will DVD/CD-ROM on internal Ultra 60 SCSI bus slow down disks?

will DVD/CD-ROM on internal Ultra 60 SCSI bus slow down disks?

Post by Griff Mille » Sun, 28 Oct 2001 00:20:53



% cdrecord -scanbus
Cdrecord 1.11a01 (sparc-sun-solaris2.6) Copyright (C) 1995-2001 J?rg Schilling
Using libscg version 'schily-0.5'
scsibus0:
        0,0,0     0) 'SEAGATE ' 'ST336704LSUN36G ' '0326' Disk
        0,1,0     1) 'SEAGATE ' 'ST336704LSUN36G ' '032C' Disk
        0,2,0     2) *
        0,3,0     3) *
        0,4,0     4) *
        0,5,0     5) *
        0,6,0     6) 'TOSHIBA ' 'DVD-ROM SD-M1401' '1007' Removable CD-ROM
        0,7,0     7) HOST ADAPTOR
scsibus1:
        1,0,0   100) 'IBM     ' 'DDRS-39130D     ' 'DC1B' Disk
        1,1,0   101) *
        1,2,0   102) *
        1,3,0   103) *
        1,4,0   104) 'HP      ' 'C1533A          ' 'A907' Removable Tape
        1,5,0   105) *
        1,6,0   106) *
        1,7,0   107) HOST ADAPTOR

The unit at 0,6,0 is a Sun X6168A .  It has the usual 50 (54?) pin
ribbon cable connector, instead of 68 or 80 like the faster SCSI
buses require. I'm not saying I ever saw a 68/80-pin CD/DVD-ROM
drive - just that I know that e.g wide-SCSI drives use 68/80.

Does this mean it will slow down the bus to
some lowest common denominator, thereby limiting the disks at 0,0,0
and 0,1,0 ?

Or, just forget my explanation for worrying about this - I may be worrying
about the right thing for the wrong reasons - and tell me (please)
if adding a CD/DVD-ROM drive to the internal bus of an Ultra 60 will
slow down the internal disks on the internal bus.

Thanks! Email cc's appreciated.

--
Griff Miller II                   |                                           |
Manager of Information Technology | "I need to be the owner of all of         |
Positron Corporation              |  the files in /usr/kvm."                  |

 
 
 

will DVD/CD-ROM on internal Ultra 60 SCSI bus slow down disks?

Post by Joerg Schilli » Sun, 28 Oct 2001 01:05:17




Quote:>% cdrecord -scanbus
>Cdrecord 1.11a01 (sparc-sun-solaris2.6) Copyright (C) 1995-2001 J?rg Schilling
>Using libscg version 'schily-0.5'
>scsibus0:
>        0,0,0     0) 'SEAGATE ' 'ST336704LSUN36G ' '0326' Disk
>        0,1,0     1) 'SEAGATE ' 'ST336704LSUN36G ' '032C' Disk
>        0,2,0     2) *
>        0,3,0     3) *
>        0,4,0     4) *
>        0,5,0     5) *
>        0,6,0     6) 'TOSHIBA ' 'DVD-ROM SD-M1401' '1007' Removable CD-ROM
>        0,7,0     7) HOST ADAPTOR

>The unit at 0,6,0 is a Sun X6168A .  It has the usual 50 (54?) pin
>ribbon cable connector, instead of 68 or 80 like the faster SCSI
>buses require. I'm not saying I ever saw a 68/80-pin CD/DVD-ROM
>drive - just that I know that e.g wide-SCSI drives use 68/80.

NO, SCSI will not slow down the bus. However, as it may be that the
drive simply occupies the bus for some time that might be longer
that the time used by a harddisk, it may be that a slight slow down
is noticable when you heavily use the drive while HD transfers are
running.

--



URL:  http://www.fokus.gmd.de/usr/schilling    ftp://ftp.fokus.gmd.de/pub/unix

 
 
 

will DVD/CD-ROM on internal Ultra 60 SCSI bus slow down disks?

Post by Griff Mill » Sun, 28 Oct 2001 08:09:51



> NO, SCSI will not slow down the bus. However, as it may be that the
> drive simply occupies the bus for some time that might be longer
> that the time used by a harddisk, it may be that a slight slow down
> is noticable when you heavily use the drive while HD transfers are
> running.

OK, thanks, Joerg. That makes me feel better. I really didn't think Sun
would do something that would make it easy or typical for people to hamper
the internal bus. After all, just about everyone would install a CD/DVD-ROM
drive in the internal bay of an Ultra 60)

I just have this memory (maybe a wrong one) that mixing narrow SCSI
components with wide leads to a performance degradation. Perhaps
I am thinking of wide components on a narrow bus. That obviously
would cause the wide components to run below their potential. But
narrow components on a wide bus, that's doesn't slow down any wide
components that may be on the same bus? Or are the X6166A/X6168A
(what is typically used for CD/DVD-ROM in an Ultra 60) in reality wide
components even though they use the 50-or-so-pin ribbon connector?

Come to think of it, the Yamaha 8424S CD-R/RW is called wide, even though
it uses the ~50-pin connector.

See, you've reassured me, but now I want to know why that reassures me.  :)
There's just no pleasing some people.

Thanks again!

--
Griff Miller II                   |                                           |
Manager of Information Technology | "Do Lipton employees take coffee breaks?" |
Positron Corporation              |                                           |

 
 
 

will DVD/CD-ROM on internal Ultra 60 SCSI bus slow down disks?

Post by Anton Ran » Wed, 31 Oct 2001 02:36:19



> scsibus0:
>         0,0,0     0) 'SEAGATE ' 'ST336704LSUN36G ' '0326' Disk
>         0,1,0     1) 'SEAGATE ' 'ST336704LSUN36G ' '032C' Disk
>         0,6,0     6) 'TOSHIBA ' 'DVD-ROM SD-M1401' '1007' Removable CD-ROM

> The unit at 0,6,0 is a Sun X6168A .  It has the usual 50 (54?) pin
> ribbon cable connector, instead of 68 or 80 like the faster SCSI
> buses require.  [...]  Does this mean it will slow down the bus to
> some lowest common denominator, thereby limiting the disks at 0,0,0
> and 0,1,0 ?

Possibly in part.  If the drives are LVD (low-voltage differential),
and your host adapter supports LVD, then attaching a single-ended (SE)
DVD-ROM drive will force the bus into the lower-performing SE mode.

However, I believe that the Ultra-60 ships with a single-ended host
adapter.  In this case, keeping the DVD on the same bus doesn't hurt
(except when it's active and competing with the drives for the bus).

-- Anton (not speaking for Sun)

 
 
 

1. Speeding Up or Slowing Down an Ultra 10 with SCSI Drive and CD-ROM?

I've obtained an Ultra 10 with a 440 MHz CPU and an Antares P-0061 PCI
SCSI host adapter. The host adapter has one interior 68 pin connection and
one exterior, also 68 pin. An 18 GB Seagate SCSI drive is connected
internally.

I'd like to remove the IDE CD-ROM drive and replace it with a Plextor
PX-40TSUWi SCSI CD-ROM.

Will the CD-RM slow down the system since it will be on the same cable as
the hard disk?

Would a different host adapter with two internal connections be a better
choice. If so, what brand and model would be recommended?

Thank you,

Erik Jensen

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