Opened 12 days ago
#22394 new enhancement
update the user guide for compressing VDI images on Linux guests
| Reported by: | squid10 | Owned by: | |
|---|---|---|---|
| Component: | documentation | Version: | VirtualBox-7.1.8 |
| Keywords: | user manual, documentation, compact, VDI | Cc: | |
| Guest type: | Linux | Host type: | all |
Description
For Linux guests, the VirtualBox user guide currently states that for compressing a VDI image with VBoxManage modifymedium --compact, the zerofree utility only supports ext2 and ext3, but it also supports ext4, and there are other ways to zero free space on other filesystems which are not mentioned.
The current VBoxManage modifymedium section:
Linux guests. Use the
zerofreeutility, which supportsext2andext3file systems.
The zerofree utility currently supports ext4 as well, see the Debian man page:
zerofree — zero free blocks from ext2, ext3 and ext4 file-systems
For btrfs and other filesystems, blkdiscard --zeroout --verbose could be used, see the Debian man page:
blkdiscard - discard sectors on a device
Some online forums suggest also using sfill -llz from the secure-delete package (available in Debian and Arch AUR, but not Fedora). Debian man page:
sfill - secure free disk and inode space wiper (secure_deletion toolkit)
