When to replace storage media?

[mjnews]

I have been asked hundreds of time what the life span of DDS-4, SDLT,
DLT, 8mm, taravan, and other tape media is, as long as how long the
shelf life is. Most manufactures seem to agree that magnetic media can
last up to 30 years on the shelf, depending on the environmental
conditions. Some of them, such as Fujifilm, rate their DDS-4 tapes at
5,000 head passes. With such numbers, however, it is impossible to
calculate the exact MTBF on any magnetic media, as one never knows the
exact passes of the head the tape will undergo during a backup. Has
anyone seen any reports on the lifespan of storage media in general?

One person on the newsgroups, in 1998, said there was a DoD report on
media retentively, reliability, etc. The report was supposed to cover
magnetic media including tapes and hard drives. I am also interesting
in getting the same information for magnetic tapes, magnetic platters
(hard drives), and optical media (CD, DVD, ...). The same person said
the report rates the shelf life and/or life expectancy of hard drives
at 3 years. I also saw other reports on the Internet of a 3-year life
expectancy for hard drives. However, I personally have floppies that
are almost 14 years old that I can still read fine, let alone I have
seen computers dug out of the worse environments after sitting there
for years and the drives run fine.

So, does anyone really know when one should replace their storage
media, or do we just continue to use it until it fails; only praying
that it doesn't fail when we are doing a restore?!? Thanks for your
input.

Matt

 

[Arno Wagner]

I have been asked hundreds of time what the life span of DDS-4, SDLT,
DLT, 8mm, taravan, and other tape media is, as long as how long the
shelf life is. Most manufactures seem to agree that magnetic media can
last up to 30 years on the shelf, depending on the environmental
conditions. Some of them, such as Fujifilm, rate their DDS-4 tapes at
5,000 head passes. With such numbers, however, it is impossible to
calculate the exact MTBF on any magnetic media, as one never knows the
exact passes of the head the tape will undergo during a backup. Has
anyone seen any reports on the lifespan of storage media in general?

One person on the newsgroups, in 1998, said there was a DoD report on
media retentively, reliability, etc. The report was supposed to cover
magnetic media including tapes and hard drives. I am also interesting
in getting the same information for magnetic tapes, magnetic platters
(hard drives), and optical media (CD, DVD, ...). The same person said
the report rates the shelf life and/or life expectancy of hard drives
at 3 years. I also saw other reports on the Internet of a 3-year life
expectancy for hard drives. However, I personally have floppies that
are almost 14 years old that I can still read fine, let alone I have
seen computers dug out of the worse environments after sitting there
for years and the drives run fine.

So, does anyone really know when one should replace their storage
media, or do we just continue to use it until it fails; only praying
that it doesn't fail when we are doing a restore?!? Thanks for your
input.

Very difficult question and very dependent on the concrete media,
conditions and random chance. Personally I have made the experience
that 3.5" floppies have widely varying data lifetimes. There seems
to be a connection to the brand. I would not trust them for any kind
of long-term storage.

Then there is tapes. Depending on the amount of interleaving and ECC
done and on the sensitivity of the reading equipment they may
be suitable for short-term storage only (my experience with QIC-80)
or long-term storage for decades.

Fro CD-R I have had both disks that verified fine defect after 4 weeks
and still perfectly fine after several years.

HDDs in my experience fail when in use. I never had a disk that
sat on a shelf for some time fail immediately. However whetner
they keep 5 years or 50 years is very hard to tell.

Bottom line: There is no simple answer as the technology of digital
storage is still not really well understood or mature.

Arno

 

[mjnews]

Thanks for the reply Arno. I received some excellent information from
the folks at Fujifilm after I contacted their technical support via the
website. What it boiled down to was DAT, Taravan, and 8mm tapes should
be replaced about once every 1.5 years. DLT and LTO tapes will
typically last up to their 30 year shelf life, even being used, so
there is no need to replace them unless many errors are seen. Fujifilm
sent me some documents where they have calculated the lifespans by
knowing the number of passes each drive type makes over the tape
header, and then by knowing the number of passes each tape is rated
for.

Matt

 

[Arno Wagner]

Thanks for the reply Arno.

You re welcome.

I received some excellent information from
the folks at Fujifilm after I contacted their technical support via the
website. What it boiled down to was DAT, Taravan, and 8mm tapes should
be replaced about once every 1.5 years. DLT and LTO tapes will
typically last up to their 30 year shelf life, even being used, so
there is no need to replace them unless many errors are seen.

Yes, that seems very valid data. Also for DLT and LTO you are
likely to get reasonably priced data recovery for a long time,
since these media are in the professional category.

Fujifilm
sent me some documents where they have calculated the lifespans by
knowing the number of passes each drive type makes over the tape
header, and then by knowing the number of passes each tape is rated
for.

Yes. If used sparingly, DAT, etc. will be good for some more years
but not decades.

Arno