General discussion


Backup tape useable life and archiving

By Brenden ·
The other day one of my clients asked me how long they should keep using the same data tapes. My inital thoughts were until they start to have errors. But then it occured to me that you might want to stop using then well before then.

So my question is, how do you tell if a tape is degrading?

Does the age of the tape and the number of time it has been used degrade its ability to store the data?

What archive cycles do other members use or suggest using?


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Tape is poor choice for long term data storage

by stress junkie In reply to Backup tape useable life ...

I was in charge of backups, among other duties, at my
last job. The company had archive tapes stored off site
going back up to a decade. I can tell you that the tapes
that had been stored 5 years or more often could not
be read by the tape drives. When I realised this it
seemed to me that the requirement to store the data 7
or 10 years meant that we would have to recall tapes
after, say, 4 years and copy them to another tape. I
don't think that the old tapes were mechanically bad.
Rather I think that the magnetic signal had degraded.

However, it seems to me that the ONLY reasonable
solution today is to use DVD-R and DVD-RW disks. The
cost/capacity is about the same as tape but the drives
are much less expensive and the data can reasonably
be expected to retain its integrity for 30 years. You can
even reduce the cost of the long term archives by using
write once DVDs. Backup software like Veritas can use
the DVD format. And the DVDs are not going to be
erased by magnetic fields. I've seen many people put
magnetic tapes on top of or beside huge CRT monitors
and then wonder why they couldn't recover data from
those tapes. Duh.

So tape stinks. DVD-R and DVD-RW are great. Price is
comparable between the two media formats.

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Now to answer your question

by stress junkie In reply to Tape is poor choice for l ...

I realised that my resonse strayed a bit from your
question. I'll say this about tape life. I've used old DLT
tapes reliably for daily backups. These tapes would be
recycled about every three or four weeks. I almost
never had trouble recovering data from these tapes
although they were used frequently, not just for
recording the backups, but by also recovering data for
people that considered backups as near line storage.

I recommend using backup software that verifies data
by reading the tape as it writes the backups.

I suspect that the tapes' useful life was comparable to
the life of the tape drives. I know that's surprising and
counterintuitive because the tape has to contact the
drive heads to be used, but that's what I've seen. So I'll
say that the life of a DLT tape is probably greater than
5 years. I'd keep using a tape until I got errors creating
a backup. Don't forget to use a bulk tape eraser before
discarding old tapes.

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HP tape Drives

by pgm554 In reply to Now to answer your questi ...

HP drives write header info on the tapes and after so many uses ,will refuse to use the tape for archiving purposes.

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HP the only way to go

by dduncan4 In reply to HP tape Drives

HP has tape life down covered. I only use HP tapes and drives. My backup software can monitor the usage and tells me when it's time to get rid of this tape. It may be more expensive, but just wait till you need to restore that backup.

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Usable Tape Life

by msg2612 In reply to Now to answer your questi ...

At our office we still use DDS4 20/40. I have a 9 tape set in place -- one each for Monday thru Thursday, then five separate tapes for Fridays, so we can go back four weeks if necessary.

I use these sets for one year before pulling them and creating a new set. I found in the past that the DDS3 & DDS4 tapes I was using for a little over a year would become error prone.

A DVD loader would be great to have as a backup resource. Each backup solution has its drawbacks, though. I've been reading a lot lately about how easily CD/DVD is damaged, so...

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Of backups and archiving

by Phil Spiby In reply to Tape is poor choice for l ...

Although this is not answering the question asked, I thought it may be useful to add some insights on digital archiving based on Stress Junkies response.

If the customer was actually wanting long term data retention then your approach of using DVD media (because it has an expected integrity of 30 years) is not the whole answer. Which ever media (and even data format) you choose now will be obsolete in 30 years. Punched cards (in regular use 30 years ago) have a good data retention period, but how many people would consider trying to use a punched card reader now? The same will be true for DVD's in 30 years time.

