Intermittent directory lossage, loopback, 2.1.72

Keith Owens (
Tue, 16 Dec 1997 21:57:45 +1100

Copying and comparing CD's.

dd if=/dev/cdrom of=/raw/xyz
Replace original with blank CD, WORM.
cdrecord speed=2 dev=0,3,0 /raw/xyz
mount /dev/cdrom /cdrom iso9660 -o ro
mount /raw/xyz -r -t iso9660 -o loop /mnt
diff -ur /cdrom /mnt 2>&1 | less

That last step should result in zero differences and has done so on
previous kernels on this hardware. However ...

One run got intermittent loss of files from the loopback image, the
files were on the new CD but did not "appear" in the loopback mount.
It was intermittent because ls -l /mnt/... initially did not show them,
a few minutes later the same command showed the "missing" files.

One file showed up as different on the two copies, missing lines on the
CD version. An explicit compare of the files showed they were really

Reissue the diff -ur command without umount or mount, no errors the
second time. Has something corrupted the disk cache?

2.1.72, Dual P166, 64Mb parity RAM, ncr53c875 SCSI, NE2000 clone.
AFAIK, everything is up to date except for mount, 2.6g instead of 2.6h,
unlikely to be the cause.