Here's what I learned:
#1: Always use the /R:1 switch with ROBOCOPY. Failure to do so today cost me 1.25 hours.
#2: This server has neither iDrac Express nor iDrac Enterprise, it also lacks the Lifecycle Controller and Unified BIOS of newer Dell servers. So, downloaded the bootable Systems Build and Update Utility (SBUU)...and got stuck...so downloaded the 10GB Dell Server Update Utility and ran it under Windows 2008 R2 to apply firmware updates for the RAID controller, HDs, NICs, etc.
#3: On Hyper-V Server 2012 R2, to see what devices are missing a driver, use the free Portlock Device Manager.
#4: PNPUTIL -i -a was useless. In Hyper-V Server 2012 R2, if drivers aren't available through Windows Update, forget about it.
#5: You can install the Dell Server Manager 7.4 on Hyper-V Server 2012 R2.
Installation: msiexec /i SysMgmtx64.msi
Web access: https://hostname:1311/OMSALogin
#6: The Dell Server Administrator (GUI and CLI) did not show current values for the RAID rebuilding process. Restarting the "DSM SA Data Manager" service in Windows refreshed it. omreport storage vdisk is the command to show RAID rebuild progress.
Lastly, wanted to convert my original dynamic VHDs to fixed VHDXs for better performance thru reduced fragmentation (link, link).
First, tried New-VHD -Path c:\file.vhdx -Fixed -SourceDisk 3 -SizeBytes 50GB, but that doesn't work. Here's what does:
Mount-VHD -Path original.vhd -Readonly (the host OS acts like it's an attached drive now)
Get-Disk (to identify what number is assigned to the VHD mentioned above)
New-VHD -Path new.vhdx -Fixed -SourceDisk 3 (duplicates the original into a fixed VHDX)
Optionally reduce the size of the VHDX file:
LIST VOLUME (to see which volume number to select)
SELECT VOLUME 6 (for example)
SHRINK QUERYMAX (to see how much empty space there is (reference))
SHRINK DESIRED=50000 (sets the partition size to 50GB in this example)
Resize-VHD new.vhdx -ToMinimumSize
Replace the old VHD with the shiny new VHDX:
Get-VMHardDiskDrive -VMName SBS (optional)
Remove-VMHardDiskDrive -VMName SBS -ControllerLocation 0 -ControllerNumber 0 -ControllerType IDE
Add-VMHardDiskDrive -VMName SBS -ControllerLocation 0 -ControllerNumber 0 -ControllerType IDE -Path new.vhdx
So, you ask, did I achieve the goal of improved disk I/O? Yes, but don't die from laughter when you see the numbers - these are SATA disks on a Perc H200 RAID controller (write cache is disabled).
For what it's worth, moving from RAID 1 to RAID 10 nearly doubled R/W performance of the Hyper-V host. The graphs below are from inside a Hyper-V guest.
To benchmark disk performance, I used DiskSpd with a sample set of parameters from the download page: diskspd.exe -b8K -d30 -h -L -o2 -t4 -r -w30 -c50M c:\io.dat
...and I just discovered Crystal DiskMark! Post-upgrade numbers: