Ian said:
Paul,
Do you really need to enable AHCI to get TRIM support?
I got an Intel X25-M 120 GB SSD at a really good price. I installed
64 bit Win 7 Pro, along with various apps on it with my other
drives disconnected, but haven't yet put it into normal service. My
BIOS SATA setting is now at IDE. Right now I'm dual booting
XP Pro and 64 bit Vista Ultimate. The SSD would be introduced
in a tri boot setup using VistaBootPro.
If I change the BIOS to AHCI, will there be any loss of data
integrity on the other two drives?
I can't find a good reference, but along the way, I've seen "msahci"
and "TRIM" mentioned together a lot. I don't think the regular IDE
style driver supports it.
There are options besides TRIM. Some SSDs have built-in garbage
collection. And things like the Intel Toolkit, support manual
TRIM. So in some cases, you can get an equivalent to TRIM, using
a standalone application (left running overnight).
The procedure for flipping your system to AHCI, is here. You have to
"rearm" Windows 7 for the driver change, and that takes a registry
change. Once Windows 7 has identified the right driver, it prevents
the other ones from automatically detecting a hardware change later.
So the "rearm" step is necessary, before shutting down and entering the
BIOS to make the change. I notice in here as well, that some people
are having trouble with the "msahci" driver. The Intel driver package,
generally has AHCI and RAID in the same package, and you could get
AHCI that way. But I don't know whether the Intel AHCI also supports
TRIM - the reason for wanting "msahci" to pick up all the drives,
is it is built in. If you use a separate Intel driver, I don't
know whether you can later "go backwards" or not.
http://www.sevenforums.com/tutorials/61869-ahci-enable-windows-7-vista.html
OK, the bottom of this table, says the Intel RST driver supports
trim, for drives not in a RAID array. If you own two SSDs and they're
running RAID 0, then there is no TRIM used there.
http://www.intel.com/support/chipsets/imsm/sb/CS-022304.htm
"What features are supported on each I/O controller hub (ICH)?
...
TRIM support in Windows 7* (in AHCI mode and in RAID mode for drives
that are not part of a RAID volume"
I presume any AHCI driver is smart enough to query all hard drives, and
see whether they indicate they support AHCI. The same would apply to
using any command queuing protocol (NCQ or TCQ). There is no point in
tagging commands, if the disk isn't paying attention. The driver needs
a fallback, in case a user mixes ancient and modern drivers on the
same computer. If a person wanted, they could use an IDE to SATA adapter
dongle, and then that means the driver would be exposed to some crufty
old drives. Any driver, has to be tolerant of all the various revisions
of ATA/ATAPI specs.
Paul