how do I detect the HDD's on the system?

[Rudi Ahlers]

Hi

I want to setup different software RAID levels, according to the number 
& type of drives in the actual system. My problem is, I often have 
systems with mixed IDE & SATA drives.

I found the following website, 
http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/sysadmin-guide/s1-kickstart2-preinstallconfig.html 
which has some neat tricks on detecting the IDE drives, but the same 
techniques doesn't apply for SATA drives ( I don't even know how SAS / 
SCSI drives operate on Linux, since I haven't worked with them yet)

The basis of the script is as follows:


for file in /proc/ide/h*
do
  mymedia=`cat $file/media`
  if [ $mymedia == "disk" ] ; then
      hds="$hds `basename $file`"
  fi
done

set $hds
numhd=`echo $#`

drive1=`echo $hds | cut -d' ' -f1`
drive2=`echo $hds | cut -d' ' -f2`

It doesn't indicate which drive is first in the list, which could be a 
problem is the cdrom is on HDA for example (mine is, due to the 2U case 
layout and how the IDE cable runs)

With SATA (which uses scsi emulation), the process is different. There's 
no /media folder in /proc/scsi/ - only a scsi file, which lists all the 
devices:

 cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3250410AS      Rev: 3.AA
  Type:   Direct-Access                    ANSI SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST3250410AS      Rev: 3.AA
  Type:   Direct-Access                    ANSI SCSI revision: 05


dmesg | grep sd
SCSI device sda: 488395055 512-byte hdwr sectors (250058 MB)
SCSI device sda: drive cache: write back
SCSI device sda: 488395055 512-byte hdwr sectors (250058 MB)
SCSI device sda: drive cache: write back
 sda: sda1 sda2
Attached scsi disk sda at scsi0, channel 0, id 0, lun 0
SCSI device sdb: 488397168 512-byte hdwr sectors (250059 MB)
SCSI device sdb: drive cache: write back
SCSI device sdb: 488397168 512-byte hdwr sectors (250059 MB)
SCSI device sdb: drive cache: write back
 sdb: sdb1 sdb2



So, how does the system know that scsi0 = sata1 ?

I'd like to find this out, cause it will make the RAID setup much easier 
for mixed systems

-- 

Kind Regards
Rudi Ahlers
CEO, SoftDux

Web:   http://www.SoftDux.com
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