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Old 10-19-2015, 07:26 PM   #1
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Unhappy <Confused> Names for my /dev/sd* devices keep changing automatically at reboot

I'm running RedHat 6.7 on VirtualBox. After adding an additonal hard drive via the VirtualBox Settings and rebooting my virtual server, I find that my sd* devices have been renamed.

For example, before adding the hard drive, my main filesystem is named sda1, sda2, and so on. But once I add a hard drive, my main filesystem will be named sdb1, sdb2 and the added hard drive assumes the sda name. It's very confusing to me.

I added the hard drive under "Controller: SCSI". I'm sorry - I'm a newbie to Linux so forgive me if I am not using the right terms for what I am describing. I appreciate your help.
Old 10-19-2015, 07:38 PM   #2
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Yup. They will. Same thing happens if you plug in USB devices...

The problem is caused by Linux scanning all controllers in parallel. Since it is done in parallel, it now depends on what drive spins up first. With two identical drives, one OR the other can come up first (it also can change depending on which controller is pinged first - add a new controller, expect a new order).

This is why filesystems are mounted either buy using the UUID, or the volume name assigned to the filesystem. Personally, I like volume name, as then I can say "mount volume=backup /mnt" and it always finds the right one.

You can find the UUID or assigned volume names using BLKID.
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Old 10-19-2015, 08:35 PM   #3
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This is an excellent tutorial for using UUIDs in /etc/fstab; it's the one that helped me figure it out.
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