[gentoo-user] mount: "special device /dev/hdc does not exist". What does this mean?

[gentoo-user] mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Gentoo?

I've a newly installed system, now working with my own special
optimiesed keyboard layout.  :-)

However, I can't access my DVD drives.  I know at least one of them
works, because I installed Gentoo from it.

When I do

   mount -tiso9660 /dev/hdc /cdrom

, it comes back with "special device /dev/hdc does not exist".  And yes,
there was a CD in the drive, and /cdrom exists.

What does "special device" mean here?  Does it mean the physcial
hardware, the controller chip, the directory entry /dev/hdc, the driver
in the kernel, or what?  What is "special" about my DVD writer?

Well, to answer some of my questions, I was missing a /dev/hdc, so I
made one with

# mknod /dev/hdc b 22 0

.  This didn't help one iota.  I had a look at dmesg, but there was no
mention of hdc in it.  (It did mention hdg, hdh, where my main hard
drives are (don't ask!)).

My kernel is an up to date linux-2.6.25-gentoo-r6.  I _think_ it's got
all the needed options set in the configuration.  Can anybody suggest
how to get my system to recognise my DVD drives?

Thanks in advance!

-- 
Alan Mackenzie (Nuremberg, Germany).
-- 
gentoo-user@lists.gentoo.org mailing list

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Alan Mackenzie wrote:
> Hi, Gentoo?
> 
> I've a newly installed system, now working with my own special
> optimiesed keyboard layout.  :-)
> 
> However, I can't access my DVD drives.  I know at least one of them
> works, because I installed Gentoo from it.
> 
> When I do
> 
>    mount -tiso9660 /dev/hdc /cdrom
> 
> , it comes back with "special device /dev/hdc does not exist".  And yes,
> there was a CD in the drive, and /cdrom exists.
> 
> What does "special device" mean here?  Does it mean the physcial
> hardware, the controller chip, the directory entry /dev/hdc, the driver
> in the kernel, or what?  What is "special" about my DVD writer?

/dev/hdc (and other files in /dev) are not called "files", they're 
called "special devices").


> Well, to answer some of my questions, I was missing a /dev/hdc, so I
> made one with
> 
> # mknod /dev/hdc b 22 0
> 
> .  This didn't help one iota.  I had a look at dmesg, but there was no
> mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> drives are (don't ask!)).

Use /dev/sdc instead of /dev/hdc.  The default in new kernels is to only 
use /dev/sd*.

-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Nikos,

On Sat, Jul 19, 2008 at 10:06:15PM +0300, Nikos Chantziaras wrote:
> Alan Mackenzie wrote:

> >However, I can't access my DVD drives.  I know at least one of them
> >works, because I installed Gentoo from it.

> >When I do

> >   mount -tiso9660 /dev/hdc /cdrom

> >, it comes back with "special device /dev/hdc does not exist".  And yes,
> >there was a CD in the drive, and /cdrom exists.

> >What does "special device" mean here?  Does it mean the physcial
> >hardware, the controller chip, the directory entry /dev/hdc, the driver
> >in the kernel, or what?  What is "special" about my DVD writer?

> /dev/hdc (and other files in /dev) are not called "files", they're 
> called "special devices").

Ah!  I really wish they weren't.  Didn't they used to be called "device
files"?

> >Well, to answer some of my questions, I was missing a /dev/hdc, so I
> >made one with

> ># mknod /dev/hdc b 22 0

> >.  This didn't help one iota.  I had a look at dmesg, but there was no
> >mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> >drives are (don't ask!)).

> Use /dev/sdc instead of /dev/hdc.

I booted up in to the kernel, did # ls /dev/sd*, and the only things
displayed were /dev/sda and /dev/sda1.  That is the place where my USB
stick gets mounted.

> The default in new kernels is to only use /dev/sd*.

I'm totally confused.  Doesn't "sd*" mean "SCSI disk drive"?  When I was
installing Gentoo from the CD, I had to mount my main hard drive as
/dev/sdb5.  When I built my own kernel, it needed /dev/hdh5.

This seems crazy.  Is it documented anywhere in Gentoo?

-- 
Alan Mackenzie (Nuremberg, Germany).

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Alan Mackenzie wrote:
>> The default in new kernels is to only use /dev/sd*.
> 
> I'm totally confused.  Doesn't "sd*" mean "SCSI disk drive"?  When I was
> installing Gentoo from the CD, I had to mount my main hard drive as
> /dev/sdb5.  When I built my own kernel, it needed /dev/hdh5.
> 
> This seems crazy.  Is it documented anywhere in Gentoo?

Not sure.  But if you have /dev/hd* instead of /dev/sd*, it means you 
configured your kernel with the legacy IDE drivers instead of the new 
(P)ATA drivers.  The new drivers use /dev/sd* (for IDE/PATA/SATA and 
SCSI alike; there's no difference anymore.)

