USB HD SCSI ID Problem

USB HD SCSI ID Problem

Post by Strangel.. » Sat, 19 Feb 2005 18:33:00



Apologies if this is not the right place.

I have a slackware 10.1 linux System with 6 SATA HD's in it - they
appear as /dev/sda-f -
I also have 6 USB external HD [used as a backup system] - never at the
samne time - but they change 1 /day

the 1st two days are OK as the USB HD show up as
/dev/sdg then /dev/sdh

I hope you can see where I'm going with this...

when I add the 3rd USB HD - I run out of SCSI ID letters in /dev/ -
i.e. there is no
/dev/sdi-m

now the qestion -

how do I add extra sd devies to /dev ?
or is that not sensible ?
or how do I find my extra USB HD in the system and get them mounted?

All help gladly received.

 
 
 

USB HD SCSI ID Problem

Post by Dances With Crow » Sun, 20 Feb 2005 00:07:28



Black Sun and said:

Quote:> Apologies if this is not the right place.

Right place, wrong Subject: .  USB devices don't *have* SCSI IDs; the
SCSI device nodes are used because USB Mass Storage commands are pretty
similar to SCSI commands.

Quote:> I have a slackware 10.1 linux System with 6 SATA HDs in it - they
> appear as /dev/sda-f .  I also have 6 USB external HDs.  the 1st two
> days are OK as the USB HD show up as /dev/sdg then /dev/sdh
> when I add the 3rd USB HD - I run out of SCSI ID letters in /dev/ -
> i.e. there is no /dev/sdi-m

> how do I add extra sd devies to /dev ?  or is that not sensible ?

Of course it's sensible to want to add devices to a static /dev.  The
default Slackware installation only includes /dev/sd[a-h] because not
that many people have more than 8 SCSI disks, and the people who do have
that many SCSI disks are assumed to know how to use mknod.  "man mknod",
then check /usr/src/linux/Documentation/devices.txt for the major and
minor numbers you need.  /dev/sd[i-m] all have major 8, minors vary, so
you could do this:

MINOR=128      # minor for /dev/sdi
for DEV in i j k l m ; do
    mknod /dev/sd$DEV b 8 $MINOR
    let MINOR=$MINOR+16
    done

...this only creates device nodes for the whole disks.  If you need
nodes for the partitions on the disks, you'll have to modify the script.

Quote:> or how do I find my extra USB HD in the system and get them mounted?

Slackware is not really for the novice user.  If you are a novice user,
you will have a much better time with another distro.  HTH,

--
Matt G|There is no Darkness in Eternity/But only Light too dim for us to see
Brainbench MVP for Linux Admin /    mail: TRAP + SPAN don't belong
http://www.brainbench.com     /                Hire me!
-----------------------------/ http://crow202.dyndns.org/~mhgraham/resume

 
 
 

USB HD SCSI ID Problem

Post by John-Paul Stewar » Sun, 20 Feb 2005 00:51:41



> Apologies if this is not the right place.

> I have a slackware 10.1 linux System with 6 SATA HD's in it - they
> appear as /dev/sda-f -
> I also have 6 USB external HD [used as a backup system] - never at the
> samne time - but they change 1 /day

> the 1st two days are OK as the USB HD show up as
> /dev/sdg then /dev/sdh

> I hope you can see where I'm going with this...

> when I add the 3rd USB HD - I run out of SCSI ID letters in /dev/ -
> i.e. there is no
> /dev/sdi-m

I see you've already recieved a good answer about creating more entries
in /dev.  But I'll also point out that if you unload the usb-storage
module (after removing the USB drive), the kernel will "forget" about
it.  Then you reload the module, plug in the next drive, and it will be
/dev/sdg.  So by loading and unloading the module you'll always have
your backup at /dev/sdg, if you want.

BTW, it's not entirely clear to me what will happpen after you've used
/dev/sdm.  When you re-attach the first hard drive it may not get
re-assigned its former designation of /dev/sdg.  It might get /dev/sdn
instead.  IOW, there's a chance that the system will just keep counting
until you unload/reload the usb-storage module, reboot, or run out of
SCSI disk nodes (of which there are 256 possibilities).

 
 
 

USB HD SCSI ID Problem

Post by Anton Er » Sun, 20 Feb 2005 18:43:26



>I also have 6 USB external HD [used as a backup system] - never at the
>samne time - but they change 1 /day

>the 1st two days are OK as the USB HD show up as
>/dev/sdg then /dev/sdh

Yes, I have seen this on some kernels.  However, the 2.6.5 kernel I
use at home and the 2.6.9 kernel on my laptop seem to always assign
the first free SCSI id to USB-storage devices.

