SUN's response to SCSI disks > 669 MB

From: Michael S. Maiten (
Date: Fri May 24 1991 - 12:31:25 CDT

A SUN sales rep just sent the attached message to one of our clients.
He implies that even under OS 4.1.1 SCSI disks > 669 MB may have
troubles. This appears contrary to what has recently appeared on
sun-managers and what some vendors (not SUN) are claiming.

I believe from what I have found that these disks will work fine, so I
am surprised to see SUN claiming otherwise.

Does anyone have any *direct* experience where they have had problems
with big disks on SUNOS 4.1.1 ? (Or any others with experience to
show that there is no problem).

I will summarize and post the results.

Thank You!

Michael S. Maiten Internet:
Energetic Systems UUCP: ensys!msm
Telephone: +1 415 967-5538 (...!sun!bridge2!ensys!msm)

Private message sent from a SUN Sales Rep (sender's name removed):

A recent article in one of the more popular computer periodicals
discussed the problems on Sun desktops using SCSI disks greater
than 669 MB. I am concerned that my customers are being misled
by Sun VAR propoganda and have researched this problem myself
to better understand what the problem is and how it effects
my customers. Below is a summary of what I was told by the
engineering manager at Sun in charge of I/O products.

If you are not running SunOS 4.1.1 on your desktop and
are using SCSI disks greater than 669 MB, you are in trouble.

If you are running SunOS 4.1.1 on your desktop and using
SCSI disks greater than 669 MB, here is what to look-out for.

The problem described is currently not a feature under
SunOS 4.1.1, specifically the SunOS SCSI driver and format.dat.
The SCSI driver has never officially passed Sun internal QA
on the desktop using filesystems or partitions greater than
669 MB. If the disk becomes highly fragmented and/or full,
the SCSI driver may rewrite new data on top of existing data.
The format utility has never passed Sun QA formating BIG disks.
If defects and/or bad spots occur on these BIG disks after
performing the initial format of the disk, the format program
may not be able to fix these defects and/or rewrite the
bad block list on the disk with any accurracy.

In summary

        1. Its less of a risk running SunOS 4.1.1 on the desktop.

        2. The SCSI driver has not passed Sun QA using disks
           greater than 669 MB and partitions/filesystems
           greater than 669 MB on the desktop.

        3. If these BIG disks become highly fragmented and/or
           full, the SCSI driver may rewrite new data over
           existing data.

        4. The format utility may not format these BIG disks
           correctly and may not be able to fix defects and/or
           bad spots on these disks with any accurracy.


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