[parted-devel] [dm-devel] What is the deal with the partition separator?

[Hannes Reinecke]

On 02/16/2011 08:37 PM, Phillip Susi wrote:
> On 2/16/2011 2:38 AM, Hannes Reinecke wrote:
>> The linux scheme since the dawn of time is to
>> a) Add the partition number to the device node name
>> b) If last letter of the device node name is a number, insert a 'p'
>> between device node name and partition number
> 
> Since the dawn of time?  Before device mapper it wasn't possible to have
> a disk device name ending in a digit.
> 
Unless you happen to have a raid HBA, which has names like

cciss/c0d0

or

rd/c0d0

and, of course, you can have partitions on md devices, too, which
will also give you names like
md0p1

>> with the advent of persistent device names (via udev) the partition
>> separator (for persistent links only!) is '-part'.
>>
>> So you have
>>
>> /dev/sda
>> /dev/sda1
>> /dev/disk/by-id/scsi-0WhatAStupidName
>> /dev/disk/by-id/scsi-0WhatAStupidName-part1
>>
>> persistent device names are longish anyway, so we can as well use
>> something readable for partitions.
> 
> That's fine for the symlinks in by-id, but what about the names in
> /dev/mapper and /dev/VG?
> 
/dev/mapper contains the names of the device-mapper devices
themselves; for those I don't have any preference.
kpartx as called from udev is using the '-part' suffix here, too.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
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