30 Mar
2000
30 Mar
'00
8:03 a.m.
OK, I've got a wierd question now. What is the lifespan of Magnetic Media?
In this case, I'm concerned about 4mm DAT, but since I'm more familiar with
8mm it as an example.
Let's say I've got a stack of 8mm tapes with data on them. They're
supposed to be good for archival purposes, when stored in the proper
conditions for 2 years.
Now let's say I've got a brand new box of 8mm tapes that have been sitting
around still sealed for 8 years. Again, they've been stored in the proper
conditions more or less. So are they still good? Is the 2 year number for
their ability to hold data, or the actual physical lifespan. Anyone have
any ideas?
The real reason for the question is finding some 4mm tapes that are still
sealed, and I'd estimate about 8 years old.
Zane
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30 Mar
30 Mar
8:26 a.m.
"Zane H. Healy" <healyzh(a)aracnet.com> wrote:
Now let's say I've got a brand new box of 8mm tapes that have been sitting
around still sealed for 8 years. Again, they've been stored in the proper
conditions more or less. So are they still good? Is the 2 year number for
their ability to hold data, or the actual physical lifespan. Anyone have
any ideas?
Hi
I think the 2 year is for reasonable useage.
New tapes should last for 30 to 40 years at least
with good storage. Tapes with data may not fare as well.
One of the biggest problem with old tapes is print
through. This is particularly true of the thinner
tapes. This is where some of the signal form
one layer in the spool shows up on another layer.
I've seen this on old audio tapes.
I've seen troubles with old floppies lately also.
What is the problem is the glue they use to hold
the inner surface pads onto the disk folder. It
bleeds through to the floppies over time and gets on
the disk. It then gets onto the heads as well ( sticky
stuff ). I resently recovered some data from some
disk that suffered from this and I had to clean the
heads between each disk. You could see that it did
some damage to the disk as well but I was able to
get data off with multiple tries.
Use short length tapes for long term storage and
you should get more years than you'll live.
Always make backups of backups and store in a
different location.
Dwight
9:25 a.m.
I think the 2 year is for reasonable useage.
Actually the 2 year number is from a government study that I don't believe
is still online :^( It was refering to writing the data to tape and then
sticking the tape in a vault. In other words an archive tape. They found
8mm was good for 2 years, while DLT and 9-Track tapes were good for 10
years.
New tapes should last for 30 to 40 years at least
with good storage. Tapes with data may not fare as well.
Hmmm, somehow I've got my doubts on them being good for that long, though
I've seen downright ancient 9-Track tapes used when I was working at a
Mainframe site.
My general suspicion is that they're good, and that the 2 year figure is for
the data on the tape, and that if one was to write over the tape again, that
it would probably be good for another two years.
Use short length tapes for long term storage and
you should get more years than you'll live.
Always make backups of backups and store in a
different location.
Dwight
Actually I've used CD-R for archives for the last 2-3 years. Though even
they should be refreshed probably every 5-10 years.
I'm just looking at finally getting my act together and setting up automated
backups on my Home OpenVMS cluster, and am looking to cut corners and save
some money by using this stash of tapes I just uncovered. Should be enough
tapes there to set up a small pool. Besides once I've got a good copy of
the data I'm going to shadow the drives :^) That's the other thing I should
have had going, but haven't gotten around to. You can never have your data
*to* safe :^)
Zane
10:11 a.m.
healyzh(a)aracnet.com wrote:
Actually I've used CD-R for archives for the last 2-3 years. Though even
they should be refreshed probably every 5-10 years.
Hi
It sounds like it might be a good idea to backup on
both medias. I don't know if there is enough information
of the kinds of problems CD-R's might have to really say
how safe they are. Some of the darnest things can come
back and bite you, like the bottle of cleaning solution
that the janitor uses.
Take Care
Dwight
9:02 a.m.
At 02:03 PM 3/30/00 -0800, Zane H. Healy wrote:
Is the 2 year number for
their ability to hold data, or the actual physical lifespan. Anyone have
any ideas?
