Hard Disk device IDs in Linux

Daniel Fussell dfussell at byu.edu
Fri Mar 8 18:34:20 MST 2013

On 03/07/2013 10:31 PM, Dan Egli wrote:
> *I've got a question. Someone asked me this the other day and I honestly
> couldn't answer them. It's not a situation that one normally comes across,
> but I must admit my curiosity is piqued! :)*
> * *
> *How does Linux handle device IDs for hard disks in excess of 26? I know
> the first hard disk is /dev/sda, the second is /dev/sdb, and so forth. But
> the English alphabet is only 26 letters.
I've had around 60 disks/LUNs connected to one machine.  It started with 
sda - sdz, then sdaa - sdaz, and finished out in the sdba - sdbz range.  
I was using LVM2 to organize them into several different volume groups.

While you can do the disk-by-id that Michael was talking about, I prefer 
to use the good-old-fashioned /dev/sda1 for a small boot partition, and 
everything else is arranged with lvm volumes; that gives me the ability 
to rearrange disk location, and device names I can remember (ie 
/dev/vgmyth/video).  I was a firm believer in gparted back in the day, 
but after learning the wonders of lvm, I rarely ever use parted anymore.

There are people that will try to convince you to skip LVM and use ZFS, 
but everyone I know that was using ZFS took off to the Great White 
North.  ;-)

;-Daniel Fussell

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