In comp.sys.ibm.pc.hardware.storage Dorothy Bradbury wrote:
MOD/DVD-RAM (similar technology) is very good for smaller backups
with high reliability requirements. Also for long-term storage.

Indeed - I use MO for just that reason, however now also use DVD-RAM:
o MO media QC has blips - a few too many
---- Sony 540MB 3.5" -- block errors on new disks
---- Fujitsu own 3.5" -- block error on *same place* on every disk - factory format
error
o DVD-RAM has been ok - and is higher capacity
---- £ 10 will get a two-sided 9.4GB disk
---- LG-4082B will write to them once removed from the caddy

Since I use DVD-RAM once-only for archive the removal from the caddy
is minor. If bothered use cotton gloves - whatever - it's 15x MO
capacity for the same price.

Well, not quite. The last time I bought 3.5" 640MB MOs, I paid 5 Euro
for each. The cheapest DVD-RAM I find is the same price for 4.7GB.
That is a factor of 7. Still signifficant if you do large backups.

MO is best for the most critical backups
o It was designed for data reliability from the ground up like DLT
o It is not a converted audio standard like helical scan DAT, or DVD

I agree. In 7 years regular MO usage I have still to see my first
unrecoverable read error. (I had to clean cartridtges two times,
but that resolved the problems with them completely.)

However, the "real" MO systems are based around the 5.25" form-factor:
o New blue-laser ones offer a migration path to very high data capacities
o The 5.25" form factor is relatively well proven in medical/mil/industrial

Actually many hostpitals in Europe use 3.5" MOD for computer images.
They have to keep the info for 20years by law, e.g. in Germany
or Switzerland and a few of these 640MODs are enough for a day.
I would say 3.5" MOD is professional today. 5.25" MOD seems to
have stalled development some time ago.

For the most part, DVD-RAM offers a good half-way house:
o Reliability is good - it is Phase-Change unlike DVD+/-R &
has better error correction
o Drives are cheap - so having 2 different branded drives
isn't impossible (or suppliers :-)
o Disks are cheap - 9.4GB can be had for just £6.99, sealed,
a bit more elsewhere

However there is the cartridge issue. Drop a DVD-RAM and it may
be gone. A MOD does not care. Also remember that MOD has 30 Million
certified overwrites while DVD-RAM without cartridge only has 10.000.
If you only do backups, that does not matter much. I also use my MODs
in "HDD mode", i.e. move around files, do small changes, etc..

MO is ~£200 drive & ~£10 media for 1.3GB v ~£60 drive & ~7 media for 9.4GB.
Critical stuff is best on MO, but with those media errors I think it's
forget about decades:
o Yes, backup media can last a long time - DVD-RAM probably, MO most probably
o However, it is perhaps more economic to keep changing technology every
few yrs
---- because technology will offer more capacity, perhaps more
reliability for less cost
---- that is particularly so with media cost as archives grow - eg,
DVD-RAM v MO

Depends. I have still about the same needs for high-reliability backups.
After I nearly lost some important stuff 7 years ago, I got a 640MB
MO drive. I still get my system and home backups on just two of these
disks and I still have all the original disks and the original drive
in use without problems. The last time I bought disks is 3 years ago,
the ~30 GB ultra-reliable storage I have is more than enough.

For the less critical stuff I keep copies on other computers.

MOD is fit to keep you Master's thesis, family photos, tax data you
need to store for decades (in some countries), scans of your degree,
in short all the things you absolutely do not want to loose. Also most
data recovery companies will convert MOD to some other format for you
for a modest fee and that type of offer should be around really long.
So even if you do not have a drive anymore in 30 years, that data
should still be accessible.

If your storage needs grow fast (my orgiginal complete systems backup
fit on just one 640MB MOD), then MOD is not the right solution
today. (It was by far the cheapest 7 years ago. And it is still
around. That should tell you something.)

Agreed - many people backup to DVD-RAM or HDs "incorrectly"
o They simply drag-n-drop files - directory is there, so it must be ok
o Better to use a proper backup tool - that actually does a proper compare
---- altho even XCOPY can be forced to do a verification as I recall
---- on DVD-RAM that might be an exercise in s-l-o-w-n-e-s-s however

Actually you should script this stuff. I am still surprised that MS
does not deliver a proper and easy to use backup tool with thir OS.
It is not that difficult. I use unix tar, perhaps one of the oldest
UNIX tools with good success.

If HDs are used, I prefer a "micro-PC" converted to NAS - with a few
Yes, that is what I use at home for the less critical stuff.
A Mini-ITX box with a 120GB HDD is just fine for this.

scripts to check the data integrity progressively to another
identical machine working in parallel. That need not be particularly
expensive - Mini-ITX snails don't cost much, recycle some of the
older 1U PSUs, make/re-use a case, whatever. Match solution to data
criticality.

.... and to data amounth and actuallity. Only then will you get
something satisfactory.

Arno
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