Q how do you patch a 4.2 filesystem, to make it smaller

[Sohail M. Hussain]

We just finished upgrading from 4.1 BSD to 4.2
and I just noticed a problem with our users filesystem.
We have all our users on a ra81, and i made the file
system using "newfs ra0f ra81". That caused a file system
of size 478582 blocks to be created starting some where in
the middle of the disk, and going to the end.

After making the filesystem I did a "restore r" to read in the
old data from the 4.1 dump tapes. The did a "fsck /dev/ra0f" and
fsck complains about being "unable to read block 478580".

Futher investagation shows that blocks 478580, 478581 cannot be read.

I have tried changing the value of "fs_size" in the super block, and then
running fsck, but the 4.2 fsck is smarter than the 4.1 fsck, and it changed
the value back to the original. I also tried changed both "fs_size" and
"fs_dsize", but then fsck really complains.

So my question is how can get 4.2 to not look at those 2 blocks.

Any advice would be welcome, since the only alternative i can see is
writting out to tape, rebuilding the partition, and reading back again.
Since with tu80 drives this would take about 9-10 hours, (on a weekend too)
I would like to avoid doing that.


Thanks in advance for you consideration.

Sohail.
-- 
Sohail Hussain

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