dangerous situation with shutdown process

[Matthias Buelow]

Jon Dama wrote:

>Request Barriers under linux exist to prevent the low level kernel block
>device layer from reordering write operations from the upper file system
>layers.  Request Barriers consist of nothing more than tagging internal
>queues within the Linux kernel itself.  They do nothing to resolve the
>underlying failures of the hardware to provide proper semantics to the
>block device layer.
>but, Request Barriers are ultimately useless.  They can't resolve the
>underlying problems with ide/sata and there are already exposed semantics
>for scsi.

If you flush the cache at barriers, on-disk integrity of the journal
vs. metadata updates is guaranteed.

mkb.