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Old 12-01-2007, 12:49 PM   #1
bhoch
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Question RHEL4U5 install changes /dev/sda to /dev/sdb


I am installing RHEL4U5 and when I go through the install panels I am creating the following:

/dev/sda1 as /
/dev/sda2 as /test
/dev/sda3 as swap
/dev/sda5 as /data (/dev/sda4 is created automatically..)

In this system I have 1 hard drive.

I then install and system installs just fine.

If I go to a prompt and type in "df" I get /dev/sdb1, /dev/sdb2, /dev/sdb5 showing up. It's like RedHat changed my drive designations.

If I install REHL4U4 to this same box, (same exact method as I install RHEL4U5) I get /dev/sda1, etc.. so from a hardware standpoint it appears to be Okay?

Any thoughts would be appreciated!
 
Old 12-01-2007, 01:31 PM   #2
ehawk
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Perhaps you should also post here:

http://www.centos.org/modules/newbb/...m.php?forum=27
 
Old 12-01-2007, 03:03 PM   #3
David1357
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Quote:
Originally Posted by bhoch View Post
I am installing RHEL4U5 and when I go through the install panels I am creating the following:

/dev/sda1 as /
/dev/sda2 as /test
/dev/sda3 as swap
/dev/sda5 as /data (/dev/sda4 is created automatically..)

In this system I have 1 hard drive.

I then install and system installs just fine.

If I go to a prompt and type in "df" I get /dev/sdb1, /dev/sdb2, /dev/sdb5 showing up. It's like RedHat changed my drive designations.

If I install REHL4U4 to this same box, (same exact method as I install RHEL4U5) I get /dev/sda1, etc.. so from a hardware standpoint it appears to be Okay?

Any thoughts would be appreciated!
The output of

# ls -al /dev/sd*

will help us to help you. Although you only have one hard drive installed, the kernel may be seeing some other device (maybe a CD-ROM drive) and declaring it to be sda. Also, the output of "dmesg | less" will let you search for sda and see what the kernel thinks it it.

The sad fact is that the kernel developers change things around so much between releases that sometimes a device shows up as hdX (where X is a lowercase letter) in one kernel (e.g. a CD-ROM) and sdX in another.
 
Old 12-03-2007, 09:06 AM   #4
bhoch
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Hi.
Of interest:

The "ls -as /dev/sd*" command gives following output:

brw-rw---- 1 root disk8, 0 Dec 1 05:21 /dev/sda
brw-rw---- 1 root disk8, 16 Dec 1 05:21 /dev/sdb
brw-rw---- 1 root disk8, 17 Dec 1 05:21 /dev/sdb1
brw-rw---- 1 root disk8, 18 Dec 1 05:21 /dev/sdb2
brw-rw---- 1 root disk8, 19 Dec 1 05:21 /dev/sdb3
brw-rw---- 1 root disk8, 20 Dec 1 05:21 /dev/sdb4
brw-rw---- 1 root disk8, 21 Dec 1 05:21 /dev/sdb5

The "dmesg" command output for sda and sdb shows:

Attached scsi removable disk sda at scsi0, channel 0, id 0, lun 0


- then it shows the RW/DVD and has info about the keyboard, mouse.
- After going through info about them it gets to the harddrive and shows the info below. At this point, it then selects sdb for the harddrive ordering...

scsi2 : ioc0: LSI53C1030 line which shows the vendor and type for the hard drive and then the following is added:

SCSI device sdb: 143372288 512-byte hdwr sectors (73407 MB)
SCSI device sdb: drive cache: write through
SCSI device sdb: 143372288 512-byte hdwr sectors (73407 MB)
SCSI device sdb: drive cache: write through
sdb: sdb1 sdb2 sdb3 sdb4 <sdb5>
Attached scsi disk sdb at scsi2, channel 0, id 0, lun 0
SELinux: initialized (dev sdb1, type ext3), uses xattr
EXT3 FS on sdb1, interanl journal
EXT3 FS on sdb5, interanl journal
SELinux: initialized (dev sdb5, type ext3), uses xattr
EXT3 FS on sdb3, internal journal
SELinux: initialized (dev sdb3, type ext3), uses xattr
Adding 10241428k swap on /dev/sdb2. Priority: -1 extents:1


So, for some reason it appears that the install does see sda Okay, but apparently the kernel is using it for the removable disk (CDROM or floppy). Is there something I need to change to have the drive be correctly read as sda or is this just they way is is now? It's odd, as this does not happen on RHEL4U4. But I have not ran any commands to see how it compares between the two of these...

Thanks,
Bill
 
Old 12-03-2007, 12:25 PM   #5
bhoch
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OK - this is figured out - Understood.. no.. but figured out.

If I have the CD drive selected when I boot the system, it gets /dev/sda and the drive(s) then /dev/sdb, etc..
If the CD is NOT selected then the Drives get /dev/sda and when I then select the CDROM it then gets the /dev/sdb.

So, apparently, nothing really needs to change. Our backup/restore items will need to change how we setup the fstab and grub.conf files..

Thanks!

Bill
 
Old 12-03-2007, 06:38 PM   #6
David1357
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Quote:
Originally Posted by bhoch View Post
OK - this is figured out - Understood.. no.. but figured out.

If I have the CD drive selected when I boot the system, it gets /dev/sda and the drive(s) then /dev/sdb, etc..
If the CD is NOT selected then the Drives get /dev/sda and when I then select the CDROM it then gets the /dev/sdb.
What do you mean by "selected"?
 
Old 12-04-2007, 05:16 PM   #7
bhoch
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Quote:
Originally Posted by David1357 View Post
What do you mean by "selected"?
Hi David - on the front of the blade, you can select the video and the cd,floppy via two buttons. By selected I mean that I have the cdrom/floppy drive selected (accessable) by that system or not. I hope that makes it's clearer then mud!

Bill
 
Old 12-04-2007, 06:33 PM   #8
David1357
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Quote:
Originally Posted by bhoch View Post
Hi David - on the front of the blade, you can select the video and the cd,floppy via two buttons. By selected I mean that I have the cdrom/floppy drive selected (accessable) by that system or not. I hope that makes it's clearer then mud!
Yes, that clears up my confusion. Basically, you are adding and removing the CD-ROM from the system by pressing a button. That kind of thing confuses most Linux installations. One way around this is to use UUIDs to mount partitions, but it is a PITA if the drive goes bad.
 
Old 12-05-2007, 07:33 AM   #9
bhoch
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Quote:
Originally Posted by David1357 View Post
Yes, that clears up my confusion. Basically, you are adding and removing the CD-ROM from the system by pressing a button. That kind of thing confuses most Linux installations. One way around this is to use UUIDs to mount partitions, but it is a PITA if the drive goes bad.
David - Thanks for the help and followup on this one. What appears to work fine is if we do the following:

We are creating 4 partitions - /dev/sda1, /dev/sda2, /dev/sda3, /dev/sda4

/dev/sda1 and 3 are each bootable, with /dev/sda2 as our swap partition and /dev/sda4 as a data partition that both boot drives use.

Using labels in the fstab and /boot/grub/grub.conf seems to all everything to work fine and it does not seem to matter what the /dev/sd* selection is when the system is booting after that. So, we are changing all of our backup/restore tools to use this method instead of the /dev/sd* naming convention and we should be good.

Thanks for the followup and help!

Bill
 
  


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