Bug#514967: grub-mkdevicelist does not cope with /boot on a disk > #16

[Chris Samuel]

----- "Robert Millan" <rmh at aybabtu.com> wrote:

> So what is the actual limit ?

For 2.4 the limit appears to be 2,304 disks, according
to this IBM article:

http://publib.boulder.ibm.com/infocenter/dsichelp/ds8000ic/index.jsp?topic=/com.ibm.storage.ssic.help.doc/f2c_linuxscsilimit_2hsag9.html

In 2.6 I'm not sure if there is a fixed limit, this LWN
article from 2004 about the (then) forthcoming 2.6.5 release
indicated that it could be up to one million disks!

http://lwn.net/Articles/75928/

> And how are disks named after we reach /dev/sdz ?

On our system it goes to sdaa, sdab, sdac, sdag, sdae,
etc, so I'd say an alphanumeric base 26 I guess.. ;-)

Aha - found it in the kernel git repository - there is a
function in drivers/scsi/sd.c called  sd_format_disk_name()
which sorts this out - the comment for it says:

/**
 *      sd_format_disk_name - format disk name
 *      @prefix: name prefix - ie. "sd" for SCSI disks
 *      @index: index of the disk to format name for
 *      @buf: output buffer
 *      @buflen: length of the output buffer
 *
 *      SCSI disk names starts at sda.  The 26th device is sdz and the
 *      27th is sdaa.  The last one for two lettered suffix is sdzz
 *      which is followed by sdaaa.
 *
 *      This is basically 26 base counting with one extra 'nil' entry
 *      at the beggining from the second digit on and can be
 *      determined using similar method as 26 base conversion with the
 *      index shifted -1 after each digit is computed.
 *
 *      CONTEXT:
 *      Don't care.
 *
 *      RETURNS:
 *      0 on success, -errno on failure.
 */

cheers,
Chris
-- 
Christopher Samuel - (03) 9925 4751 - Systems Manager
 The Victorian Partnership for Advanced Computing
 P.O. Box 201, Carlton South, VIC 3053, Australia
VPAC is a not-for-profit Registered Research Agency