The CD/DVD-ROM can show up as /dev/sd* even with the old legacy drivers 
if you have enable "SCSI Emulation" for it.

In any event, try to build a new kernel using the new drivers.  The old 
legacy driver you're using will probably get declared "deprecated" at 
some point (if it didn't happen already).

To enable the new drivers, first disable the legacy drivers.  ("Device 
Drivers" section):

     < > ATA/ATAPI/MFM/RLL support  --->

Now enable the new drivers:

    <*> Serial ATA (prod) and Parallel ATA (experimental) drivers  --->

Enter that section and pick your chipset.  Don't enable the:

    < >   Generic ATA support

unless you can't find a native driver for your chipset (I doubt you have 
some extremely rare/exotic mainboard ;)

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Mick]

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On Saturday 19 July 2008, Nikos Chantziaras wrote:
> Alan Mackenzie wrote:
> >> The default in new kernels is to only use /dev/sd*.
> >
> > I'm totally confused.  Doesn't "sd*" mean "SCSI disk drive"?  When I was
> > installing Gentoo from the CD, I had to mount my main hard drive as
> > /dev/sdb5.  When I built my own kernel, it needed /dev/hdh5.
> >
> > This seems crazy.  Is it documented anywhere in Gentoo?
>
> Not sure.  But if you have /dev/hd* instead of /dev/sd*, it means you
> configured your kernel with the legacy IDE drivers instead of the new
> (P)ATA drivers.  The new drivers use /dev/sd* (for IDE/PATA/SATA and
> SCSI alike; there's no difference anymore.)
>
> The CD/DVD-ROM can show up as /dev/sd* even with the old legacy drivers
> if you have enable "SCSI Emulation" for it.
>
> In any event, try to build a new kernel using the new drivers.  The old
> legacy driver you're using will probably get declared "deprecated" at
> some point (if it didn't happen already).
>
> To enable the new drivers, first disable the legacy drivers.  ("Device
> Drivers" section):
>
>      < > ATA/ATAPI/MFM/RLL support  --->
>
> Now enable the new drivers:
>
>     <*> Serial ATA (prod) and Parallel ATA (experimental) drivers  --->
>
> Enter that section and pick your chipset.  Don't enable the:
>
>     < >   Generic ATA support
>
> unless you can't find a native driver for your chipset (I doubt you have
> some extremely rare/exotic mainboard ;)

What would be the recommended way of upgrading from the /dev/hd to /dev/sd 
then?  I have held back doing this because I didn't have the time to mess 
about with it.  If I were to configure a new kernel without legacy ATA 
drivers, how would I know what my devices will be seen as in advance, so that 
I can change my /etc/fstab before I reboot?
-- 
Regards,
Mick

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[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Mick wrote:
> [...]
> What would be the recommended way of upgrading from the /dev/hd to /dev/sd 
> then?  I have held back doing this because I didn't have the time to mess 
> about with it.  If I were to configure a new kernel without legacy ATA 
> drivers, how would I know what my devices will be seen as in advance, so that 
> I can change my /etc/fstab before I reboot?

The way I do it, is to label my partitions.  If your partitions aren't 
labeled yet, you can do so with 'tune2fs'.  If your /dev/hda1 is your 
root (/), /dev/hda2 your /home and /dev/hda3 your swap, you can label 
them with:

   tune2fs -L GentooRoot /dev/hda1
   tune2fs -L GentooHome /dev/hda2
   mkswap -L GentooSwap /dev/hda3

Then edit /etc/fstab and change the mount points from:

   /dev/hda1 ...
   /dev/hda2 ...
   /dev/hda3 ...

to:

   /dev/disk/by-label/GentooRoot
   /dev/disk/by-label/GentooHome
   /dev/disk/by-label/GentooSwap

As reference, here the relevant entries in my own /etc/fstab:

   /dev/disk/by-label/GentooRoot /          ext3    noatime 0 1
   /dev/disk/by-label/GentooSwap none       swap    sw      0 0
   /dev/disk/by-label/Suckage    /windows/C ntfs-3g noatime 0 0

As you can see this even works for NTFS; you use the label you gave the 
drive in Windows.

After you've done these changes, it doesn't matter the least anymore 
what the actual device name is.  You can even move the harddisk to 
another computer (actually I'm doing exactly that) that totally results 
in a re-ordering of /dev/sd* entries and it will still mount correctly.

