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Linuxhelp _ Technical Support _ USB external drive and SCSI conflict

Posted by: LoDeSp Jun 22 2008, 02:12 PM

I'm having a problem with my USB external hard drive and my internal SCSI drive. Both work fine once I've got the system booted.

However, when I try to boot with the USB drive plugged in, Linux identifies my USB drive as sda and my SCSI drive as sdb. Then it mounts sda as root, which fails because the root is on the SCSI drive, which is now sdb. I really want the naming to be the reverse (SCSI always == sda), so that I can boot with the USB drive either plugged in or not. My workaround for the moment is to unplug the USB drive whenever I reboot and plug it in after the SCSI drive has been identified as sda and mounted. That works, but it's clunky. So how can I get the USB drive to be identifed as sdb? Can I modify the order that the kernel does hardware initialization so that SCSI goes first? It seems that USB is done before SCSI now...

Thanks for any help.

Posted by: michaelk Jun 22 2008, 03:51 PM

What linux distribution/version are you running? There are several ways. You can use uuid, partition labels in fstab or udev rules to always mount a particular partition to a specifc mount point.

Posted by: LoDeSp Jun 22 2008, 04:08 PM

QUOTE (michaelk @ Jun 22 2008, 03:51 PM) *
What linux distribution/version are you running? There are several ways. You can use uuid, partition labels in fstab or udev rules to always mount a particular partition to a specifc mount point.


I'm using Debian unstable. I've tried using udev, and I've gotten the USB hard drive to mount as usbhd, but that still doesn't fix the problem. I created a new file called 10-local.rules to mount the USB drive as usbhd. Is there another rule before this that is identifying it as sda before 10-local.rules applies?

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