minor numbers/naming conventions for scsi-drives

minor numbers/naming conventions for scsi-drives

Post by Hartmut Steffi » Sat, 18 Mar 2000 04:00:00

Hi there,
more than once I had trouble with the naming conventions of the
/dev/sd*. They are named sd[n][m], where n stands for the n-th found
disk, and m for a particular partition in sdn. sadly, n has nothing to
do with the scsi-id. so adding or removing a drive (or a drive failure)
cause all subsequent names to change, which obsoletes your fstab, and
you cry: "where is the boot disk?" do you see what i mean? this is not
what I call a system of high availibility.

there are other un*x systems, whose naming conventions are in a way they
never change, because they reflect the physical system. say
/dev/dsk/c[a]t[n]d[l]s[m] denotes to controler a, id n, lun l, slice m
(on a unixware slices system).
i wanted a likewise system. my idea was to mknod my own names on my
devices. but shock! even those names would not be static, as a change on
your scsi bus would make a change to the minor number as well!

quoting 'man sd'
... a minor device number of the form (16  *  drive_number)  +
partition_number, where drive_number is the number of the physical drive
in order of detection ...

this "in order of detection" gives me the headache.
you can find out about your drives after /proc is mounted and make your
nodes at this time. but this is too late in the boot process for your
fstab being right. any idea *not* involving a rewrite of sd.c?



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and minor device number I should use but haven't had any luck.
I thought that solaris would automatically detect my 8mm drive on scsi
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Can someone give me a clue?  Or better yet, tell me where I can find
this information.

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