Server vNext 25987, 26010 (and Server 2022) deduplication corruption in nested-V setups

Iron Contributor

The deduplication corruption in the case of nested virtualization in Server 2022 and Server 25987 is still there.

The package to reproduce for Server 25987:

Server 2022 variant:

Host OS can be Server 2019, Windows 11 21H2 or Server 2022.

CPU must be reasonable fast (i.e. from somewhere 'round 2018), support nested-v together with the Host OS (AMD and Intel CPU are fine). Host should have at least 24 GB RAM. The the "ready to reproduce package" must be unpacked to D: or higher drive letter which should be at least SATA SSD storage. Else the problem may not show up as predictable as it does here.

These packages were exported from a Server 2019 host, HP DL 380 dual Xeon 6228R with 1 TB ECC RAM, so it is easier to reproduce since Exports from Windows 11 don't import so well on other hosts. Originally the bug showed up on a Ryzen 5950x with 64 GB ECC RAM. Reproduced with less than 50% chance on an i7-4960x 32 GB RAM with HDD storage, more than 50% on SSD storage.

Server 2019 variant: Does exist, but there is no data corruption.

How to use: Once unpacked to Non-System-Drive SSD storage import the the VM and follow the Textfile on the desktop.

In short:

Activate Hyper-V in that VM, default settings.

Configure deduplication with default settings any profile in that VM for D:, start a dedup run. Check dedup rate. Should be above 50%, usually it is around 55%.

Import those two VMs on drive D: of that VM:

Start them both in parallel, and execute the Offline-Windows-Updates stored on the desktop. You won't make it past the first one.

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