Re: vfat and SECTOR_SIZE=2048

From: Tigran Aivazian (tigran@sco.COM)
Date: Tue Jan 11 2000 - 04:32:19 EST


On Tue, 11 Jan 2000, Daniel Kobras wrote:
> Which kernel version are you referring to?
2.3.39 (well I was looking at 2.3.39-pre2 but now only work with 2.3.39)
Note that I was just reading code and not actually mkfs-ing any dos
filesystems on MO devices.

> I haven't tested with 2.3 so far, but mainly because vfat (well, actually
> it's the fat part we're talking about) is painfully slow on MO media.

Hmmm, it is not painfully slow on MO media using UnixWare7 dosfs. But I
haven't run any benchmarks to compare so it probably depends on what you
mean by "painfully slow".

> What
> makes you think it's broken? Have you had a look at the comment in
> bigblock_fat_bread() (fat/buffer.c)?

No, I had not but now I have, thank you. Now that I have read it, I think
it is wrong, i.e. refers to the situation as it existed many years ago.

> Note that fat uses a logical sector size of 512 bytes, regardless of the
> hardware sector size.

Hmmm, I thought that this was the case in the old days but nowadays, if
you use windows98 to format the disk it stores the "logcal sector size" in
the first 512-bytes sector containg all the header information.

Btw, UnixWare7 deals with this correctly (i.e. uses the correct sector
size and not the 512-bytes-all-the-time). I was just curious if this was
the case with Linux and suspected yesterday that it's not. You seem to
confirm that.

Regards,
------
Tigran A. Aivazian | http://www.sco.com
Escalations Research Group | tel: +44-(0)1923-813796
Santa Cruz Operation Ltd | http://www.ocston.org/~tigran

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