How to virtualize a protected system with 4K Advanced Format disk volumes - x360Recover

Written By Tami Sutcliffe (Super Administrator)

Updated at August 16th, 2021


x360Recover 10.7.0 now supports a simple automated mechanism for booting a protected system with native 4K Advanced Format disk volumes

Previous releases required a complicated manual driver installation process for these drives.

What is a 4K Advanced Format disk?

Until relatively recently, all computer disk drives were manufactured with 512 bytes of physical block size for data storage.  

In 2010, manufacturers shipped the first prototype 4K Advanced Format drives to hardware vendors for experimental use. 4K Advanced Format drives are able to store 4096 bytes (4K) in each block.  Since 2010, these 4K Advanced Format drives have slowly entered the market in production. 

The physical space saved by combining (eight) 512-byte blocks into a single 4096-byte block is about 7-11% of total platter space. This space savings is due to combining the redundant block headers into a single set.

Why does this matter?

Block size determines the smallest amount of data storage that a file can consume. 

  • A 1-byte file consumes an entire block on the disk.
    • On a traditional drive, this 1-byte file would consume 512 bytes.
    • On a 4K Advanced Format disk, this 1-byte file requires 4096-bytes. 

Disk structures, partitions, and volume sizes are also calculated as:

(Number of blocks)  x  (Block size)

So, it is important to understand this size difference when manipulating disk data. 

Most importantly, partitions must begin and end on a block boundary, and the underlying storage controller driver must be 4K-Advanced-Format-block-aware to process these drives correctly.

How has 4K Advanced Format affected virtualization and recovery? 

The legacy compatibility storage controller emulation in KVM does not understand or support 4K Advanced Format block devices.

This means that it was not possible to construct a 4K Advanced Format virtual disk to be compatible with the default IDE controller emulation used for virtualizing a protected system in x360Recover. 

4K Advanced Format drives are only supported using VirtIO storage controller modes within KVM.  

Windows does not include native driver support for VirtIO. This has historically meant that VirtIO drivers must be installed into our virtual machine images via a complicated manual process  - before such machines could be booted as a virtual machine.

P2V to the rescue

x360Recover 10.7.0 and newer now implements a complex P2V (Physical to Virtual) conversion process to groom the protected system and stage it for recovery prior to boot.

Among other things, P2V can now inject native VirtIO drivers into the offline system automatically -  prior to boot - eliminating the complicated manual driver injection process.

4K Advanced Format physical disk drives are automatically detected when present in a protected system.  VirtIO will automatically be enabled by default when 4K Advanced Format drives are present.  (The virtual block device cannot be constructed without enabling VirtIO).


VirtIO will also automatically be enabled for Boot VM Checks (AutoVerify) if 4K Advanced Format drives exist - for the same reason.




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