I still back stuff up on optical media though maybe,
not for long.
I've had write failure in the past that I didn't catch until I needed
the content that, as it turned out, wasn't correctly burned to the disk!
So I now follow this ritual to immediately verify every burned file
after writing a disk.
# I always include a signature file in the root of a burned CD
# to easily verify that the CD was 100% correctly burned.
# Writing the hashes _above_ current directory so that hash file
# is not itself hashed.
find . -type f | sort | xargs md5sum > ../sigs.md5
# BTW the preceding won't work if any filenames contain spaces.
# You could make it work with...
#find . -type f | sort | while read F; do md5sum "${F}"; done > ../sigs.md5
# ...but much better to just insure no filename contains spaces!
# Move the hash file into the root to be burned.
mv ../sigs.md5 .
# Create a CD image
genisoimage -r -iso-level 4 -no-bak -v -V TAXHISTORY -o ../taxhist.iso .
# Using Schilly tools...
cdrecord-prodvd-2.01-pre-x86_64-unknown-linux-gnu -scanbus
# ...to figure out the SCSI device id of your CD writer, then...
cdrecord-prodvd-2.01-pre-x86_64-unknown-linux-gnu -sao -v -V dev=3,0,0 taxhist.iso
# Finally, eject and reload the CD, mount it...
eject
eject -t
pmount /dev/cdrom foo
cd /media/foo
# ...and verify all the MD5 hashes.
md5sum -c sigs.md5
cd -
pumount /media/foo
eject
Incidentally, the cdrskin utility in most repos is a good replacement
for Shilly's cdrecord.