[CentOS] USB install annoyances

John R Pierce pierce at hogranch.com
Mon Jan 9 18:18:56 UTC 2012

On 01/09/12 6:09 AM, John Doe wrote:
> Works fine here...
> On some PCs/servers the key is sdb...

the days of relying on /dev/sd? are long past.

'scsi' devices renumber themselves on every boot.     case in point, 
server I'm configuring now... has a LSI mptsas card with 2 disks 
mirrored for the OS and a megasas2 card with a large raid.   when it 
first came, the megaraid had 2 raids on it, /dev/sda and /dev/sdb and 
the OS on the mpt card was on /dev/sdc .... I deleted these two raids 
and rebooted.   now the OS was on /dev/sda ... I then defined a new 
larger raid60 on the megaraid, this was /dev/sdb   then I rebooted and 
the megaraid was /dev/sda and the boot drive was /dev/sdb

I chose to mount my raid volume with uuid

    |parted /dev/sda ||"mklabel gpt"|
    |parted -a optimal /dev/sda ||"mkpart primary 128k -1s"|
    |mkfs.xfs -f /dev/sda1|
    |uuid=$(xfs_admin -u /dev/sda1 | awk ||'{print $3}'||)   # get the UUID|
    |echo ||"uuid=$uuid /data      xfs     defaults        1 2"| |>
    |mkdir /data|
    |mount /data|

as I had no need for LVM on this configuration, but

I have to say, I like Solaris's traditional disk numbering, 
/dev/dsk/c0t0d0s0 is channel 0, target 0, device 0, lun 0.   the channel 
numbering is generally constant in a given system if you don't juggle IO 
cards around.

john r pierce                            N 37, W 122
santa cruz ca                         mid-left coast

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