[CentOS] SCSI install to IDE install - help

[Lamar Owen]

On Monday 24 April 2006 13:47, Erick Perez wrote:
> Hi, a customer has a Centos installation on SCSI disk (aic7xxx), 

> Can I clone the SCSI disk to a IDE Disk with a clone utility such as
> Acronis TrueImage and then rebuild the boot loader?

I've done this.  It is doable, but it is not easy.

First, the partitioning will have to be exactly alike at first (you can resize 
the filesystems, but you want to do that later).

Next, depending upon the IDE controller, you may have to rebuild the initrd 
with mkinitrd.  See the /sbin/new-kernel-pkg script for some ideas on doing 
this and rebuilding the boot loader.  This step, incidentally, is how you can 
migrate from one kind of SCSI controller to another; I've had to do that, 
too, migrating from an Adaptec 39160 to an LSI U320 controller on a CentOS 4 
Intel installation.  

The rescue CD is your friend in those cases, with mkinitrd a close second.  I 
also did the same when migrating an Aurora 2.0 boot drive on a Sun Enterprise 
6500 from a D1000 shelf hung off a diff SCSI qLogic controller to the 
single-ended drive tray and the ESP controller.  I also took another boot 
drive from a Ultra 30 (which uses a PCI NCR 53c875 SCSI controller) to an 
E5500 with the qLogic diff SCSI and a D1000 (for those who don't know, the 
D1000 has high voltage differential SCSI inputs, but uses ultra wide LVD/SE 
drives internally); booted the Aurora 2.0 CD in rescue mode, chrooted to the 
drive, ran mkinitrd with the proper options, and rebooted.  Came right up.  
Note that the rescue CD does need to be the same major kernel version as the 
system. 

Now, the part that is most important.  See /etc/fstab and make sure all 
occurrences of /dev/sdaX are replaced with the matching /dev/hdaX (where X is 
the partition number).  However, some ATA controllers (particularly SATA 
controllers) act like SCSI and use /dev/sdaX instead; be careful.  If the 
filesystems are mounted with labels, you may not have to do this except for 
the swap partition.

I did this once going the other way, from an IDE disk to a SCSI disk. It 
worked fine, but was a little tedious.
-- 
Lamar Owen
Director of Information Technology
Pisgah Astronomical Research Institute
1 PARI Drive
Rosman, NC  28772
(828)862-5554
www.pari.edu