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Dale]

Nikos Chantziaras wrote:
> Mick wrote:
>> [...]
>> What would be the recommended way of upgrading from the /dev/hd to 
>> /dev/sd then?  I have held back doing this because I didn't have the 
>> time to mess about with it.  If I were to configure a new kernel 
>> without legacy ATA drivers, how would I know what my devices will be 
>> seen as in advance, so that I can change my /etc/fstab before I reboot?
>
> The way I do it, is to label my partitions.  If your partitions aren't 
> labeled yet, you can do so with 'tune2fs'.  If your /dev/hda1 is your 
> root (/), /dev/hda2 your /home and /dev/hda3 your swap, you can label 
> them with:
>
>   tune2fs -L GentooRoot /dev/hda1
>   tune2fs -L GentooHome /dev/hda2
>   mkswap -L GentooSwap /dev/hda3
>
> Then edit /etc/fstab and change the mount points from:
>
>   /dev/hda1 ...
>   /dev/hda2 ...
>   /dev/hda3 ...
>
> to:
>
>   /dev/disk/by-label/GentooRoot
>   /dev/disk/by-label/GentooHome
>   /dev/disk/by-label/GentooSwap
>
> As reference, here the relevant entries in my own /etc/fstab:
>
>   /dev/disk/by-label/GentooRoot /          ext3    noatime 0 1
>   /dev/disk/by-label/GentooSwap none       swap    sw      0 0
>   /dev/disk/by-label/Suckage    /windows/C ntfs-3g noatime 0 0
>
> As you can see this even works for NTFS; you use the label you gave 
> the drive in Windows.
>
> After you've done these changes, it doesn't matter the least anymore 
> what the actual device name is.  You can even move the harddisk to 
> another computer (actually I'm doing exactly that) that totally 
> results in a re-ordering of /dev/sd* entries and it will still mount 
> correctly.
>
>
>

Question, if I were to label mine and then boot from a Gentoo or any 
other bootable CD, would those labels still be there?

Dale

:-)  :-) 

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Dale wrote:
> Nikos Chantziaras wrote:
>> Mick wrote:
>>> [...]
>>> What would be the recommended way of upgrading from the /dev/hd to 
>>> /dev/sd then?  I have held back doing this because I didn't have the 
>>> time to mess about with it.  If I were to configure a new kernel 
>>> without legacy ATA drivers, how would I know what my devices will be 
>>> seen as in advance, so that I can change my /etc/fstab before I reboot?
>>
>> The way I do it, is to label my partitions.  If your partitions aren't 
>> labeled yet, you can do so with 'tune2fs'.  If your /dev/hda1 is your 
>> root (/), /dev/hda2 your /home and /dev/hda3 your swap, you can label 
>> them with:
>>
>>   tune2fs -L GentooRoot /dev/hda1
>>   tune2fs -L GentooHome /dev/hda2
>>   mkswap -L GentooSwap /dev/hda3
>> [...]
> 
> Question, if I were to label mine and then boot from a Gentoo or any 
> other bootable CD, would those labels still be there?

The labels are part of the file system; they're always there.  For 
example, when booting the 2007.0 LiveDVD (which uses the legacy drivers, 
meaning /dev/hd* instead of /dev/sd*) the labels are there and I can 
mount /dev/disk/by-label/GentooRoot just fine.

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Dale]

Nikos Chantziaras wrote:
> Dale wrote:
>> Nikos Chantziaras wrote:
>>> Mick wrote:
>>>> [...]
>>>> What would be the recommended way of upgrading from the /dev/hd to 
>>>> /dev/sd then?  I have held back doing this because I didn't have 
>>>> the time to mess about with it.  If I were to configure a new 
>>>> kernel without legacy ATA drivers, how would I know what my devices 
>>>> will be seen as in advance, so that I can change my /etc/fstab 
>>>> before I reboot?
>>>
>>> The way I do it, is to label my partitions.  If your partitions 
>>> aren't labeled yet, you can do so with 'tune2fs'.  If your /dev/hda1 
>>> is your root (/), /dev/hda2 your /home and /dev/hda3 your swap, you 
>>> can label them with:
>>>
>>>   tune2fs -L GentooRoot /dev/hda1
>>>   tune2fs -L GentooHome /dev/hda2
>>>   mkswap -L GentooSwap /dev/hda3
>>> [...]
>>
>> Question, if I were to label mine and then boot from a Gentoo or any 
>> other bootable CD, would those labels still be there?
>
> The labels are part of the file system; they're always there.  For 
> example, when booting the 2007.0 LiveDVD (which uses the legacy 
> drivers, meaning /dev/hd* instead of /dev/sd*) the labels are there 
> and I can mount /dev/disk/by-label/GentooRoot just fine.
>
>
>

Keeeewl.  Now to see what I can screw up.  o_O

Dale

:-)  :-)

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Dale wrote:
> Nikos Chantziaras wrote:
>> Dale wrote:
>>> [...]
>>> Question, if I were to label mine and then boot from a Gentoo or any 
>>> other bootable CD, would those labels still be there?
>>
>> The labels are part of the file system; they're always there.  For 
>> example, when booting the 2007.0 LiveDVD (which uses the legacy 
>> drivers, meaning /dev/hd* instead of /dev/sd*) the labels are there 
>> and I can mount /dev/disk/by-label/GentooRoot just fine.
> 
> Keeeewl.  Now to see what I can screw up.  o_O

I should mention here the old Indian* saying: "If it ain't broke, don't 
fix it."


