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Date:      Thu, 30 Jan 2003 19:07:58 -0500 (EST)
From:      Mitch Collinsworth <mitch@ccmr.cornell.edu>
To:        "Kenneth D. Merry" <ken@kdm.org>
Cc:        joe mcguckin <joe@via.net>, hardware@FreeBSD.ORG
Subject:   Re: DLT tape not streaming
Message-ID:  <Pine.LNX.4.51.0301301905210.13748@ori.ccmr.cornell.edu>
In-Reply-To: <20030130160348.A67127@panzer.kdm.org>
References:  <BA5EEC45.1F66F%joe@via.net> <20030130160348.A67127@panzer.kdm.org>

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On Thu, 30 Jan 2003, Kenneth D. Merry wrote:

> On Thu, Jan 30, 2003 at 14:50:45 -0800, joe mcguckin wrote:
> > Our DLT-7000 tape drive does not stream continuously - there's quite a bit
> > of shuttling back and forth.
> >
> > Are there any SCSI parameters I can tweak to improve it's performance?
>
> What are you using to do backups?
>
> dump(8) is notoriously inefficient; I would recommend using Matt Dillon's
> caching tweaks to dump (use the -C option).  They'll probably speed
> things up somewhat.
>
> Another option is dumping the whole thing to a file, and then use
> dd to send that dump image to the tape drive.  I use that technique on a
> number of machines.

DLT7000 will do this if you can't feed it data fast enough.  You
don't need to tweak scsi you need to send the data faster.  As
Ken pointed out there are various ways to do this, depending on
what you're trying to do.  I'd suggest using amanda with a holding
disk.

-Mitch

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