Low Level Format

From: Fred Cisin <cisin_at_xenosoft.com>
Date: Thu Aug 21 17:25:01 2003

> >If the LLF is not performed on IDE drives,
> >then I wonder wonder what Format does spend its time on?

On Wed, 20 Aug 2003, Joe wrote:
> That's a good question. However there's a LOT of clusters on a modern HD
> and it has to create FAT entries for all of them (actually TWO FATs) plus
> create a directory. Perhaps it writes and verifies those areas of the drive
> but not the data area.

It definitely does write all of the directory area (boot record,
FAT(s), DIR).
If the /Q option is active (now default?) then that is ALL that it does.
If /U is active, then it at least "VERIFIES" every cluster.

Please note: no matter what is misstated in a lot of manuals,
"VERIFY" does NOT compare the contents with what it should be!
"VERIFY" consists of nothing more than confirming that the CRC
of the data in the sector matches the CRC recorded in the header
of the sector.
I once had a malfunctioning floppy drive that would read,
but not write. ALL DOS operations claimed to be successful,
since it would NOT write, and then would successfully VERIFY
the contents of the sector that it did not write.

That's why in XenoCopy, I had both a VERIFY, and a COMPARE.

> But as Gene or Fred pointed out, a LLF format on the OLD MFM drives with
> only 100 or 200 Mb or so took 12 plus hours to run. Imagine what it take

That was another Fred. But he was talking about how long SPINRITE took.
LLF is a lot faster, but still a long time.

For LLF, I think that Speedstor is a LOT better.
SPINRITE is good for trying to recover stuff that has a lot
of read errors.

One of the issues about SPINRITE was Gibson's attitude about
relative validity of manufacturer v field testing. He actually
believed that if the manufacturer said a sector was bad, but
that it read and wrote successfully, that it should be
"returned to service"! He later backed down on that, and
stopped making that the default. I figure that if the
manufacturer said, "don't trust this sector", that they would be right.

> >I mean, on floppies a HLF takes about a second.
> Then your system is a LOT faster than any I've seen. It takes at least a
> minute (ball park,I haven't timed it) on all that I've seen.

You ar right.
A REAL format is, indeed, at least a minute. But the /Q option
of FORMAT causes it to do nothing more than write a blank DIRectory,
which IS just seconds.

Grumpy Ol' Fred     		cisin_at_xenosoft.com
Received on Thu Aug 21 2003 - 17:25:01 BST

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