cvs commit: src/sys/cam/scsi scsi_da.c

[mjacob at freebsd.org]

> I think Windows actually never runs SYNC_CACHE unless you select "detach 
> device".

Maybe for pluggable devices, but otherwise Windows uses SYNC_CACHE and 
FUA quite freely (and correctly).

I'm uncomfortable with the notion that there is uncommitted data present 
in a device after a close that can be lost due to power lossage (or 
unpluggage). From a user application or filesystem point of view, this 
is an axiom violation that no OS should ever allow.

>From a silly semantic point of view to get around this, we should still 
support and require SYNC_CACHE on close except where devices don't 
support it (and any device that hangs on a SYNC_CACHE doesn't support 
it- period). On detach, devices that still need to have data commited 
via an opcode that looks remarkably like SYNC_CACHE can and should have 
that happen- with all the infrastructure changes that go along with 
allowing devices to be detached (w/o complaint) with a live command.

Or have I missed something it what you're suggesting?

-matt