Re: DDS4 - hardware compression not working

"Folkert Rienstra" <see_reply-to@xxxxxxxx> wrote in message
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"Larry Hodges" <2larry2@xxxxxxxxxxxxxxxxxxxxxx> wrote in message
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"Michael Baeuerle" <michael.baeuerle@xxxxxxxx> wrote in message
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Larry Hodges wrote:

I have a DDS-4 Seagate 40 (also called an Archive Python), model
STD62401LW-S. It's 20gb native, 40 gb compressed. However,
apparently
compression isn't working. I conclude that because at 20gb into the
backup,
I'm prompted for a 2nd tape. I'm using NTBackup, the built-in backup
app
with x64. I've tried it with and without software compression
enabled.

What data are you writing on the tape? Some types of data like audio or
video cannot be compressed at all or at very bad ratios by the lossless
compression algorithm used in DDS drives.


Micha

Maybe half of the data are JPGs. The rest, website backups, database
apps,
installation packages, deployment packages, programming projects, Word
and
Excel docs, etc.

I've run a test application that says compression is working properly.
However, I'll go to do a backup. The pre-compressed calculations will
say 26gb.

In my way of thinking,

Which is?

that should fit on a 40gb compressed tape.

And why is that, in the absence of a 'compressed calculation'?
What are the prerequisites for getting 40GB on such tape?
I'll bet it is maximum compressible data and full uninterrupted streaming.
So how do you insure the streaming part?

You may have a point Folkert. I've watched the data stream, and it starts
around 320mb/m, but slows through the backup to around 160mb/m. I have a
dual channel card...39320A. (It's in a standard PCI slot, not PCI-X.) Raid
is on B. On A, the tape, a U320 HDD, a U160 HDD and an old Ultra2 Wide HDD.

This may be the entire issue. The SCSI channel is saturated, data stream
slows and hardware compression turns off?

It doesn't. I tried StompSoft's BackupMyPC tonight with the same
results.

That's a nice application btw. The only non-enterprise level backup app
that backs up open files. Only about $40 too. Also works great on x64.
Roxio doesn't.

Any other ideas?

Make an image backup?

What's an image backup?

And, thanks for the input Folkert. I appreciate the input.

-Larry


.

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