*OK, it's not Indian, but you get the idea.

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Dale]

Nikos Chantziaras wrote:
> Dale wrote:
>> Nikos Chantziaras wrote:
>>> Dale wrote:
>>>> [...]
>>>> Question, if I were to label mine and then boot from a Gentoo or 
>>>> any other bootable CD, would those labels still be there?
>>>
>>> The labels are part of the file system; they're always there.  For 
>>> example, when booting the 2007.0 LiveDVD (which uses the legacy 
>>> drivers, meaning /dev/hd* instead of /dev/sd*) the labels are there 
>>> and I can mount /dev/disk/by-label/GentooRoot just fine.
>>
>> Keeeewl.  Now to see what I can screw up.  o_O
>
> I should mention here the old Indian* saying: "If it ain't broke, 
> don't fix it."
>
>
> *OK, it's not Indian, but you get the idea.
>
>
>

True but I have trouble remembering which partition is home and which is 
portage, until I mount them anyway.  It's obvious then. 

I guess according to another reply that I will have to use something 
else for resierfs.  I guess it can't hurt to much.  Worst thing is to 
have to boot and edit fstab back to the old way.  :/

Dale

:-)  :-) 

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Dale]

Dale wrote:
>
>
> True but I have trouble remembering which partition is home and which 
> is portage, until I mount them anyway.  It's obvious then.
> I guess according to another reply that I will have to use something 
> else for resierfs.  I guess it can't hurt to much.  Worst thing is to 
> have to boot and edit fstab back to the old way.  :/
>
> Dale
>
> :-)  :-)
>

Well bummer, you have to umount it first.  O_O  That sucks.  Somebody 
tell me it ain't so.

Dale

:-)  :-)

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Dale wrote:
> Dale wrote:
>> True but I have trouble remembering which partition is home and which 
>> is portage, until I mount them anyway.  It's obvious then.
>> I guess according to another reply that I will have to use something 
>> else for resierfs.  I guess it can't hurt to much.  Worst thing is to 
>> have to boot and edit fstab back to the old way.  :/
> 
> Well bummer, you have to umount it first.  O_O  That sucks.  Somebody 
> tell me it ain't so.

It is so ;P

Best simply boot from the live CD and change the labels there, mount the 
root partition, change fstab right there and reboot.

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Mick]

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On Sunday 20 July 2008, Nikos Chantziaras wrote:
> Dale wrote:
> > Nikos Chantziaras wrote:
> >> Mick wrote:
> >>> [...]
> >>> What would be the recommended way of upgrading from the /dev/hd to
> >>> /dev/sd then?  I have held back doing this because I didn't have the
> >>> time to mess about with it.  If I were to configure a new kernel
> >>> without legacy ATA drivers, how would I know what my devices will be
> >>> seen as in advance, so that I can change my /etc/fstab before I reboot?
> >>
> >> The way I do it, is to label my partitions.  If your partitions aren't
> >> labeled yet, you can do so with 'tune2fs'.  If your /dev/hda1 is your
> >> root (/), /dev/hda2 your /home and /dev/hda3 your swap, you can label
> >> them with:
> >>
> >>   tune2fs -L GentooRoot /dev/hda1
> >>   tune2fs -L GentooHome /dev/hda2
> >>   mkswap -L GentooSwap /dev/hda3
> >> [...]
> >
> > Question, if I were to label mine and then boot from a Gentoo or any
> > other bootable CD, would those labels still be there?
>
> The labels are part of the file system; they're always there.  For
> example, when booting the 2007.0 LiveDVD (which uses the legacy drivers,
> meaning /dev/hd* instead of /dev/sd*) the labels are there and I can
> mount /dev/disk/by-label/GentooRoot just fine.

Yes, labels . . . been thinking of doing this for the last two years!  I guess 
I will have to use reiserfstune for my reiserfs partitions.  What about xfs - 
will xfsprogs do it?

Thanks for the tip.  The thing with the conventional device numbering system 
is that you know which one is first, which second, etc.  With Labels I'll 
have to add something to it to remind myself that this is the first 
partition, etc.  Can I have blank spaces in the Label name?
-- 
Regards,
Mick

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[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Mick wrote:
> On Sunday 20 July 2008, Nikos Chantziaras wrote:
>> The labels are part of the file system; they're always there.  For
>> example, when booting the 2007.0 LiveDVD (which uses the legacy drivers,
>> meaning /dev/hd* instead of /dev/sd*) the labels are there and I can
>> mount /dev/disk/by-label/GentooRoot just fine.
> 
> Yes, labels . . . been thinking of doing this for the last two years!  I guess 
> I will have to use reiserfstune for my reiserfs partitions.  What about xfs - 
> will xfsprogs do it?

