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Image Compatibility between older Macs and USB-C MacBooks, MacBook Pros (FIXED)

Winclone 5 customers only

This issue is fixed in Winclone 6.

Winclone 5 customers intending to migrate Boot Camp from an older Mac to the USB-C Mac models like 2016 MacBook Pro or 2015 Mac Book should be aware of an incompatibility between the drive block size (see full article below) that prevents successful Winclone migration in Winclone 5.  


Image Compatibility between older Macs and 2016 Macbook Pro and USB-C MacBook

The USB-C MacBook and MacBook Pro models have drives that use native advanced format 4096-bytes-per-sector drives. Larger block size means that large files can be written faster, since more data can be written at one time. However, this mean that file systems and drivers must be block size-aware. Previous MacBook and MacBook Pro models use 512 byte emulation even though the physical sectors are 4K. The Master File Table (MFT) on the internal drive also uses a larger segment size than the older drives.*

For several years, hard drive manufacturers have been transitioning drives from 512 byte sector size to 4096 byte sector size. Hard drives have had physical sector sizes of 4096 bytes for many years, but the controllers in these drives present logical sector size as 512 bytes in emulation (512e) to support older computer hardware and operating systems. The drive controllers in the USB-C MacBook present native 4096 bytes (advanced format) logical sectors to the operating system rather than 512 bytes.  

What does this mean for cloning Boot Camp?  Cloning between older Macs and new USB-C Macs is not currently possible.  Winclone images of Boot Camp from older hardware cannot be restored to bootable systems on the USB-C MacBook and MacBook Pro hardware and vice versa.

To see what logical sector size is used on the Mac, open Terminal and enter:

 diskutil info / | grep "Block Size".

Non-USB-C Macs will show the device block size (or logical sector size) as 512 bytes while the USB-C MacBook shows 4096 bytes.  Compare the device block size and if they are different, then the image cannot be cloned due to data size incompatibility.

Non-USB-C_Mac$ diskutil info / | grep "Block Size"
Device Block Size: 512 Bytes
Allocation Block Size: 4096 Bytes

USB-C_Mac$ diskutil info / | grep "Block Size"
Device Block Size: 4096 Bytes
Allocation Block Size: 4096 Bytes

The device block size is the raw block size used by the hard drive controller hardware and cannot be changed. The Allocation Block Size is used by the file system and is set when formatting and partitioning drives.

When the logical sector size for the destination disk differs from logical sector size stored in the Winclone image (from a source disk), the restored image will not have an valid partition table, will not mount and will not boot.

Additional information can be found by starting Boot Camp and view sector info with fsutil. Running Windows 8.1 on a MacBook Pro and USB-C MacBook, we find the bytes per sector (device block size) differences as well as master file table (MFT) size shown by bytes per file record segment differences.

MacBookPro_BootCamp> fsutil fsinfo ntfsinfo c:

Bytes Per Sector : 512

Bytes Per Physical Sector : 4096

Bytes Per Cluster : 4096

Bytes Per FileRecord Segment : 1024

Clusters Per FileRecord Segment : 0


USB-C_MacBook_BootCamp> fsutil fsinfo ntfsinfo c:

Bytes Per Sector : 4096

Bytes Per Physical Sector : 4096

Bytes Per Cluster : 4096

Bytes Per FileRecord Segment : 4096

Clusters Per FileRecord Segment : 1


* The master file table (MFT) use file record segments in 1024-byte units, whereas the USB-C MacBook's drive uses file record segments in 4096-byte segments. 


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