Re: [TCLUG:19863] 160mXL 8mm tapes = 24Gb?

[Brian <marshmallowmateys@email.com>]

I found the 8mm we use for AS/400 backups here.  It's a "helical scan"
whatever that means, but my 112m tape holds 2.5/5 GB, so if I math it out
(assuming it's linear) 160m should be somwhere around 3.5-4 GB uncompressed.
Is it possible that your drive will only take a 2/4 GB tape (either by
design or by "unfortunate incident")?

On Wed, 26 Jul 2000, Philip C Mendelsohn wrote:

> On Wed, 26 Jul 2000, Bob Tanner wrote:
>
> > Running Sparc Linux with a Exabyte 8mm Tape drive using 160mXL 8mm
tapes.
> >
> > I think I am going insane, but I thought 8mm did 12/24Gb. Yet, I am able
only
> > to get around 2Gb on the tape before it gives me a write error.
> >
> > Just wanted to make sure my capacity is right on the tapes before I look
else
> > where.
>
> Depends on the drive, but that's *way* higher than what I would expect.
>
> I have an Exabyte 8500C, which is rated for 5GB uncompressed, 10GB with
> the hardware compression.  (It's older, but it's a rock.)
>
> I don't recall if that was 160m tapes or not, but the difference for tape
> length is linear, so that doesn't explain it.
>
> 2GB is pretty shabby though.
>
> There are lots of annoying problems that could account for it -- bad
> tapes, dirty machines, yada, yada.  I have a fair amount of insight into
> the behavior of tapes and heads which I won't burden you with now :)
>
> I don't want to start a "I swear by brand X, but brand Y
> stinks" discussion, but I have some data on error rates, bad tapes
> received, and recoverability after time that suggests that the 3M /
> Imation 8mm tapes really do outperform a couple of other brands.
>
> *I'm not claiming they beat everyone else's tape.*
>
> Nutshell:  Your numbers probably aren't right, but your tape is *almost*
> certainly not doing what it's supposed to, IMHO.
>
> Cheers,
> Phil M
>
> --
> Lottery:    a tax on people who are bad at math
>
>
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