The xfs_admin is used to change the label of XFS partitions: 
http://linux.die.net/man/8/xfs_admin


> Thanks for the tip.  The thing with the conventional device numbering system 
> is that you know which one is first, which second, etc.  With Labels I'll 
> have to add something to it to remind myself that this is the first 
> partition, etc.  Can I have blank spaces in the Label name?

I don't think spaces are allowed.  But you can use underscores or 
capitalization.  Anyway, you don't need to add something to remind you 
of the partition's position; /etc/mtab will use regular device names, so 
you can see what's going on with 'cat /etc/mtab' or simply 'mount' 
without parameters.  On my system, even though I use labels, I get this 
with 'mount':

   /dev/sdc1 on / type ext3 (rw,noatime)
   /dev/sda1 on /windows/C type fuseblk 
(rw,noatime,allow_other,blksize=4096)

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Neil Bothwick]

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On Mon, 21 Jul 2008 02:35:44 +0300, Nikos Chantziaras wrote:

> Anyway, you don't need to add something to remind you 
> of the partition's position; /etc/mtab will use regular device names,
> so you can see what's going on with 'cat /etc/mtab' or simply 'mount' 
> without parameters.

cfdisk also shows the labels against the partition names.


-- 
Neil Bothwick

Don't use a long word if a diminutive one will do.

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Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Nikos!

On Sun, Jul 20, 2008 at 12:29:19AM +0300, Nikos Chantziaras wrote:
> Alan Mackenzie wrote:
> >>The default in new kernels is to only use /dev/sd*.

> >I'm totally confused.  Doesn't "sd*" mean "SCSI disk drive"?  When I was
> >installing Gentoo from the CD, I had to mount my main hard drive as
> >/dev/sdb5.  When I built my own kernel, it needed /dev/hdh5.

> >This seems crazy.  Is it documented anywhere in Gentoo?

> Not sure.  But if you have /dev/hd* instead of /dev/sd*, it means you 
> configured your kernel with the legacy IDE drivers instead of the new 
> (P)ATA drivers.  The new drivers use /dev/sd* (for IDE/PATA/SATA and 
> SCSI alike; there's no difference anymore.)

This was indeed the case.

> The CD/DVD-ROM can show up as /dev/sd* even with the old legacy drivers 
> if you have enable "SCSI Emulation" for it.

> In any event, try to build a new kernel using the new drivers.  The old 
> legacy driver you're using will probably get declared "deprecated" at 
> some point (if it didn't happen already).

[ Detailed instructions snipped - but they were appreciated and followed
:-]

Did this.  It mapped my two hard drives (previously /dev/hd[gh]) to
/dev/sd[ab], and created /dev/sda, dev/sda1, .....  So far, so good.

However, it hadn't created /dev/sda16 or /dev/sda17 for some reason.  A
quick # ls -l /dev/sd{a15,b} gives:

... 8, 15  /dev/sda15
... 8, 16  /dev/sdb

In a philosophical mood, one might say that the new "unified",
"enhanced", "better" IDE support is inadequate for my setup.  What I
actually said, I'm not going to repeat in a public mailing list.

So the kernel guys have decided that nobody would ever want more than 15
partitions on a drive.  It's a bit like the old MS-DOS restriction to 512
MB all over again.  Hey, guys, hard drives nowadays are like 200 gig, not
512meg.  What's so wrong about having partitions with sizes 1Gb, 2Gb, 4Gb,
with maybe 100Mb for a boot partition?

>    < >   Generic ATA support

> unless you can't find a native driver for your chipset (I doubt you have 
> some extremely rare/exotic mainboard ;)

The HPT370A UDMA100 chip (with my two hard drives) was no problem.  For
the VIA VT82C586A/B/VT82C686/A/B/VT823x/A/C "ordinary" IDE chip (the one
with my two DVD drives attached), I tried configuring "VIA", which
didn't work.  Then I rebuilt the kernel again with "Generic ATA
support", which didn't work either.

Both of these created /dev/sdc and /dev/sdc1, but no /dev/sdd.  When I
tried # mount -t iso9660 /dev/sdc /cdrom, I got the "something's gone
wrong, but we're not telling you what" error message.  Trying to mount
/dev/sdc1 gave exactly the same result.  Actually, thinking about it,
this was probably my USB stick it was trying to access.

Nikos, do you happen to know the appropriate kernel mailing list where I
could express the opinion that restricting the number of partitions on a
drive to 15 isn't a good tradeoff?

All in all, I really amn't impressed with this "modern" drive support.
Besides quartering the max number of partitions on a drive, it confuses
IDE and SCSI drives, thus confusing me, too.  Previously, when I
attached devices to the IDE1 socket, I knew they would appear at
/dev/hd[cd].  Now, it would seem, the kernel assigns drives at random to
/dev/sd[abcd...], so you can only determine by experiment which devices
are at which "device".  Nothing personal, Nikos.  ;-)

I think I need to go back to the traditional IDE handling.

None of the Gentoo kernels I've built have even seen my two DVD drives,
yet.  I'll get there, somehow.

