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Subject: Re: using DLT drive on FreeBSD
To: wilko@yedi.iaf.nl (Wilko Bulte)
Date: Thu, 2 May 1996 13:31:49 -0700 (PDT)
From: "JULIAN Elischer" <julian@ref.tfs.com>
Cc: FreeBSD-hackers@FreeBSD.org
In-Reply-To: <199605021801.UAA01622@yedi.iaf.nl> from "Wilko Bulte" at May 2, 96 08:01:19 pm
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> 
> Hi there
> 
> First of all, the drive works just fine on my Asus P90/NCR810
> The main problem is that I cannot set the buffersize used by 'dump'
> to a high enough value to keep the tape streaming. These puppies need
> 1.3 - 2.5 Mbyte/second to keep streaming OK. The actual required rate is
> dependent on how good the data compresses. An experiment @ work with a
> Sun Sparc20 revealed a 1.9Mbyte/second transferrate while dumping the
> /usr Solaris filesystem. Side note: I had to put the drive on a seperate
> SCSIbus/adapter to make this work.
try piping your data throughgh 'team' (in the packages..)
it should up your throughput by allowing concurrent  file-system reads
and tape writes..

> 
> I think the 2.1R limit is 32kbytes. In the recent past there was a
> discussion about this on this list (in relation to DAT drives??). Didn't
> pay too much attention at the time because I did not have the drive then.
> Is there any way to increase this value (seem to remember there was not.?)
Actually it's 64Kbytes
> 
> It is of course also possible that the HD & tape being on the same NCR810
> are hurting the streaming operation.

no, that should be ok..

> 
> NB looks like I also have to hack a bit into 'mt' to allow the density/
> compression settings to work. WIll dig up the device spec to see what
> that has to say
> 
> Comments?
> 
> Wilko
> _     __________________________________________________________________________
>  |   / o / /  _   Wilko Bulte             email: wilko@yedi.iaf.nl
>  |/|/ / / /( (_)  Private FreeBSD site  - Arnhem - The Netherlands
> --------------------------------------------------------------------------------
>