8mm data cartridges

[Patrick Finnegan]

On Tuesday 08 May 2007 12:44, Al Kossow wrote:
>  > I always figure there's a lot less to go wrong in a DLT cartridge
>  > than there is with a hard disk
>
> The flaw in this argument is the time it takes to make another copy,
> which needs to be done at some point to migrate to newer media.
>
> You will only know the DLT has failed when you try to read it again.
>
> If you care about the data, it should be kept in a form that is
> easily replicated and verified, and you should assume that any single
> copy of that data WILL become corrupted or unreadable over time.

I mostly agree here... but at some level of data storage, tape is much 
more economical to use than hard disk.

Up until this year (that is to say, through December 31 or so of last 
year ;) we have used DLT media for our archival storage system here at 
work, starting in about '96.  Keeping two copies of the data is really 
essential, but even with the 50+TB of content that we had in the system 
when we started migrating to our new one (from DLT-IV in a DLT7000 
drive to LTO2 tape), we had very little data ever lost, and I don't 
think any data that got lost could be credited to the tapes - mostly 
just due to bugs, power failures, etc with our HSM system.  

But again, we did have bad tapes on occasion (hint: avoid Imation tapes) 
but they were few enough in number that we never had a big enough 
problem to lose data on two tapes that had the same data.  Still it 
wasn't too bad, IMO, as some of our tapes had over 1000 tape-mounts, 
with no problems at all.

So, I guess my advice if you want to use DLT tape (or newer, LTO stuff 
which is starting to trickle down) is to make sure the tapes are in a 
good, climate controlled environment, make sure you have 2 copies of 
the data, make sure you clean and test the drives regularly, 
occasionally read the tapes to make sure your data is still there, so 
that you can regenerate a 2nd good copy before you have 2 bad copies.

Pat
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