5 Replies Latest reply on Jun 6, 2019 1:52 PM by TheBobkin

    Maintain Cache tier on a vSAN Cluster

    SrVMwarer Novice

      Hi VMwarers!

      As I am learning vSAN101 wondering what is the professional methods to replace a SSD disk, surely if we have a Disk Group that contains a single SSD and we need to replace that SSD or it is just failed or about to fail, I've searched for answers but I wanted a professional answers from you the experts.

        • 1. Re: Maintain Cache tier on a vSAN Cluster
          TheBobkin Virtuoso
          VMware EmployeesvExpert

          Hello,

           

          If you remove a Capacity-tier SSD that is the only Capacity-tier device in this Disk-Group the Disk-Group goes away with it. With regard to how to replace it, this depends on a number of factors including:

          - Does the controller support hot-plug? (if not then don't).

          - Is there available space + FDs and/or a business requirement to maintain FTT during maintenance? If so then chose to remove the device with EA/FDM accordingly. (I wouldn't advise trying FDM off a device if it has issues).

           

          Bob

          • 2. Re: Maintain Cache tier on a vSAN Cluster
            SrVMwarer Novice

             

             

            If you remove a Capacity-tier SSD that is the only Capacity-tier device in this Disk-Group the Disk-Group goes away

            If remove a SSD from my Cahce tier for a DiskGroup how that will affect the entire Diskgroup Cache+Capacity tiers?

             

            I am asking since I can't try it at that moment

            • 3. Re: Maintain Cache tier on a vSAN Cluster
              TheBobkin Virtuoso
              VMware EmployeesvExpert

              As I said (and which you quoted) - if you permanently remove the cache-tier SSD this is the same as deleting the Disk-Group. Without the cache-tier device there is essentially no Disk-Group

               

              Bob

              • 4. Re: Maintain Cache tier on a vSAN Cluster
                SrVMwarer Novice

                I though there's a workarounds.

                Many thanks for you help

                • 5. Re: Maintain Cache tier on a vSAN Cluster
                  TheBobkin Virtuoso
                  vExpertVMware Employees

                  One of the main functions of the Cache-tier device is to store metadata describing the layout of the data stored on the Disk-Group and thus without this the data stored on these is functionally useless (other than to just maybe, *MAYBE* Kroll or some other heavy-hitter recovery experts). It's like ripping out the contents page of a book and asking someone to tell you what is on page 57 without looking at page 57 or knowing how to get there.

                  The 'workaround' is removing the Disk-Group with Ensure Accessibility or Full Data Migration.

                   

                  Bob

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