[VMC] VMDK files not being selected properly when reconfiguring/creating a replication from seed data.

Products

• VMware Cloud on AWS
• VMware Cloud on Dell EMC

Issue/Introduction

To help provide a solution to a customer to ensure successful replication reconfigurations/creation and correct vmdk files names being used when using seed data. 

Symptoms:
A customer may be reconfiguring a current replication or creating a new replication using seed data and are getting the error, "The capacity of the seed disk does not match the capacity of the replication source disk. Create a new seed copy or verify that you selected the correct seed to use for this replication."

Cause

In most cases the customer has increased/decreased the size of the Source VM Hard Disk which is causing a mismatch in the Hard Disk sizes between VMC and OnPrem. Customer confirmed they are using seed data to reconfigure the replication. A possible issue are some vmdk files are reporting false seed data file names and some Hard Disks are not having the seed data automatically filled in through the UI. This can be caused by a customer removing a replication and recreating it rather than reconfiguring the current replication. 

Resolution

In order to confirm the correct vmdk file name is being used for the target seed data, follow the below process using the Source Hard Disk RDID to find the correct vmdk file name on the target side using vRealize Log Insight (use vRealize Log Insight if available - this is an additional feature that comes at a cost to a customer). 

1. Gather the RDID information for the Source Hard Disk vmdks - steps to gather the RDID are below:
   1. Obtain the VM UUID from the source vCenter: VM name -> Actions -> Edit Settings -> VM Options -> General Options -> VM Working Location -> Copy and paste the UUID.
   2. ssh into the Source ESXi host where the VM currently lives.
   3. Run the command to get into the correct location: cd vmfs/volumes/datastore_for_the_vm/UUID_captured_earlier.
   4. Run the command "grep -E 'RDID|vmdk' VM_Name.vmx |grep -v psf" to display and see what the Source VM vmdk file name the RDID is associated to.
2. Using the RDID information for the Source Hard Disks, login to vRealize Log Insight to obtain the vmdk file name that is associated with the RDID:
   1. When logged into vRealize Log Insight, there will need to be three filters: (Line 1) SDDC ID, (Line 2) RDID-################################, (Line 3) consolidatedisks, (Line 4 - Optional) VM Name.
   2. Similar output should be seen - <99>vrs-3 hbrsrv[887]: 2023-04-20T12:22:06.360Z info hbrsrv[11958] [Originator@6876 sub=Host opID=hsl-a829cf35] Starting ConsolidateDisks task=haTask--vim.VirtualDiskManager.consolidateDisks for [child=[] /vmfs/volumes/vsan:#################################################/hbrdisk.RDID-###################################.vmdk into parent=[] /vmfs/volumes/vsan:#########################################/VM_NAME_##.vmdk] with host=host-8000
   3. In the above output, using the RDID information (Child section) we can see the associated vmdk file name on the target side (Parent section) which shows the VM_NAME_##.vmdk. Using this information, you can ensure the correct vmdk file name is being used when selecting seed data.
3. Once we have the target vmdk file names, we can reconfigure the replication for the VM(s) and ensure the seed data vmdk file names being auto selected for the source hard disks are correct to avoid any disk mismatches. If they are not correct, we can edit the seed data vmdk file, and using the information gathered can select the correct target vmdk file name. 

If nothing is showing up in Log Insight, please create an SR with VMC GS to request assistance. 

Additional Information

Impact/Risks:
Customer will not be able to reconfigure their replication(s) until the Hard Disk mismatch is successfully remediated.