RA81/UDA50 tools for 4.2?

[r. stork]

> Are there any tools to allow updating of revectoring info
> for RA81/UDA50? When a new sector goes bad it should be added
> to the map with a relatively simple user-level program, maybe
> with some ioctl() calls to the driver.
> 
> The only method our DEC reps can suggest is reformatting of the
> whole disk, after which yours truly has to restore everything
> form tape, which takes forever!
> 
> Any insights will be appreciated!
> 
> vax135!gc

You should have your DEC reps contact their next level of support
for the correct procedures on dealing with the problem.  The approach
they are using is the ABSOLUTE worst way to deal with the problem.
The reasons for this are due to the DSA Architecture.  Each RA81 has
a set of tables containing the bad spots found at manufacturing time.
When the drive is formatted these tables are copied into another set
of drive tables (working area).  The DEC CE's have no tool to change
the manufacturing table.  Any bad spots found in formatting will be
added to these tables. If you are running VMS or have hacked Bad
Block Revectoring into your disk driver, this working area will 
dynamically grow as the operating system finds bad spots and retires
them in favor of alternates (either on track or not).  Good so far.

One problem is that the current DEC formatting tool is a non-exhaustive
formatter that will not find all the bad spots.  They assumed that
everyone would have BBR and DSA systems so no more powerful tool
was needed in the field.
The problem is that BBR is not in all flavors of UNIX, so when a new
bad spot appears, you do your dump to tape, they re-format, and
you restore, to the ORIGINAL manufacturers list of defects plus whatever
the formatter finds.  So now you likely will get all kinds of bad
spots back.

There is no good solution except to have BBR on your system, but here
is a hack that will work.  Boot up under VMS, and create a VMS filesystem
that fills up the entire RA81.  Write a little program that fills is up
completely with files.  File size should be about 64KB.  Let this thing
run overnight (12 hours, but you only do it once).  Now run analyze
on the VMS filesystem you build.  This reads each file on the disk.  
VMS will find the bad spots and re-vector them for you.  Do it again
since it only takes an hour.  You now have a logically free disk.
Dump the filesystem to tape (30 Minutes) and save them.  Now boot
up UNIX and put your filesystem out on disk.  Your problem is solved.
The RA81` will use the tables just filled by VMS and will work fine
until a new bad spot appears.  
	When that happens simply dump your UNIX filesystem to tape
as before, boot VMS and read-in the tape you made, run analyze once
and restore your filesystem.
	This is the approach that we are using with Ra81's in my
lab.  It was developed after discussions with the RA81 project
manager and several of DEC's technical support people.  By the way,
the DEC CE's did most of the VMS stuff, and keep several copies
of the tapes in all the Chicago offices serving RA81's.
	All of the CE's in our area working on Ra81's were told
NOT to format them except when the read/write board or datapath
interface board had gone bad.  This could then cause the bad
spot tables(FCT I think.) to fill up with many bad spots and
hence slow down the drive due to re-vectoring.
	One last point, DEC has promised that a new diagnostic
will soon be available to allow the CE's to at least read the
status of the drive internal tables.
	Hope this helps.

						Ron Stork
						ihlpl!rfs