Re: Maximum number of logical partitions

[Andreas Janssen <andreas.janssen@bigfoot.com>]

Hello

Pete Clarke (<pete@dynotechnic.co.uk>) wrote:

> Does anyone know the maximum number of partitions that can be created
> on a SCSI disc?
> I have Googled and come up with the following:
> 
> Primary - 4.
> 
>     SCSI - 15 logical;
>     IDE   - 63 logical.
> 
> Seems a bit odd?

Seems to be (mostly) correct. Take a look at the minor numbers of
thedevice files:

brw-rw----    1 root     disk       8,   1 2004-05-21 03:20 /dev/sda1
[...]
brw-rw----    1 root     disk       8,  15 2004-05-21 03:20 /dev/sda15
brw-rw----    1 root     disk       8,  16 2004-05-21 03:20 /dev/sdb
brw-rw----    1 root     disk       8,  17 2004-05-21 03:20 /dev/sdb1
[...]
brw-rw----    1 root     disk       8,  31 2004-05-21 03:20 /dev/sdb15

sda15 is major 8, minor 15, sdb is major 8, minor 16. sda can have
partitions from sda1 (8/1) ro sda15 (8/15). The next device file (8/16)
is sdb. Now the IDE files:

brw-rw----    1 root     disk       3,   1 2004-05-21 03:20 /dev/hda1
[...]
brw-rw----    1 root     disk       3,  64 2004-05-21 03:20 /dev/hdb
brw-rw----    1 root     disk       3,  65 2004-05-21 03:20 /dev/hdb1

hda1 is major 3, minor 1. hdb is major 3, minor 64. That means that for
hda you can have device entries from 3/1 to 3/63 = 63 partitions. The
first logical partition is 3/5 (hda5).

best regards
        Andreas Janssen

-- 
Andreas Janssen <andreas.janssen@bigfoot.com>
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http://www.andreas-janssen.de/debian-tipps.html