On 3/5 I posted a query about a lost disk label and a breif
summary of the configuration.
There were two trains of thought on the solution of the problem. The
first was that there may be a problem with the disk, the second that
there is an application overwriting the disk label, which more closely
portrayed my situation. Here is a summary of responses from
Sun-Managers on the situation.
POTENTIAL DISK TROUBLE:
There firmware may be an older revision, and since updated against this
type of problem.
Several reports of problems with early revisions of the xd controller
were reported I did'nt get any bug id's & haven't contacted sun yet)
THE LOCATION OF THE DISK LABEL:
Unix is intelligent in that it will not use the very beginning of a
disk partition "for a Unix file system". The disk label is in cylinder
0, the very beginning of the disk, normally the start of the "a" and
"c" disk partitions.
The problem of a lost label arises when an application that uses an
entire partition writes to the beginning of a disk partition.
Three examples of this violation were noted: Sybase, swapping and
Ingres. Each of these "applications", when given a disk partition to use
in its own manner will happily write from edge to edge of the disk
Therefore the use of a partition including cylinder 0 for a non-Unix
filesystem may allow aplications to overwrite the disk label, depending
on the application and luck.
The message here is "do not use cylinder 0 for anything if it is not
included in a normal Unix file system.
It was also pointed out that this type of warning appears in the sun
manual set, but I have yet to find where, and it is also warned about
on page 3-5 of the Sybase installation manual. (Hey, they asked me for
a partition & I gave it to them, I screwed up ... never trust the
applications programmers ;-)
I now have to question what is the preferred fix to the disk label
problem. I can easily :
- start the "a" partition at cylinder 1 and leave the 0 cylinder
excluded from any partitions.
- make a tiny "a" partition including cylinder 0 and make another
partition starting at about cylinder 4 for sybase.
(In the mean time I just re-labeled the disk since this is a low
occuring problem ... 2x in 5 months)
I got so many responses that I could not reply to each one for thanks, so
here is a thanks to the following responders for the speedy help!
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:05:56 CDT