Tapes seem to fail in a variety of ways. I'm not an expert but these are my
personal experiences and my working theorys, buyer beware!
1) They fail to stay magnetized.
I'm guessing due to heat changing the magnetic properties of the tape.
2) The oxide flakes off.
It seems the adhesive between the mylar and the oxide "dries out" or some
such and it just peels off. Usually leaves behind a clear spot.
3) They stretch.
Mostly this seemed to be a problem in an old Kennedy drive I used that
really sucked (vacuum that is!) and I don't think it did as good a job as
it could with the tape tension control.
4) They evaporate.
Now I've never ever seen a partially evaporated tape, however I have on
more than one occasion been absolutely positive I put some tapes in a box
in the closet, only to come back some time later and to have them
completely gone. Then again it could just be a "senior moment" :-)
--Chuck
9:49 a.m.
Tapes seem to fail in a variety of ways. I'm not
an expert but these are my
personal experiences and my working theorys, buyer beware!
1) They fail to stay magnetized.
I'm guessing due to heat changing the magnetic properties of the tape.
Now are you talking the physical properties of the tape, or the 'bits' of
data on the tape?
2) The oxide flakes off.
It seems the adhesive between the mylar and the oxide "dries out" or some
such and it just peels off. Usually leaves behind a clear spot.
This was one of my chief concerns. Any idea how long a 4mm takes?
4) They evaporate.
Now I've never ever seen a partially evaporated tape, however I have on
more than one occasion been absolutely positive I put some tapes in a box
in the closet, only to come back some time later and to have them
completely gone. Then again it could just be a "senior moment" :-)
I've seen this problem. What's worse is when it's a locked safe they
disappear from!
Zane
9:28 a.m.
Hi,
Let's say I've got a stack of 8mm tapes with
data on them.
They're supposed to be good for archival purposes, when
stored in the proper conditions for 2 years.
Are you sure about that? Two years sounds a bit short.
The real reason for the question is finding some 4mm
tapes
that are still sealed, and I'd estimate about 8 years old.
If it helps, I've been using DAT for music since 1993. I've got tapes I
recorded then which are fine now, the only problems I've ever encountered
are the occasional dropouts due to tape ware.
TTFN - Pete.
--
Hardware & Software Engineer. Sound Engineer.
Collector of Arcade Machines, Games Consoles & Obsolete Computers (esp DEC)
peter.pachla(a)wintermute.org.uk | www.wintermute.org.uk
--
1:39 p.m.
Let's say
I've got a stack of 8mm tapes with data on them.
They're supposed to be good for archival purposes, when
stored in the proper conditions for 2 years.
Are you sure about that? Two years sounds a bit short. If it helps, I've been using DAT for music since
1993. I've got tapes I
recorded then which are fine now, the only problems I've ever encountered
are the occasional dropouts due to tape ware.
Actually this does help, since my main concerns were physical deteriation
since, while these tapes are from about '92, they've never been used.
Zane
5:56 p.m.
OK, I've got a wierd question now. What is the
lifespan of Magnetic Media?
In this case, I'm concerned about 4mm DAT, but since I'm more familiar with
8mm it as an example.
The real reason for the question is finding some 4mm
tapes that are still
sealed, and I'd estimate about 8 years old.
Archival life is one of those statistical things. It has to take into
account sun spots, Roger rat taking a nibble, and the general river rising
sort of problems. My point being, a significant amount of failure will be
due to some sort of 'accident'. The only audio cassettes I have ever lost
were eaten by mean tape drives, and I have a number of 25 year old
cassettes I listen to still. OTOH I was mortified to hear that perhaps some
of my recordings on reel to reel Ampex 456 tape that I spent a fortune on
may now be starting to fail after the same time period.
Prudence suggests important data needs to be stored on several different
media types and in several different locations.
8798
days inactive
8799
days old
8 comments
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participants (5)
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cmcmanis＠mcmanis.com -
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healyzh＠aracnet.com -
mikeford＠socal.rr.com -
peter.pachla＠wintermute.org.uk