When an X58 + ICH10 based machine (Dell Precision T3500) was upgraded to ESXi 7, the storage adapter and associated datastore was lost.  The ICH10 in this case was not playing well with the native vmw_ahci driver.  In AHCI mode, the adapter shows up as a 6 port controller in vSphere (Host -> Manage ->  Hardware of PCI devices. However none of the attached drives appear under Storage.  Also attempting to toggle PCI passthrough for the device results in an error:

An error occurred during host configuration.  Operation failed, diagnostics report: GetDeviceID failed.

Refreshing vSphere would then show as the host needing a reboot for it to take effect. However upon rebooting passthrough is still  disabled / not active.

To resolve, the SATA adapter was switched from AHCI to IDE / ATA mode in the BIOS.  This allowed the controller and all attached drives to appear in vSphere by using the native vmkata driver.  This change will also passthrough to be enabled, but it requires a reboot.

However another issue was that a VMFS datastore on the drive attached to this controller was no longer accessible.  To resolve, the datastore had to be force mounted. These steps were used to manually mount the datastore:

1. In the console / shell:

   esxcli storage vmfs snapshot list

2. Check fore an output similar to this:Volume Name: datastore1
   VMFS UUID: <snip>
   Can mount: true
   Reason for un-mountability:
   Can resignature: true
   Reason for non-resignaturability:
   Unresolved Extent Count: 1

3. Determine the Volume Name, e.g., (datastore1), this acts as the label

4. Mount it using the label. In this example, datastore1:

   esxcli storage vmfs snapshot mount -l datastore1

5. Refresh the Storage section of vSphere

Note: performance in ATA / IDE mode may be reduced compared to AHCI