. Click on the host that you removed the disk from earlier and then choose “Add disk group” button. Choose your cache disk and your capacity disks and you are ready to go. Take your host out of maintenance mode and repeat steps on each host.