independence from ide master/slave

independence from ide master/slave

[Pascal Maillard]

Hi list,

recently, I had changed my IDE disk from primary master to slave. I've got 
SUSE, Debian and Windows XP installed on it. I was ashamed to see that 
Windows loaded immediately, but the Linuxes didn't, because all of the 
filesystems were thought to be on /dev/hda. So I asked myself if there should 
not be device files that point to the _current_ hard disk (which should be 
defined at startup by the kernel) and its partitions. This way, it wouldn't 
matter which IDE channel a disk is connected to. What do you mean about this?

Please cc me!

cö,
Pascal Maillard

Re: independence from ide master/slave

[Andre Tomt]

Pascal Maillard wrote:
> Hi list,
> 
> recently, I had changed my IDE disk from primary master to slave. I've got 
> SUSE, Debian and Windows XP installed on it. I was ashamed to see that 
> Windows loaded immediately, but the Linuxes didn't, because all of the 
> filesystems were thought to be on /dev/hda. So I asked myself if there should 
> not be device files that point to the _current_ hard disk (which should be 
> defined at startup by the kernel) and its partitions. This way, it wouldn't 
> matter which IDE channel a disk is connected to. What do you mean about this?

The kernel already supports identification of partitions through user 
defined labels or UUIDs. If I remember correctly, RedHat uses/used them 
per default.

With other distributions, some tweaking may be needed for the root fs.

man 5 fstab

Re: independence from ide master/slave

[Pascal Maillard]

Hi,

thanks for your answers. I didn't know of UUIDs and user defined labels and 
you're right, it is much more flexible. But, according to man fstab, it is 
currently only supported by ext2 and xfs. What about the others?

One last note about the term "current hd" I used: I did not define it as the 
hd where the root fs is located, but I said that it should be defined by the 
kernel at startup. That is, it could be any disk. The default could have 
been, for example, the root fs.

> perhaps you are thinking of the rather
> specialized case where a system has only one disk, and the root partition
> is on it.
Do you really think, that it is such a specialized case? I know that Linux is 
used much more on servers than on desktop computers, but I suppose we all 
hope that Linux' market share on desktops can grow further.

cö,
Pascal Maillard

Mark Hahn wrote:
> > filesystems were thought to be on /dev/hda. So I asked myself if there
> > should not be device files that point to the _current_ hard disk (which
> > should be defined at startup by the kernel) and its partitions.
>
> "current hd" has no meaning.  perhaps you are thinking of the rather
> specialized case where a system has only one disk, and the root partition
> is on it.  if so, you really mean "/dev/root" (which is a notional device
> that the kernel uses in /proc/mounts for instance - I don't know whether
> it has any assigned major/minor number that would let it appear in /dev.)
>
> note that RedHat has used a relatively simple mechanism called
> mount-by-label which permits the kind of cable/controller independence that
> you're asking for.  it's vastly more logical than your /dev/root approach,
> and extends beyond a single disk.
>
> > This way, it wouldn't
> > matter which IDE channel a disk is connected to. What do you mean about
> > this?
>
> mount by label.