Subject: Re: Reading DLT does not stream?
To: Johnny Billquist <bqt@Update.UU.SE>
From: Jukka Marin <>
List: netbsd-users
Date: 09/01/2004 11:25:40
On Wed, Sep 01, 2004 at 10:20:07AM +0200, Johnny Billquist wrote:
> >It doesn't matter whether I do "gtar tvf" or "gtar xvf", so it's not
> >disk speed causing the rewind.
> Uh. Doing a "gtar tvf" will mean you're limiting yourself by the speed of 
> the terminal, which in many cases aren't all that quick, while "gtar xvf" 
> means you're limiting yourself by the disk.

Well, the files are rather large (50...500 MB each), so the terminal
speed really isn't a problem here :-)  Neither is disk speed (with
softdeps and a fast disk - the DLT runs at <3MB/s).

> Try something like "dd if=/dev/rst1 of=/dev/null bs=10240" and see if it 
> streams.
> That will make sure you're not limiting yourself by another device.

It does not stream.  Reads some data, rewinds, reads more, rewinds.. sigh.

> Apart from that, I'd expect there to be stops sometime when restoring from 
> a tape. Creating and populating files don't happen instantaneous, and 
> occasionally, the tape will have to wait a bit. Atleast that's what I 
> would expect.

Yep, especially with small files, but I'm archiving tarballs which are

Thanks for the quick reply.