Opened 8 years ago
Last modified 7 years ago
#17200 new enhancement
Disable COW for disk images on btrfs
| Reported by: | darkdragon | Owned by: | |
|---|---|---|---|
| Component: | virtual disk | Version: | VirtualBox 5.1.30 |
| Keywords: | btrfs, cow, copy-on-write | Cc: | |
| Guest type: | other | Host type: | other |
Description
Since copy-on-write (COW) feature of modern file systems (e.g. BtrFS) decreases the performance of disk images significantly, it should be turned off by default.
Therefore, I suggest adding a checkbox in the "New VM" and "VM Properties" dialogues to disable COW and set this by default.
This way, the user still has full control, nothing happens "in the background" without the user noticing and it is a useful default for most of the users!
See some discussion on this topic in #11862
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Please be aware that in case of BTRFS disabling COW also disables checksums, which are an integral part of the file system.
Also see the BTRFS FAQ