Hello All,
I have the following problem:
OS: FreeBSD 4.11-RELEASE.
DVD RW: acd0: DVD-R <_NEC DVD_RW ND-3500AG> at ata1-master UDMA33
I use DVD R's primary for data backup. The backup data is archived and splitted
on files ~500Mb size,
which was written on DVD-R's. I have also store the MD5 sums of those files in
small checksum file.
The problem is: sometimes then i check content on DVD the checksum is differs.
Where is no read errors on console,
and several attempts to calculate checksum return different results.
bash-2.05b# grep 00001 /cdrom/md5.sums
acc8b491f03bfa01e341808773a6f94f depot.147.tar.00001
bash-2.05b# md5 /cdrom/depot.147.tar.00001
MD5 (/cdrom/depot.147.tar.00001) = d821bd902c4b0e9c12510f302c10ee71
# File seems cached in RAM
bash-2.05b# md5 /cdrom/depot.147.tar.00001
MD5 (/cdrom/depot.147.tar.00001) = d821bd902c4b0e9c12510f302c10ee71
bash-2.05b# umount /cdrom
# After unmounting and mounting again - different (correct) checksum.
bash-2.05b# !mou
mount /cdrom
bash-2.05b# md5 /cdrom/depot.147.tar.00001
MD5 (/cdrom/depot.147.tar.00001) = acc8b491f03bfa01e341808773a6f94f
# Now the checksum is OK.
It seems for me that sometimes device correct soft read errors on media, and
sometimes - does not.
Does anybody have the same expirience (i.e. checksum differs without read
errors) ?
Best Regards,
Alexander Derevyanko
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