On Mon, Mar 29, 2010 at 12:13, Ben Scott <[email protected]> wrote: > On Mon, Mar 29, 2010 at 11:54 AM, Kurt Buff <[email protected]> wrote: >> http://en.wikipedia.org/wiki/Linear_Tape-Open#Tape_durability >> >> Seems pretty durable to me - 4 years, if entire tape written once per >> week. That seems unlikely. > > Beware. Understand what specifications are actually saying. That > particular scenario is not a directly applicable characteristic. > Nobody accesses (reads or writes) every block on a tape once and only > once before accessing it again. > > When I researched this, any given spot on the tape was rated at X > number of passes, individually. If one spot on the tape is passed > more often (for whatever reason), that still counts towards wear > limits. When you start getting errors on the tape, you retire it (at > least, I hope you do), so it doesn't matter if 99% of the tape is good > if 1% is degraded. In particular, the beginning of the tape tends to > get read/written a lot more often, because that's where the volume > header is. > > The table given in that Wikipedia article cites a link that 404's, > so I can't even begin to determine what the manufacturer might have > been talking about. > > We sure as hell don't get four years out of our once-per-week LTO2 > tapes before they start generating unrecoverable data errors. > > -- Ben
Oh, yes. If you read/write to the first foot of tape,.it counts. But, with our TSM system (with dual LTO3 drives in a 30 cartridge robot), this was never an issue. Never had to discard any tapes Now that we've switched to Ultrabac and a robot with a single LTO4 drive and 16 cartridges, we may have to pay a bit more attention to it. I suspect that doing D2D2T will help, though. We've got 3tb of disk on the backup machine, and we're backing up roughly 2.5tb of data in our fulls. Kurt ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~
