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The problem is known by many, but what is the correct way to solve it:
when I installed a pci-ide controller my drives changed, my root formerly sda5 is now sdb5 and the attached ide-disk is now sda*
-should I just live with this and change the fstab etc
-or should I change /dev/sdb to /dev/sda and vice versa, if so how?
I read something on these fora that I 'd have to use udev but I think it's fairly complicated so if someone could give me a kickstart
- in the past I also had that pci-ide installed but everything worked as expected
-grub still uses the 'old' configuration
-(just a thing I'd like to know 'df' still shows '/' mounted to /dev/sda5 with the correct usage, while sda5 doesn't even exist how is this possible?)
I haven't run into much trouble with the SCSI/Sata/USB assigning disk sdx yet but that may be because I do not use a pci-ide controller.
I think there is a logical to it that how the sdx is prioritised.
It is possible that there is a table Linux checks in handing out the disk order and the PCI-IDE controller may be ahead of the onboard Sata port or it could be just an unanticipated condition hence a mistake.
If your controller is a PCI card that controls IDE devicee, like a Pata disk, then the disk should have been named either hda, hdb, hdc or hdd.
However if all the 4 IDE devices have been used up then there is no possible IDE device for the PCI-IDE controller. Linux permits 64 raw devices in a Pata and the combination of 4 IDE disks time 64 raw devices give exactly 256 devices.
The only way the attached disk can be read would be to treat it as a SCSI/Sata/Usb device. Different Bios can react differently to it so may be it is only your mobo gives the sda to the PCI-IDE controlled device whereas other Mobo may do the opposite. Linux accepts 16 raw devices in each of the 16 SCSI/Sata/Usb disks to make up the 256 devices.
I take it in your your case you just can't swap the sda with the sdb disk because one is a Pata while the other is a Sata.
Dunno saikee, I don't have an answer for you.
I ran into the partition (count) limitation just the once - on a (real) SCSI raid 5 array.
You're at the more extreme end of the range, but others are going to bump into this. Haven't looked at it to be honest - I'll have a look at lkml and see if it's been raised amongst the kernel devs.
Maybe LVM is the answer - despite the fact that neither you or I have embraceed it yet. A few PV with logical volumes to suit.
Something else to look at ....
Normally I would have said fix fstab and live with it - but your comments on grub and df in your initial post are "interesting".
Maybe I'll build a up system with P-ATA and S-ATA over the weekend and see if I get similar.
Or maybe I'll mow the yard ... we'll see.
Before the Sata disk was born IDE/Pata and SCSI disks are distinguished by the different major and minor number systems for the devices.
SCSI can be daisy-chained with up to 16 devices requiring a terminator resistor at the end device to indicate that it is the last of the chain. SCSI disks always require a driver loaded before it can be recognised and the number of devices will be detected/scanned in each booting. Sata is a variation of SCSI famaily and USB disks also fit in with the SCSI disk family which is software-driven.
IDE/Pata disks are controlled by mobo hardware which makes the disk available to an operating system without the need of a driver, at least that is how it works on all the MS systems.
The Linux 256 raw devives in each hard disk type is achieved by 4 IDE devices, of hda, hdb, hdc and hdd, each with 64 names of hda, hda1, hda2....to hda63. All the PC mobo I have seen have only two IDE channels each has a cable handling a master and a slave.
Sata disks are recent invention and individual ports are provided. However the 256 raw devices are achieved by the maximum 16 disks each with 16 devives names from sda, sda1, sda2...to sda15.
The above is the hardware limit according to the major/minor number system designed to address such hard disks.
According to the established Linux convention it is not possible to increase the device names of the a SCSI/Sata/USB disk. I have removed a 63-partition Pata disk say it is a hda and plugged it into the same PC as an external hard drive. It became sda. However Linux knows there are 63 partitions inside and that is not permitted and so none of the partition can be read. If I want to use it then the whole disk has to be formatted to start afresh. That disk when hooked back as an internak disk works perfectly again as a hda.
I don't doubt that Linux can alter the protocol to read a Pata as a Sata. The question is really is it worth it? Think of all the servers and existing PC that may run into trouble if the sdx change is mandatory. If the change isn't mandatory then more unwarranted problems are introduced into Linux.