hard disk issue

lliw00 · n00b Joined: 26 Feb 2008 Posts: 37 Location: The Universe

ey whenever i install gentoo, i always have to use /dev/hda when every other os i try recognizes the drive as /dev/sda is this a problem buried in the minimal install kernel? is it a problem with my southbridge?
any help would be good, thanks
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Jaglover · Posted: Mon Mar 03, 2008 3:23 am Post subject:

didymos · Posted: Mon Mar 03, 2008 3:28 am Post subject:

It be the kernel. Upgrade the kernel after installation, and you can revert to /dev/sda. There's a kernel option to disable the old ide stuff, but I can't remember it at the moment.
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Thomas S. Howard

didymos · Posted: Mon Mar 03, 2008 3:31 am Post subject:

lliw00 · n00b Joined: 26 Feb 2008 Posts: 37 Location: The Universe

so after i chroot into the new environment, i should start using sda where i used hda?
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Jaglover · Posted: Mon Mar 03, 2008 3:52 am Post subject:

You write sda in the fstab, you build your kernel with libata (disable IDE/EIDE support).

lliw00 · n00b Joined: 26 Feb 2008 Posts: 37 Location: The Universe

should i disable eide support even though i still have eide drives?
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didymos · Posted: Tue Mar 04, 2008 7:17 am Post subject:

You've got the wrong idea. There are two (somewhat) parallel sets of drivers. One, when you use menuconfig is referred to as "ATA/ATAPI/MFM/RLL support". This is the old IDE subsytem that's been around for ages, and it's conventions dictate that drives are referred to as hd<letter><number>. Initially, SATA stuff was handled within this subsystem, and it can still be used with early SATA controllers. That has changed. The new subsystem is referred to as libata, and under menuconfig appears as "Serial ATA (prod) and Parallel ATA (experimental) drivers". Parallel ATA is the same thing as IDE/EIDE. Despite the "experimental" tag, most of the PATA (which is to say, IDE) drivers are actually very well tested. The most visible difference between the old subsystem and libata is that now all drives, PATA or SATA, are given names following the sd<letter><number> convention. For SATA, libata is pretty much the only way to go, unless, as I said, you've got some early hardware in your system. For PATA/IDE you've got a choice- old drivers or new.

Now, you can have both types of drivers at the same time. For example, say you've got an Intel chipset with the, umm, ICH7 controller, which allows for both PATA and SATA drives. OK, so you build in "Intel ESB, ICH, PIIX3, PIIX4 PATA/SATA support", the libata driver. You also build in "Intel PIIXn chipsets support", the old IDE subsytem driver. And, in your system you've got one SATA drive and one IDE drive, each plugged into their respective connectors. So, what driver does the IDE drive use?

By default, the kernel will use the old IDE one and your disk is called /dev/hda. Your SATA drive uses the libata driver, and it is called /dev/sda. But, you don't actually need "Intel PIIXn chipsets support" anymore. "Intel ESB, ICH, PIIX3, PIIX4 PATA/SATA support" covers both drive types. So, you disable the IDE driver. Now there is no more /dev/hda. Instead, you've got /dev/sda and /dev/sdb. Either one could be the SATA drive, just as either one could be the IDE drive. That depends on how the BIOS numbers the drives. That is to say, hda could be either sda or sdb. So, you want to know what the BIOS considers to be the 1st drive before you alter fstab.

It's a little odd at first glance, but the reason for it is to provide a transitional period between the two subsystems. Eventually, the old IDE drivers will disappear and there will be only libata. Until then, the driver duplication will persist. For the most part, the two can coexist happily, but there are cases on newer systems where mixing the drivers can cause problems, especially on newer machines where the vendor has set defaults in the BIOS that assume you'll only be using SATA devices and SATA-aware drivers. Sometimes, these settings aren't exposed and can't be changed by the user. For that, and other reasons, it's just better overall to use the new libata stuff and completely disable the old IDE drivers.
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Thomas S. Howard