CASTalk.com

Svenne Krap · Guest

Hello.

Can someone come up with some expectations for lifetimes for different
tape solutions (Travan, DAT, DLT, Ultrium) for mission critical data.

That is in different situations:
- tape is written once, put in safe storage
- tape is written multiple times (some sort of rotation in the backup setup)

Both in terms of years and read/write ops before the tape is being
considered unreliable.

Official sources are preferred, but your (internal) rules of thumb will
be okay too.

Thanks in advance

Svenne

RPR · Guest

I have yet to see a single ((S)DLT or LTO) tape that was actually worn
out, except in lifetime tests at OEMs (after >1,000,000 passes.) Tapes
get dirty (often with wear related debris from the drive or
loader/library), or they get damaged by mishandling, improper storage
or bad drives. Those are the causes for media to fail. If you write a
tape and store it in a controlled environment, it will last longer than
you will be able to find drives to read it. The spec for both tape
types is 30 years. I have over 10 year old DLTtape III that I store in
an office drawer and they are just fine (not many load or RW cycles on
them though, maybe a couple 10), but I have relatively few drives left
that can still use them.
If you load a tape frequently, the life expectancy depends a lot on how
gentle your loader/library is. With good handling, the multiple-1,000
cycle specs are realistic, but many loaders or libraries handle the
media less than gentle and start creating debris within a few 100 load
cycles. You can often see wear marks from the robot or the magazines.
That polycarbonate dust ends up partly in the drive - on the head
(which you can clean) and on the media (which you can't clean, so the
dirt is snowplowed around by the head.)
Bottom line... tape handling and care is the most important factor for
long term reliabiliity. I have seen multiple cases where large data
centers with elaborate backup and archival schemes had tape transported
offsite into a vault, only to find that they could hardly read the data
when tapes were retrieved. It turned out that tape handling in the
vault or transport had damaged the media.
This applies to LTO and DLT media. Travan and DAT are in a different
class.

Ralf-Peter

	CASTalk.com Forum Index -> Storage System	All times are GMT
Page 1 of 1