Thanks!

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Mick]

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On Sunday 20 July 2008, Alan Mackenzie wrote:

> So the kernel guys have decided that nobody would ever want more than 15
> partitions on a drive.  

From memory I recall that this has always been the limit for SATA/SCSI drives.  
For ATA drives I think it is 63?

Not sure if this is a Linux OS kernel restriction - what is the maximum number 
that MSWindows see?  I would think it is the same.
-- 
Regards,
Mick

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Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Mick,

On Sun, Jul 20, 2008 at 06:22:23PM +0100, Mick wrote:
> On Sunday 20 July 2008, Alan Mackenzie wrote:

> > So the kernel guys have decided that nobody would ever want more than 15
> > partitions on a drive.  

> From memory I recall that this has always been the limit for SATA/SCSI
> drives.  For ATA drives I think it is 63?

If I do # ls -l /dev/hd[gh], I get:

    brw-rw----  1 root disk 34,  0 2005-02-26 06:43 /dev/hdg
    brw-rw----  1 root disk 34, 64 2005-02-26 06:43 /dev/hdh

, which does indeed suggest a max of 63.  However, there's nothing on the
disk partition structure (which is basically a chain of extended
partitions across the entire disk) to limit this.

> Not sure if this is a Linux OS kernel restriction - what is the maximum number 
> that MSWindows see?

What's MSWindows?  ;-)

Proabably a lot less than 63.

However, the limit of 15 (which I didn't know about before) is a good
reason for me not to migrate to SATA disks.  I _like_ having lots of
partitions ~1 - 4 Gb.  It was trivial for me to clear a 4 Gb partition
for a trial installation of Gentoo (which, by the way, I'm expecting to
expand into my prime system - my Debian Sarge is beginning to feel very
tired).

Shoe horning IDE disks into the S{ATA,CSI}'s 15 partition limit seems an
unkind thing to do.

> Mick

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Neil Bothwick]

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On Sun, 20 Jul 2008 15:05:10 +0000, Alan Mackenzie wrote:

> So the kernel guys have decided that nobody would ever want more than 15
> partitions on a drive.  It's a bit like the old MS-DOS restriction to
> 512 MB all over again.  Hey, guys, hard drives nowadays are like 200
> gig, not 512meg.  What's so wrong about having partitions with sizes
> 1Gb, 2Gb, 4Gb, with maybe 100Mb for a boot partition?

Nothing, which is why the kernel includes LVM, allowing you to have many
more filesystems on a disk.


-- 
Neil Bothwick

c:>Press Enter to Exit

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[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Nikos Chantziaras]

Alan Mackenzie wrote:
> On Sun, Jul 20, 2008 at 12:29:19AM +0300, Nikos Chantziaras wrote:
>> The CD/DVD-ROM can show up as /dev/sd* even with the old legacy drivers 
>> if you have enable "SCSI Emulation" for it.
>> 
>> In any event, try to build a new kernel using the new drivers.  The old 
>> legacy driver you're using will probably get declared "deprecated" at 
>> some point (if it didn't happen already).
> [...]
> In a philosophical mood, one might say that the new "unified",
> "enhanced", "better" IDE support is inadequate for my setup.  What I
> actually said, I'm not going to repeat in a public mailing list.

I must admit that I'm not affected much by this since, as I mentioned in 
another post, I use labels and don't look at what /dev/sd* my drive is 
mapped.

For unpartitioned drivers where I'm not sure which /dev/sd* entry to 
use, I simply use /dev/disk/by-id instead ;)


> So the kernel guys have decided that nobody would ever want more than 15
> partitions on a drive.  It's a bit like the old MS-DOS restriction to 512
> MB all over again.  Hey, guys, hard drives nowadays are like 200 gig, not
> 512meg.  What's so wrong about having partitions with sizes 1Gb, 2Gb, 4Gb,
> with maybe 100Mb for a boot partition?

Unlike the above, this one is a real problem.  Fortunately, as long as 
the new drivers are still labeled "experimental" there's little chance 
of the legacy drivers being removed from the kernel.  Performance-wise, 
I don't think you're missing much by not using the new drivers (though 
that's just a guess; don't take my word on it :P)

If some day the legacy drivers are kicked out, you might have to go the 
LVM route by force :P  But I guess this isn't like to happen anytime 
soon now, since not all hardware seems supported by the new drivers.


> Both of these created /dev/sdc and /dev/sdc1, but no /dev/sdd.  When I
> tried # mount -t iso9660 /dev/sdc /cdrom, I got the "something's gone
> wrong, but we're not telling you what" error message.  Trying to mount
> /dev/sdc1 gave exactly the same result.  Actually, thinking about it,
> this was probably my USB stick it was trying to access.

