id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host
16099,"Possible Disk Corruption with total data loss, caused by VDI resize.",mpack,,"I'm writing this to draw attention to a discussion about a VDI disk which seems to have been corrupted (boot sector erased to all zeros) after it was resized by VBoxManage. We've had two or three similar reports in recent weeks, but I think this is the first I've dug into.

Discussion here:
https://forums.virtualbox.org/viewtopic.php?f=8&t=80233

The drive had 54933 allocated blocks at the time it was resized, from about 55GB, to exactly 65000MB.

On examining the corrupted header I found that the blockmap had a 4K alignment, but the image started at 1MB - not consistent with a 64GB drive using 4K alignment.  I'm wondering if either (a) you have bug whereby a section of resizing code assumes 1MB alignment, or perhaps (b) you attempt to realign the VDI to 1MB boundaries but fail part way through due to a host error. The latter feature would require all blocks to be moved, this might explain why the early sectors are zeroed.

This corruption leaves the drive effectively wiped (no partition map), and all data lost. The shuffling of blocks would render recovery of any data well nigh impossible.",defect,closed,virtual disk,VirtualBox 5.1.6,fixed,vboxmanage VDI resize corruption,,Windows,Mac OS X