Date: Thu, 2 May 1996 20:01:19 +0200 (MET DST) From: Wilko Bulte <wilko@yedi.iaf.nl> To: FreeBSD-hackers@freebsd.org (FreeBSD hackers list) Subject: using DLT drive on FreeBSD Message-ID: <199605021801.UAA01622@yedi.iaf.nl>
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Hi there I 'found' myself a DEC TZ87 DLT drive destined for the scrapyard. This is a 10/20Gb device (the 20Gb is using the optimistic 2:1 compression). Quantum calls this a DLT2000. Apart from solving my backup needs for the foreseeable future :-) I also have a few questions: 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. 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.?) It is of course also possible that the HD & tape being on the same NCR810 are hurting the streaming operation. 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 --------------------------------------------------------------------------------
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