I know that everyone is using his/her own system as he/she sees fit, but 
I don't mount CD/DVD and USB drives by hand anymore.  And no entries at 
all in fstab either.  I just plug it in and let dbus (+ HAL if you're on 
KDE/Gnome) handle the rest :P


> Nikos, do you happen to know the appropriate kernel mailing list where I
> could express the opinion that restricting the number of partitions on a
> drive to 15 isn't a good tradeoff?

LKML should be OK.  At least last time I checked, regulars there are 
against directing people to "more appropriate" lists, meaning that LKML 
is the most appropriate of all if the issue is about things that are 
officially in the kernel.

In any event, I remember this issue being raised back in 2004, so I 
guess it has been discussed to death by now.  (And I did not follow the 
discussion, so I can't give you a summary, I'm afraid.  Google is your 
friend.)


> All in all, I really amn't impressed with this "modern" drive support.
> Besides quartering the max number of partitions on a drive, it confuses
> IDE and SCSI drives, thus confusing me, too.  Previously, when I
> attached devices to the IDE1 socket, I knew they would appear at
> /dev/hd[cd].  Now, it would seem, the kernel assigns drives at random to
> /dev/sd[abcd...], so you can only determine by experiment which devices
> are at which "device".  Nothing personal, Nikos.  ;-)

I'm on PATA+SATA+USB here, so I know what you mean.  However, I found 
the /dev/disk/ tree to be very helpful here.

[gentoo-user] Solved!!! [Re: mount: "special device /dev/hdc does not exist"]

[Alan Mackenzie]

Hi, everybody,

I've got the problem fixed.  In my kernel config, I'd forgotten to
include a driver for my VIA "low speed" IDE controller.  I've put that
in, and I can now read CDs/DVDs (and probably burn them too).

I've stuck with the traditional /dev/hd[a-z] drivers for all the reasons
I've ranted about in other posts.

Thanks indeed to everybody who helped me get sorted!

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [gentoo-user] mount: "special device /dev/hdc does not exist". What does this mean?

[Daniel Pielmeier]

Alan Mackenzie schrieb:
> Hi, Gentoo?
> 
> I've a newly installed system, now working with my own special
> optimiesed keyboard layout.  :-)
> 
> However, I can't access my DVD drives.  I know at least one of them
> works, because I installed Gentoo from it.
> 
> When I do
> 
>    mount -tiso9660 /dev/hdc /cdrom
> 
> , it comes back with "special device /dev/hdc does not exist".  And yes,
> there was a CD in the drive, and /cdrom exists.

Do you mean

mount -t iso9660 /dev/hdc /cdrom

> What does "special device" mean here?  Does it mean the physcial
> hardware, the controller chip, the directory entry /dev/hdc, the driver
> in the kernel, or what?  What is "special" about my DVD writer?

It means the directory entry /dev/hdc.

> Well, to answer some of my questions, I was missing a /dev/hdc, so I
> made one with
> 
> # mknod /dev/hdc b 22 0
> 
> .  This didn't help one iota.  I had a look at dmesg, but there was no
> mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> drives are (don't ask!)).

Can't resist what is on hd{a-f}

> My kernel is an up to date linux-2.6.25-gentoo-r6.  I _think_ it's got
> all the needed options set in the configuration.  Can anybody suggest
> how to get my system to recognise my DVD drives?
> 
> Thanks in advance!
> 

What kind of DVD writer do you have maybe it is sata or scsi, and it 
wiil appear under /dev/srX or /dev/sgX. Or if you use the new libata 
library in the kernel even IDE devices are under /dev/srX or /dev/sgX.
-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Daniel

On Sat, Jul 19, 2008 at 09:11:09PM +0200, Daniel Pielmeier wrote:
> Alan Mackenzie schrieb:
> >Hi, Gentoo?

> >I've a newly installed system, now working with my own special
> >optimiesed keyboard layout.  :-)

> >However, I can't access my DVD drives.  I know at least one of them
> >works, because I installed Gentoo from it.

> >When I do

> >   mount -tiso9660 /dev/hdc /cdrom

> >, it comes back with "special device /dev/hdc does not exist".  And yes,
> >there was a CD in the drive, and /cdrom exists.

> Do you mean

> mount -t iso9660 /dev/hdc /cdrom

Maybe.  Is that different?

> >What does "special device" mean here?  Does it mean the physcial
> >hardware, the controller chip, the directory entry /dev/hdc, the driver
> >in the kernel, or what?  What is "special" about my DVD writer?

> It means the directory entry /dev/hdc.

OK.

> >Well, to answer some of my questions, I was missing a /dev/hdc, so I
> >made one with

> ># mknod /dev/hdc b 22 0

> >.  This didn't help one iota.  I had a look at dmesg, but there was no
> >mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> >drives are (don't ask!)).

> Can't resist what is on hd{a-f}

Nothing on hd[abef], a DVD writer on hdc and a DVD reader on hdd.  My PC
was built in 2001, and the 2 "onboard" IDE ports are "ordinary" IDE,
whereas the two IDE ports "stuck on the side" do UDMA66.

