Potential data loss due to disrespect of disk sync (SQLite)

[Technologov]

VirtualBox 4.1.2 being tested with SQLite tests discovered that it disobeys disk sync requests, which can result in data loss. Details here:

​http://www.phoronix.com/scan.php?page=article&item=ubuntu_1110_xenkvm&num=7

-Technologov, 21.12.2011.

[aeichner]

That depends on the VM configuration the author used for the VM. With the default configuration for Linux guests the VM would have a SATA controller with the host I/O cache disabled which passes sync requests to the underlying disk. If the author enabled the host I/O cache however VBox ignores flush requests but it is impossible to say what the author used because the article neither contains the complete configuration nor logs from the run and he didn't contact us as far as I know.

Btw. the behavior can be changed and is documented in the user manual: https://www.virtualbox.org/manual/ch12.html#idp12758688

[Klaus Espenlaub]

This is behaving as documented in the manual. If the phoronix guys want different behavior they can get it, and they should have found it by now...

VirtualBox has a true advantage here, being a type 2 hypervisor. If one assumes that the host OS won't crash then the disk sync can be ignored without data loss.