I've a general question concerning SATA AHCI vs IDE mode

[wilcal]

This being set in newer BIOs in the

PCH SATA control mode

The choices are

IDE
RAID
AHCI

I'm considering an SSD on my primary system
and looking through all the stuff on SSD's
they recommend the AHCI mode. But I find I've
installed Mageia 1 in the IDE mode. Probably
a mistake at the time. As a test I've installed
Mageia 1 64-bit on a scratch drive in IDE mode
and then changed the BIOs back and forth between
IDE and AHCI. Both settings seem to boot normally.
Would there be any risk in installing Mageia 1/2
in the IDE mode then changing the mode to AHCI?
I see there's problems with older WinBlows
OS's. Not destructive problems just boot
problems. Changing back to IDE makes things
work again. Seems not to effect Mageia.

Note: Newer Gigabyte MoBo

Thanks

[doktor5000]

For linux it shouldn't matter, but you won't be able to use features of SATA controllers like Native Command Queueing or other improvements like eSATA hot-plugging if you don't use AHCI mode.

For older windows it's still possible to switch this, but it's not easy and it's not trivial, and if you do it wrong you get a bluescreen and can't undo this.

[GlennsPref]

Hi, I have found that booting to win(x) in ide mode and installing the mobo drivers,

then at reboot, switch the bios to ahci, then save and reboot to boot win(x).

This should finish off the driver installer for windows to run with sata-ahci, instead of ide.

Make sure you turn off the backup app (in bios) because it will wait during boot, for the backup-device to be found, taking upto 2 minutes (or more).

Linux will still work, because the kernel has most of what you need installed at boot.

HTH, Glenn

[JoesCat]

Installing Mageia 1 in IDE mode wasn't a mistake, it was simply what you are used to.

Right now, there still exists computers that are IDE, AHCI, and/or a combination of both. For Linux to be useful for the most users, Linux will generally be setup with both IDE and AHCI enabled for now, and probably the near future until IDE is obsolete for "a while" (eg, several years?).

If you want to set your machine to run in AHCI mode and you have a simple setup that uses a fixed number of drives, you probably note it "just works".
If it doesn't, it's probably because a drive or a partition got guessed wrong since it's possible that what may have been seen as /dev/sdX in IDE mode gets seen as /dev/sdY in AHCI mode. Try the terminal console and see if the results of df are the same in IDE and AHCI modes. If yes, then you are okay.

Would there be any risk in installing Mageia 1/2 in the IDE mode then changing the mode to AHCI?

I would recommend installing in AHCI mode, then try IDE mode. Look at the /etc/fstab file and you'll notice that most partitions are defined as UID but have the older /dev/sdX definitions commented. If it doesn't boot-up in IDE mode, then uncomment the /dev/sdX values and comment the UID values, but realize that you might not be able to use some features like hotplug.

With older Windows like XP, you'll need to search and find the appropriate AHCI drivers and put them on a floppy disk (you will likely find them in a zip file or subdirectory on the CDrom that comes with the motherboard), then when you install windows (XP), you need to press something like F2 or F8 to tell Windows you need to install extra custom drivers from floppy disk during the installation process. You should do this install in AHCI mode, not IDE mode.

If you are going to play with SSD, reading will be fast, but writes may be a bit slower depending on the drive you have.
You'll want to investigate setting the queue depth to get some throughput on the writes. Try something like queue depth of 8, 16 or 32 since the default is likely 1 right now. Also check the cables since some SATA cables are rated for higher speeds.