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Sorry if I don't have the correct terminology, I am still somewhat a linux novice.

I have a computer with four hard drives (sda, sdb, sdc & sdd) in it. I am going to add a fifth (sde) which will replace two others (sdb & sdc).

Adding the drive and moving data to it is the easy part for me. What happens when I physically remove the other two disks? Will the labels move down? Will I need to manually edit fstab and fix the problem?

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up vote 5 down vote accepted

Letters are assigned on the basis of which drive gets enumerated first. The first drive gets /dev/sda, the second /dev/sdb, etc. If you want to avoid having to modify /etc/fstab then you should consider using the filesystem labels or UUIDs instead of the device node.

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Can you expand on filesystem labels and UUIDs? What is the "best practice"? –  Tom H. May 12 '11 at 14:46
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@Tom H.: In most places where you can specify a device as /dev/sdX, you can also specify it by giving its UUID or (sometimes) the filesystem or volume label. See e.g. ubuntuforums.org/showthread.php?t=283131 for a good explanation. The advantage of using UUID or label is that they don't change when you rearrange the hardware; fs labels can even be kept when you change a drive (because they are assigned manually, and not a property of the hardware). –  sleske May 12 '11 at 14:54
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Labels can be and UUIDs are assigned to each filesystem that is formatted. They can be viewed with the blkid command, and used wherever a device node would be for mount (such as in /etc/fstab) if preceded by LABEL= or UUID=. –  Ignacio Vazquez-Abrams May 12 '11 at 14:57
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