On Thu, 29 Jan 2004 10:13:03 -0500, Terry King
wrote:
Spirit's computer system, its flash memory bogged down by too many data
files, began a continuous series of resets. Contact with Earth was lost
for a time.

IOW, they tried to store another file they thought would fit, and it
didn't, and the master program didn't do anything more intelligent
than reboot.

Now, controllers have managed to get a better handle on their $400
million spacecraft to find the exact source of the problem and delete old
files that aren't needed.

"We are attempting to get a trace from the flight software of the problem
and compare that to what we believe it to be, what we have seen in the
testbed, make sure we are correct and then move forward in deleting some
of the files from our flash file system as a result of understanding the
problem," mission manager Jennifer Trosper said Wednesday.

"We are extremely careful because we want to make sure that we don't make
an error in deleting files. The we have done file deletes on the
spacecraft before, so we've shown that does work. The file directories
have all different names and you can convince yourself that you are
actually deleting the right thing."

I suppose they never heard of internal fragmentation, block size, and
stuff. I don't know the details either, but flash memories apparently
fragment badly, don't reclaim individual sectors as well as your
average Windows disk directories. Eventually you have to reformat the
flash like reformatting a disk to get contiguous room. It sounds like
they didn't know that. If, indeed, the flash memory is even the root
of the problem.

"We will attempt the surgical technique about one more day. If that
doesn't work, we will move forward to the less-surgical techniques. And
hopefully if we are on the right track we would hope at the earliest be
back doing science early next week. If we're not on the right track, it
could take longer than that."

I hope that this flash/files program is the whole problem, but if so,
it still sounds like they never did any serious system test, not to
mention missing some important design rules from the start. The "less
surgical" technique would be "delete all files" as on any digital
camera. Very sophisticated.

--

All of the above is speculation based on nothing but the public news.

J.