From:	TAPE::SENEKER      "Rob Seneker" 10-JUN-1996 10:16:28.48
To:	STAR::EVERHART
CC:	ME
Subj:	RE-2: WORM support in OVMS via OSMS

Glenn,

Thanks for your response.

I really need to get together with you and discuss the combination
of what you have done with what OSMS needs.   Here are some additional
comments/questions from your mail.

>>> I did ...  design work ... Virtual Branches

I did not know you did the Virtual Branches work.

>>> I designed it before coming to DEC and even started coding it...

Before coming to DEC?  Where from, how long ago?

>>> when you tell an optical to overwrite data, what happens?

It depends on the way the manufacture implements the drive.  Some return
an error and do nothing, and some revector the data to another block, and
I beleive that some do a destructive overwrite after which the block is
garbage.

>>> If you do a "replace block" command, is that sufficient to replace blocks
>>> that are to be overwritten?

On the drives that I thought this would be possible, they did not seem to
have enough "replacement blocks" to allow for file system use and the true
replacement needed for bad blocks on the media.  You are correct that the
Perceptics code did not try to use any of this.  I think it would be worth
investigation but I think a manufacture would have to work with a file
system design group to make sure everything worked ok, mainly the amount
of replacement blocks available and the placement of the replacement areas
on the disk so performance does not go down the drain.

I agree that if the "replacement block" method would or could be used so
the use of WORM disks would be very straight forward.

>>> If worms-11 is in fact a complete ACP,...

Yes, it is a complete ACP, but currently it doesn't do any locking so that
would have to be added.

>>> my other question is whether worms-11 is used for r/w opticals?

No, worms-11 is only used for WORM, I use it on R/W optical for testing
but the customers generally do not have a need for this.

I am currently working on getting the current code base brought into
Digital, documented, and producing another release to address some bug
fixes, V7.0 support, and some new RWxxx series hardware.  They want this
by the end of July.  After that the big push is going to be trying to
get a WORM solution on Alpha in time for the 7.1 release.  This is
something else I would like to talk to you about and it needs to be soon
if possible.

When is a good time to call you or you call me.  After that if your
interested maybe we can get together in person.

Thanks,
Rob Seneker

508 841 2782
DTN: 237 2783,  I think the 237 part is right, I am in Shrewsbury, MA.