To achieve long term data retention you need to accept the fact that media and data formats will change over the life of the archive.

An excelent standard in this area is "ISO 14721:2003 Reference Model for an Open Archival Information System (OAIS)". Goes into great detail discussing preservation planning and media migration strategies.

The Pharmecutical, Nuclear and Aerospace industries are addressing these issues now using OAIS, in the certain knowledge that if they don't then Digital Doomsday (when you cannot recover a piece of critical digital data) will not be far away.

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Tape should be abolished

by Warren Sever, MCP In reply to Tape is poor choice for l ...

Tape is ancient technology and, when compared to the alternatives, tape is clearly the worst choice.

I recommend and use hard drives. They're screaming fast and instantly accessible.

For archiving, DVDs are the answer.

I'll take this opportunity to go off topic a bit and take a shot at the entire electronics industry. Digital camcorders should have hard drives, not tapes. C'mon, people, wake up and give me the technology I want!

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How do you handle off-site storage?

by Ed_Gooding In reply to Tape should be abolished

>> I recommend and use hard drives. They're screaming fast and instantly accessible. <<

Do you use hard drive caddies and store the backup hard drives off-site. If you don't take your backups off-site, what is your disaster recovery procedure if the building housing your system(s) and backup drives burns down?

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Send it offsite

by Warren Sever, MCP In reply to How do you handle off-sit ...

If your site is a large campus, you could send it to another building to your backup server(s) there. This has enough value to even build a small backup "vault" onsite at a large campus. Then you have some disaster proofing built right in.

Smaller backups can be sent to an offsite server via the Internet if you have a big enough pipe.

Removable drives would be an option only for a small system. Much care would need to be taken to ensure the drives don't get damaged while transporting on/offsite.

"Think outside the box of tapes."

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DVD vs Tape

by razz2 In reply to Tape should be abolished

I will get into tape life shortly but first:


Light bulbs are ancient as well but we still see their
purpose in life. Note that I say purpose and not

For a very small business, CD-RW is fine but a large
network backup operator would spend his life doing a
full backup.

For a Small/medium size, DVD is fine but has serious
draw backs. While they have a long shelf life they are
prone to read/write errors like any optical device. This
may be a device issue or as simple as a scratch. using
DVD to archive data is great because they are burned
and then stored. Rarely handled.

Also for Small /Med: you have the option of DVD or an
inexpensive tape such as a 20/40 Travan. Not a great
tape but it works for a standard rotation of 9 or 18 tapes.
It solves the offsite issue too. And, it is easy to setup for
automated backup when no tech is employed by the
company. Drive and tape cost is within reach of a small
company. Less risk of damaged backup mediawith a
tape compared to DVD is a benifit.

For a server room with 5 or 6 servers, including
Exchange and an SQL server, then DVD is not an
option. Even if they held 9 GB. I doubt they would make
it through a few offsite transfers safely let alone a few
restores. EVERYONE has scratched a CD/DVD on
inserting it to the tray. For this a Tape Loader is the key
regardless of format. DLT etc.

Backups simply provide access to data in a condition
from the past. That is NOT a true Backup Plan for
disaster recovery. In the event of a building burning
down, the clients, billing, books etc. are still available
with offsite storage. Onsite storage I see so often put in
a standard fire safe. Useless too. Even paper will char,
for media you need a media safe.

OK, now the question...sorry about the wait. Most of the
comments here reference a 9 tape rotation. I too use
this as a minimum. With tapes averaging $35 to $45,
with a purchase of 10, that is a whole set for $350 to
$450. I change tapes yearly. Tapes will last 5 years in
my experience based on use, but the drive may stretch
them. heat may damage them. Shelf-life is only part of
it, and then only if they are handled correctly. For less
than $450 a year I can protect the whole company with
tape. I can have it automated and available offsite.
Compared to the cell phone bills now that is very little.
A cost of doing business.

Just an opinion, but this is a great discussion.

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