> >My kernel is an up to date linux-2.6.25-gentoo-r6.  I _think_ it's got
> >all the needed options set in the configuration.  Can anybody suggest
> >how to get my system to recognise my DVD drives?

> >Thanks in advance!


> What kind of DVD writer do you have maybe it is sata or scsi, and it 
> wiil appear under /dev/srX or /dev/sgX. Or if you use the new libata 
> library in the kernel even IDE devices are under /dev/srX or /dev/sgX.

No, the box is no longer young, and contains no SATA or SCSI bits at all.
I'm just going away to see if I've got any /dev/s[gr]X on the box. ....

No, I've got no /dev/s[gr]X at all.

Could it be that the kernel has looked at hd[ab], found nothing there,
and therefore decided "it's not worth the bother even looking at
hd[cd]"?

-- 
Alan Mackenzie (Nuremberg, Germany).

Re: [gentoo-user] mount: "special device /dev/hdc does not exist". What does this mean?

[Daniel Pielmeier]

Alan Mackenzie schrieb:
>>> When I do
> 
>>>   mount -tiso9660 /dev/hdc /cdrom
> 
>>> , it comes back with "special device /dev/hdc does not exist".  And yes,
>>> there was a CD in the drive, and /cdrom exists.
> 
>> Do you mean
> 
>> mount -t iso9660 /dev/hdc /cdrom
> 
> Maybe.  Is that different?
> 

Yeah, there is a space between -t and iso9660 :-)

> 
>> What kind of DVD writer do you have maybe it is sata or scsi, and it 
>> wiil appear under /dev/srX or /dev/sgX. Or if you use the new libata 
>> library in the kernel even IDE devices are under /dev/srX or /dev/sgX.
> 
> No, the box is no longer young, and contains no SATA or SCSI bits at all.
> I'm just going away to see if I've got any /dev/s[gr]X on the box. ....
> 
> No, I've got no /dev/s[gr]X at all.
> 
> Could it be that the kernel has looked at hd[ab], found nothing there,
> and therefore decided "it's not worth the bother even looking at
> hd[cd]"?
> 

Hmm, maybe the output of `dmesg`, `lspci -v` and `ls -al /dev` could be 
helpful. Probably also your kernel configuration.

[gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Miernik]

Alan Mackenzie <acm@muc.de> wrote:
> # mknod /dev/hdc b 22 0
> 
> This didn't help one iota.  I had a look at dmesg, but there was no
> mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> drives are (don't ask!)).

Maybe there was some /dev/sda /dev/sdb or something similar?
Why do you assume your drive is under /dev/hdx and not /dev/sdx ?

-- 
Miernik
http://miernik.name/

-- 
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Alan Mackenzie]

Hi, Miernik,

On Sat, Jul 19, 2008 at 09:13:09PM +0200, Miernik wrote:
> Alan Mackenzie <acm@muc.de> wrote:
> > # mknod /dev/hdc b 22 0

> > This didn't help one iota.  I had a look at dmesg, but there was no
> > mention of hdc in it.  (It did mention hdg, hdh, where my main hard
> > drives are (don't ask!)).

> Maybe there was some /dev/sda /dev/sdb or something similar?

There's /dev/sda and /dev/sda1, and no other /dev/sd*.  That's where my
UBS stick gets mounted.

> Why do you assume your drive is under /dev/hdx and not /dev/sdx ?

Er, because it's an IDE drive, and on my old Debian system it appears at
/dev/hdc.  My HDD is at /dev/hdh on both old Debian and new Gentoo.

When I do an lspci -v, on my Gentoo system, this shows up for hd[cd]:

00:07.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 06) (prog-if 8a [Master SecP PriP])
        Subsystem: VIA Technologies, Inc. VT82C586/B/VT82C686/A/B/VT8233/A/C/VT8235 PIPC Bus Master IDE
        Flags: bus master, medium devsel, latency 32
        [virtual] Memory at 000001f0 (32-bit, non-prefetchable) [size=8]
        [virtual] Memory at 000003f0 (type 3, non-prefetchable) [size=1]
        [virtual] Memory at 00000170 (32-bit, non-prefetchable) [size=8]
        [virtual] Memory at 00000370 (type 3, non-prefetchable) [size=1]
        I/O ports at a400 [size=16]
        Capabilities: [c0] Power Management version 2

This suggests that the IDE controller has been initialised properly, but
the kernel has ignored it.

> -- 
> Miernik
> http://miernik.name/

-- 
Alan Mackenzie (Nuremberg, Germany)

Re: [gentoo-user] Re: mount: "special device /dev/hdc does not exist". What does this mean?

[Graham Murray]

Alan Mackenzie <acm@muc.de> writes:

> There's /dev/sda and /dev/sda1, and no other /dev/sd*.  That's where my
> UBS stick gets mounted.

What about any /dev/sr*?