2TB Limit using the Image Conversion tool

Article Number: 
269

Problem

The ShadowProtect image conversion tool limits the size of conversions to a partition or a volume size of less than 2TB. ShadowProtect indicates this limitation appears in one of two ways:

      1. The ShadowProtect image conversion tool in versions 4.1.5 and earlier issues an error when attempting to convert a backup image file containing an oversized volume into a VHD or VMDK disk.

        14-Dec-2012 10:01:44 sbrest 411 Cannot create new virtual disk file E:\backups\big conversion.vmdk (-87 The parameter is incorrect.
         

      2. The ShadowProtect image conversion tool in versions 4.2x and later greys out either or both the options for VHD and VMDK disks after selecting an image file containing an oversized volume:

Either way, a question remains: “Precisely how close to 2TB can the partition or volume be?”           

Cause:

Both Microsoft and VMware hypervisors limit virtual disks to under approximately 2TB. While Microsoft has introduced a new format, VHDx, in Windows Server 2012/Windows 8, which does support volumes greater than 2TB, ShadowProtect does not yet support this new format. Note too that this 2TB limit is for the partition/volume size, not for the amount of data within the volume. Even if the volume has only 1 byte of data, if the volume is 2.5TB in size, the tool fails to convert the file.

However, it is not clear from the onscreen error or the ShadowProtect dialog how close to the 2TB limit that the ShadowProtect conversion tool will support.

Resolution:

The ShadowProtect image file to virtual disk conversion tool supports volumes of these maximum sizes:

Destination Virtual Disk Type

Maximum Source Volume Size in Mebibytes (1 MiB equals 1,048,576 bytes)

Maximum Source Volume Size in Bytes

Maximum Source Volume Size in ~TB

Hyper-V fixed .vhd

2097140 MiB (2048_GiB – 12 MiB)

2,199,010,672,640 bytes

approximately 2.2TB

Hyper-V dynamic or differencing.vhd

2088948 MiB (2040_GiB – 12 MiB)

2,190,420,738,048 bytes

approximately 2.19TB

VMware VMDK

2097140 MiB (2048_GiB - 512 bytes - 12_MiB)

2,199,010,672,128 bytes

Approximately 2.19TB

Note:

Microsoft allows Dynamic and Differencing .vhds to be up to 2088960_MiB (2040_GiB or 2,190,433,320,960 bytes)  in size. However, ShadowProtect reserves 12 MiB (12,582,912 bytes) (shown in the chart deducted from the full volume size) for possible use by Dynamic Disk metadata in both vhd and vmdk converted volumes. 

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