Mailinglist Archive: opensuse (4570 mails)

[Gerhard den Hollander <gdenhollander@xxxxxxxxxxxxxxx>]

* Ken Schneider <suse-list@xxxxxxxxxxxxx> (Thu, Nov 03, 2005 at 08:06:01AM -0500)

>>>> and the new disk is number 3, hdd. I can not install grub there, nor can I 
>>> I thought the third disk would be hdc, doesn't matter how it is attached
>>> to the controller.

>> Yes, but Unix is based on C, and there we start counting with 0
>> So 1st harddisk is hard disk number zero is hd0/hda
>> The disk number 3 / hd3 is then hdd
>> (which means it's the slave on the secondary IDE channel)

> So... do you have three disks or four? Disk numbering by the system
> (based on "c") starts at 0, but quantity (not based on "c") starts
> counting at 1. When I was learning math in school and the teacher held
> up four fingers and asked how many fingers we saw the answer was four
> not three.
> Hence your forth disk would be hdd "d" being the forth letter of the
> alphabet, and it would not be hd0/hda as there is no hd0, there is hda0
> meaning the first partition on the first drive.
> :-)

Ok,
first, I was not clear enough.

Disk numbering is based on where the disk is w.r.t. your controller
(assuming we use IDE)
Primary Master -> hda (hd0)
Primary Slave  -> hdb (hd1)
Secondary Master> hdc (hd2)
Secondary Slave-> hdd (hd3)

So if your only disk is a secondary slave (unlikely, but possible) the
first disk (quantity 1) would be hd3/hdd

You are right about quantity though ;)

However, to confuse matters even more, partitions start at 1

So the first partition on the first drive is hda1

(and to confuse it even more, if you use extended partitions, the first
partition is hda5 )


And then be glad the system is not a sun,
where the first disk could be anything like:
/dev/rdsk/c7t4d0s2 

(8th controller, scsi Id of disk 4 , 1st device, slice 2 )

where of course the 8th controller was not necesarily controller 8
and IDE disks were emaulated to have the same CxtXdXsX numbering scheme

and slice 2 indicates the whole disk.




> -- 
> Ken Schneider
> UNIX  since 1989, linux since 1994, SuSE  since 1998

	Gerhard, <faliquid@xxxxxxxxx>   == The Acoustic Motorbiker == 	
-- 					and family


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