Re: vstafs installation

[Eric_Jacobs@fc.mcps.k12.md.us (Eric Jacobs) writes:]

>I did what you suggested; both files have the same size, but
>only the one copied from the dos partition will work correctly.
>But the things were even more bizarre that we had thought. The
>two files are identical up until just before the 128k mark. At that
>point vstafs had some garbage where dos has all zeroes. That was
>what you had thought in the last message. However, AFTER the 128k
>mark, they switch: vstafs has zeroes where dos now has data! Using
>my other friend, less, I see now that vstafs has zeroed out the string
>%$-+(,)*._~/<>|&^!:[, which contains the symbols that as was
>complaining about in my first message. To make things even weirder,
>the files sync up again shortly beyond that point.

This isn't as weird as it sounds. Just coincidentally, vstafs uses
contiguous buffers up to 64k in size to map onto the extents of a file. In
a virgin install onto vstafs, all files end up being entirely contiguous, so
vstafs buffers the file as 64k, 64k, and then a smaller fragment to cover
the end of the file. Variable sized buffers in the buffer cache was easily
the most complex part of vstafs, so no surprise that a bug has popped up
here.

>Also, I checked cp and it doesn't do any seeking. In fact, this problem
>seems to be created by doing nothing more than simple writes to
>vstafs. (pausing to go piddle on vsta machine.)
>The problem seems to have gone away. I did a cp back from the dos
>drive, and vstafs now has an uncorrupted version of as. Blah! I just
>sucessfully did a make.

Thank heavens. Wouldn't want an easy bug to hunt. :-)

>I still have the bad copy here, but I can't recreate the problem.
>:)

I've pawed through the file structure with vstafs/cmd/fsdb and no real
surprises. So it's in the R/W path in incremental file growth, probably. I
can probably recreate this by nuking my vstafs /vsta install, and then
reinstalling, but stopping right after the point where /vsta/bin/as goes in.

                                                                Andy
Received on Tue Oct 27 04:25:38 1998