[Info-vax] Backup A Dying Disk.

[JF Mezei]

On 15-03-17 13:20, wa2flq wrote:

> I can mount the drive read only with error logging turned off, but trying to do a backup is painfully slow.

I am not sure there is anything you can do. The detection of problem
when reading a block is at the hardware level and it is the disk that
constantly retrying.

And you do not want to have error logging turned off. You want to see
the error count on the device and see how fast it rises. Error logging
simply captures errors reported by the hardware to go to logs, it
doesn't cause any difference in attempts at grabbing valid data.

Since you mentioned 5.5-2, I'll assume you don't have LD driver
installed (can it work on 5.5-2 ?)

RD54 is roughly 160 meg disk.  If you have that much storage available
on another drive, you can consider:

backup/physical/log dua0: disk:dua0_backup.save/save

also, capture the information from SHOW DEV dua0:/full

The advantage at this stage of the physical backup is that it will not
complain about file integrity which a normal backup might.

dua0_backup will be a file roughly the same size as the disk. If you are
able to bring this file to a more recent system with LD driver on, you
can create a virtual disk file with the EXACT same number of blocks as
what SHOW DEV got you, and LD CONNECT it with the same number of
cylinders, tracks and sectors, and then restore the physical backup.


The restoration  backup/physical/log dua0_backup.save/save lda1:  will
give you list of blocks which were in error and which may contain junk.

(you have to mount lda1/foreign before).

Once that is done, you can dismount lda1: and mount it normally, and
then ana/disk/repair etc to verify disk integrity.