The Question is:
I have a MicroVAX 3100-95 system with two SCSI channels attached to two BA356's
containing both wide and narrow disks. Recently, the system failed to boot
from the System disk reporting an illegal disk structure. On booting the
system from a backup copy,
I discovered several of the disks on both channels reported "primary home block
is bad". I repaired these using Analayze/Disk but am a little concerned that a
system disk that looses the primary home block fails to boot. Do you haver any
ideas why this wo
uld have happened?
Thanks in Advance.
The Answer is :
It is possible that this can be caused by a system or storage hardware
problem, or by (privileged) software scribbling on the disk, or by a
power failure at an inopportune moment during a multi-block transfer,
or by configuration and/or latent problems with (privileged) layered
products acting as adjuncts to the OpenVMS file system. (eg: disk
defragmentation or I/O caching tools.) No specific cause can likely
OpenVMS can and does use alternate disk home blocks when necessary.
The OpenVMS Wizard will assume that you have also reviewed your system
data archiving policy and have investigated the validity and particularly
the restorability of any archival mechanism(s) in use. The OpenVMS Wizard
will also assume that volume shadowing (RAID) has been considered -- while
RAID will not prevent privileged applications from scribbling, shadowing
can be useful in avoiding disk-related (hardware-level) errors.