[Info-vax] analyze/disk errors

[hb]

On 12/05/2013 05:16 PM, tadamsmar wrote:
> ANAL/DISK gave me a this warning ANALDISK-W-MAPAREA on BADBLK.SYS and some other files.

I don't know what analyze/disk is checking and what makes it issue such
a "warning". If the map area is invalid or even corrupted as
help/message states, then you usually can not get away with copying the
file contents: the map area describes the disk blocks containing the
file data. Ask your friend backup to restore the "some other files".

> ... So I tried to do copy it.  Copying worked on the other files, but I got an error when I tried to copy BADBLK.SYS....

Besides any map area problem, that's expected or the "nature" of
BADBLK.SYS: it contains/maps all the disk blocks which are not
guaranteed to be read. Mapping is done on the disk cluster base, so
there may be some good and some bad blocks. As far as I know, todays
disks do bad block replacement so, as long as that works, there should
not be real bad disk blocks in that file. But BADBLK.SYS may contain
"the end" of the disk. Consider a disk with 1000 blocks and a cluster
size of 3. Then BADBLK.SYS contains/maps one cluster, that is three disk
blocks starting at logical block number (zero based) 999. That's all
normal (no ANALDISK-W-MAPAREA) and expected as well as an error when
trying to copy such a BADBLK.SYS.

> So I made an image backup and restored the image from that backup and that cleared up the warning on BADBLK.SYS.

Because an image backup only contains the file header of the BADBLK.SYS
and a new BADBLK.SYS is created by backup when it restores the image
backup and implicitly initializes the disk (or by an explicit init
command if the restore is done with the /noinitialize).

And now, for fun, try to copy BADBLK.SYS to NLA0:. Any error?