CD Changer

CD Changer

[Alexandre April]

	I need to be able to export all 4 of my CDR-251 4x4 CD Changer
using NFS or SAMBA. I found some way to do it but never been able to
accomplish it, cause of older kernel. I'm running on a 2.4.18-14 kernel.

	Any idea how ?

	Alex

Re: CD Changer

[Randy.Dunlap]

On Sun, 19 Jan 2003, Alexandre April wrote:

| 	I need to be able to export all 4 of my CDR-251 4x4 CD Changer
| using NFS or SAMBA. I found some way to do it but never been able to
| accomplish it, cause of older kernel. I'm running on a 2.4.18-14 kernel.
|
| 	Any idea how ?

The only CD changer patch I know of is for 2.2.x.
Did you already look at this?
  http://unfix.org/projects/changer/

-- 
~Randy

Re: CD Changer

[Alexandre April]

I'm using kernel 2.4.x and to be able to use that patch I'll have do modify
some compatibility issue, and I don't have time righht now to to that !

Alex

----- Original Message -----
From: "Randy.Dunlap" <rddunlap@osdl.org>
To: "Alexandre April" <alexandre.april@sympatico.ca>
Cc: <linux-kernel@vger.kernel.org>
Sent: Sunday, January 19, 2003 11:28 PM
Subject: Re: CD Changer


> On Sun, 19 Jan 2003, Alexandre April wrote:
>
> | I need to be able to export all 4 of my CDR-251 4x4 CD Changer
> | using NFS or SAMBA. I found some way to do it but never been able to
> | accomplish it, cause of older kernel. I'm running on a 2.4.18-14 kernel.
> |
> | Any idea how ?
>
> The only CD changer patch I know of is for 2.2.x.
> Did you already look at this?
>   http://unfix.org/projects/changer/
>
> --
> ~Randy
>
> -
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> Please read the FAQ at  http://www.tux.org/lkml/

Re: CD Changer

[David D. Hagood]

Alexandre April wrote:
> I'm using kernel 2.4.x and to be able to use that patch I'll have do modify
> some compatibility issue, and I don't have time righht now to to that !

The problem is that Linus did not see fit to make the IDE changer code 
present an IDE changer as multiple block devices, as a SCSI changer is. 
As a result, you cannot mount each disk in the changer seperately - all 
you have is a tool to change which disk is accessed by the single block 
device.

Linus's stated position is that since a disk change takes a fair amount 
of time, in a situation where multiple users are accessing different 
disks the system could thrash between the disks and go nowhere, slowly. 
If you search old LKML posts of about three years ago you should be able 
to find his exact post.

Now, I would dispute the logic, since the SCSI changer behavior is 
identical - I have both a SCSI changer and an IDE changer, and the SCSI 
changer will thrash if multiple processes are accessing different disks. 
Since SCSI does it, I see no reason why IDE cannot be allowed the same 
behavior. However, it's called "Linux" not "Davix"...

However, given that you can buy a 120G drive for US$120 or so, a changer 
has a lot less utility now-a-days. Just buy a cheap hard disk and copy 
the CDs onto it. That way, you have faster access, switch time is 
eliminated, and wear-and-tear on the disks and the changer are eliminated.

You could even DD the disk to a file, and mount that file as an ISO9660 
file system using loopback, thus preserving all the "CD-ishness" of the 
data.

Even if users wish to change disks - you can store a lot of disks in 
120G of storage - just copy the disk over and mount the copy.

Re: CD Changer

[Jan-Benedict Glaw]

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On Sun, 2003-01-19 16:30:12 -0500, Alexandre April <alexandre.april@sympatico.ca>
wrote in message <002c01c2c001$f36db9f0$0a01a8c0@aaprilhome>:
> 	I need to be able to export all 4 of my CDR-251 4x4 CD Changer
> using NFS or SAMBA. I found some way to do it but never been able to
> accomplish it, cause of older kernel. I'm running on a 2.4.18-14 kernel.

I used to use a 7way CD-Changer (a SCSI model) over years. It's quite
simple, no patches requited. I simply had to switch on "Scan all LUNs"
in kernel's config. Then, all four slots appear as separate devices so
you can mount them all (in parallel) and share them (by NFS/SMB/...).
However, because there's actually only one CD drive inside the box,
persormance suck mountains is you access two (or more) CDs at a time,
because they're constantly swapped...

MfG, JBG

-- 
   Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481
   "Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur
    fuer einen Freien Staat voll Freier Bürger" | im Internet!
   Shell Script APT-Proxy: http://lug-owl.de/~jbglaw/software/ap2/

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Re: CD Changer

[Alexandre April]

Does it work for IDE CD changer as well ?

Alex

----- Original Message ----- 
From: "Jan-Benedict Glaw" <jbglaw@lug-owl.de>
To: <linux-kernel@vger.kernel.org>
Sent: Monday, January 20, 2003 2:23 AM
Subject: Re: CD Changer

Re: CD Changer

[Jan-Benedict Glaw]

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On Mon, 2003-01-20 07:56:31 -0500, Alexandre April <alexandre.april@sympatico.ca>
wrote in message <00d201c2c083$5aceb460$0500000b@shiva.com>:
> Does it work for IDE CD changer as well ?

Well, they don't exactly have "LUNs", as this is a SCSI thing. You'd
possibly try the ide-scsi module on it, though. Basically, _all_ CD-ROM
drives are (based on their commands) SCSI devices controlled over an IDE
bus. Maybe ide-scsi works here...

MfG, JBG

-- 
   Jan-Benedict Glaw       jbglaw@lug-owl.de    . +49-172-7608481
   "Eine Freie Meinung in  einem Freien Kopf    | Gegen Zensur
    fuer einen Freien Staat voll Freier Bürger" | im Internet!
   Shell Script APT-Proxy: http://lug-owl.de/~jbglaw/software/ap2/

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: CD Changer

[Alexandre April]

    Well I tried using ide-scsi for the CD changer device but without your
"Scan all LUNs" and it showed only one device so I suppose if I turn that
switch on I'll probably gonna see all 4 cd in different LUNs.

    Do you have the exact swicth for Scan all LUNs ?

    Alex
----- Original Message -----
From: "Jan-Benedict Glaw" <jbglaw@lug-owl.de>
To: <linux-kernel@vger.kernel.org>
Sent: Monday, January 20, 2003 8:19 AM
Subject: Re: CD Changer

Re: CD Changer

[Markus Plail]

* Alexandre April writes:
>Well I tried using ide-scsi for the CD changer device but without your
>"Scan all LUNs" and it showed only one device so I suppose if I turn
>that switch on I'll probably gonna see all 4 cd in different LUNs.

>Do you have the exact swicth for Scan all LUNs ?

[plail@plailis_lfs]grep LUN /usr/src/linux/.config
# Some SCSI devices (e.g. CD jukebox) support multiple LUNs
# CONFIG_SCSI_MULTI_LUN is not set

SCSI support -> Probe all LUNs on each SCSI device

HTH
Markus