So, I suggest that you try a new kernel.

- anton
--
M. Anton Ertl                    Some things have to be seen to be believed

http://www.complang.tuwien.ac.at/anton/home.html

 
 
 

USB HD SCSI ID Problem

Post by Strangel.. » Tue, 22 Feb 2005 20:18:48




> > Apologies if this is not the right place.

> > I have a slackware 10.1 linux System with 6 SATA HD's in it - they
> > appear as /dev/sda-f -
> > I also have 6 USB external HD [used as a backup system] - never at the
> > samne time - but they change 1 /day

> > the 1st two days are OK as the USB HD show up as
> > /dev/sdg then /dev/sdh

> > I hope you can see where I'm going with this...

> > when I add the 3rd USB HD - I run out of SCSI ID letters in /dev/ -
> > i.e. there is no
> > /dev/sdi-m

> I see you've already recieved a good answer about creating more entries
> in /dev.  But I'll also point out that if you unload the usb-storage
> module (after removing the USB drive), the kernel will "forget" about
> it.  Then you reload the module, plug in the next drive, and it will be
> /dev/sdg.  So by loading and unloading the module you'll always have
> your backup at /dev/sdg, if you want.

aha - I'll also have a look at that - that may be useful for something
else.[also]

Quote:> BTW, it's not entirely clear to me what will happpen after you've used
> /dev/sdm.  When you re-attach the first hard drive it may not get
> re-assigned its former designation of /dev/sdg.  It might get /dev/sdn
> instead.  IOW, there's a chance that the system will just keep counting
> until you unload/reload the usb-storage module, reboot, or run out of
> SCSI disk nodes (of which there are 256 possibilities).

when they get re-atatched they get their old designation - so the 1st
one goes back to being sdg etc.
 
 
 

USB HD SCSI ID Problem

Post by Strangel.. » Tue, 22 Feb 2005 20:16:18




> Black Sun and said:
> > Apologies if this is not the right place.

> Right place, wrong Subject: .  USB devices don't *have* SCSI IDs; the
> SCSI device nodes are used because USB Mass Storage commands are pretty
> similar to SCSI commands.

I slob corrected - but you knew what I ment [and so do I now]

Quote:> > I have a slackware 10.1 linux System with 6 SATA HDs in it - they
> > appear as /dev/sda-f .  I also have 6 USB external HDs.  the 1st two
> > days are OK as the USB HD show up as /dev/sdg then /dev/sdh
> > when I add the 3rd USB HD - I run out of SCSI ID letters in /dev/ -
> > i.e. there is no /dev/sdi-m

> > how do I add extra sd devies to /dev ?  or is that not sensible ?

> Of course it's sensible to want to add devices to a static /dev.  The
> default Slackware installation only includes /dev/sd[a-h] because not
> that many people have more than 8 SCSI disks, and the people who do have
> that many SCSI disks are assumed to know how to use mknod.  "man mknod",
> then check /usr/src/linux/Documentation/devices.txt for the major and
> minor numbers you need.  /dev/sd[i-m] all have major 8, minors vary, so
> you could do this:

> MINOR=128      # minor for /dev/sdi
> for DEV in i j k l m ; do
>     mknod /dev/sd$DEV b 8 $MINOR
>     let MINOR=$MINOR+16
>     done

I did :-
for dev in i j k l m n o p; do ./MAKEDEV sd$dev ; done

and let MAKEDEV take the strain

Quote:

> ...this only creates device nodes for the whole disks.  If you need
> nodes for the partitions on the disks, you'll have to modify the script.

> > or how do I find my extra USB HD in the system and get them mounted?

> Slackware is not really for the novice user.  If you are a novice user,
> you will have a much better time with another distro.  HTH,

not really a novice - just never had to play with this part before ;-P

Thanks - it is all working now.

 
 
 

1. ide-scsi, 1394-sbp2 and usb-storage scsi host ids

JimC> In all 2.4 versions I've tested, (the most recent of which are
JimC> 2.4.20-pre4-ac1 and 2.4.20-pre8), ide-scsi, sbp2 and usb-storage
JimC> all use scsi host id 0.

I don't see that I posted an update to this.  In 2.4, this was fixed
at some cset between v2.4.20-pre8 and v2.4.20-rc1.

-JimC

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