## VirtualBox压缩VDI格式硬盘/调整磁盘大小

http://www.virtualbox.org/manual/ch08.html#vboxmanage-modifyvdi

• With the --compact option, can be used to compact disk images, i.e. remove blocks that only contains zeroes. This will shrink a dynamically allocated image again; it will reduce the physical size of the image without affecting the logical size of the virtual disk. Compaction works both for base images and for diff images created as part of a snapshot.For this operation to be effective, it is required that free space in the guest system first be zeroed out using a suitable software tool. For Windows guests, you can use the sdelete tool provided by Microsoft. Executesdelete -z in the guest to zero the free disk space before compressing the virtual disk image. For Linux, use the zerofree utility which supports ext2/ext3 filesystems.Please note that compacting is currently only available for VDI images. A similar effect can be achieved by zeroing out free blocks and then cloning the disk to any other dynamically allocated format. You can use this workaround until compacting is also supported for disk formats other than VDI.

Using SDelete

SDelete is a command line utility that takes a number of options. In any given use, it allows you to delete one or more files and/or directories, or to cleanse the free space on a logical disk. SDelete accepts wild card characters as part of the directory or file specifier.

1,  在guest os 中清理系统， windows的话可以再硬盘碎片整理一下

2,  在 guest os 中 使用 sdelete -z  ； linux 使用 zerofree

3,  VBoxManage modifyhd <uuid>|<filename>  --compact