Re: ufsdump (update)

From: DharmaFog (DharmaFog_at_VirtualMachines.COM)
Date: 05/29/04 

Date: Sat, 29 May 2004 07:53:58 -0700

slrn wrote:
> I'm still getting 9.929G on a 125m/4mm tape. Anyone getting
> anything close to 12G on an HP DAT24i 125m/4mm using ufsdump?
>
> I've tried: /dev/rmt/0 /dev/rmt/0cn /dev/rmt/0cbn, I've tried
> dumping zip/compress file with no hardware compression.
>
> Perhaps around 10G is normal for 125m/4mm tape? (capable of 12G)
>

The files are already compressed - so the maximum storage on
the tape is 12 Gbytes independent of hardware compresssion
(assuming the ratio of hardware compression to gzip compression
is roughly one.)

If you had one file which 12 Gbytes written to a perfect tape
with perfect heads you might get 12 Gbytes on the tape.

On the average, the maximum storage on the tape is roughly
around 70% of the hyped value. 9 Gbytes sounds about right.

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