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CDROM Problems Sun CD+ CDU-561(& others?)512 vrs 2048 bytes

I have Sun SS1's and LX computers and Sun CD+ external CDROM's; a Sony CDU-561. I have posted problems and questions before as to why I could boot from the CD, but the install would fail with error messages that the CD could not be mounted or was already mounted. I received no replies. I searched the old Dedian lists and found a similar complaint (problem) with no solutions offered. I emailed  John who ahd the same problem and his reply follows;
Hello Peter,

I could not figure out why this Sony cdrom would not read the cd's
correctly.  So, I changed out the cd with another one.  Later,
I used the troublesome sony cdrom in an intel windows box.  The cdrom
worked there for a while and then it quit reading altogether.  
So, I bought a new scsi cdrom and threw away the sony one.

For what its worth, I bought the sony cdrom on ebay in a used item sale.
I think because the unit was used, there was something wrong with it.  I
don't think the problems were due to the debian install cdrom.

On a related note, I purchased a sparc 5 with a built-in cdrom.  I had
similar errors with its cdrom.  I sent the cdrom back to the 
dealer in exchange for a new cdrom.  The new cdrom works flawlessly.  So
far, I have not had any errors.

A search of the following FAQ's listed below
CD-ROM Drives on Sun Hardware     http://www.aball.de/~wpv/sun/faq/cdrom.html  and  Sun CD-ROM FAQ http://saturn.tlug.org/suncdfaq/
stated The Sony inside will accept the  SCSI MODE SELECT command command and switch to 512 byte mode. While mounting and initializing, it will complain, but will work. In the early days of Sun Microsystems workstations, the CD-ROM drive requirements were very strict. That is, in order for any CD-ROM drive to function on a Sun workstation, it either had to be made/marketed by Sun or support a 512 byte block size. Since third-party CD-ROM drives were often much cheaper than those sold by Sun, curious users started investigating the use of generic CD-ROM drives as opposed to those branded by Sun. It was soon discovered that, in fact, most drives on the market at the time did not work with Sun hardware and as such this FAQ was born in an effort to educate.

My work around found by accident and frustration after John's email I decided to make a HOT CHANGE  of one external CDROM for another. All of a sudden the SUN would read the CD it had refused to read but had just booted from. I've experimented with about 15 installs in the last week and all I HAVE TO DO IS TURN THE POWER OFF THEN BACK ON on the external CDROM. Sometimes this takes a couple of cycles or ejecting the CD and a couple of times a shutdown and cold reboot. I assume this has the effect of SETTING THE MODE SELECT in the proper mode.

I guess this is not a major problem as most people are using newer CDROM's. The FAQ's list many other old CDROM's that have the same problem and solutions. Since a CDROM install is not needed very often I'll stick with turning the power off and on for now.

Hope this helps a few others, it has taken over two months to sort out!

Peter Myers

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