From owner-freebsd-hackers Mon Jan 2 11:53:14 1995 Return-Path: hackers-owner Received: (from root@localhost) by freefall.cdrom.com (8.6.9/8.6.6) id LAA01798 for hackers-outgoing; Mon, 2 Jan 1995 11:53:14 -0800 Received: from prosun.first.gmd.de (prosun.first.gmd.de [192.35.150.136]) by freefall.cdrom.com (8.6.9/8.6.6) with SMTP id LAA01791 for ; Mon, 2 Jan 1995 11:53:06 -0800 Received: from g386bsd.first.gmd.de by prosun.first.gmd.de (4.1/SMI-4.1) id AA06657; Mon, 2 Jan 95 20:51:33 +0100 Received: by g386bsd.first.gmd.de (UAA28360); Mon, 2 Jan 1995 20:53:46 +0059 From: Andreas Schulz Message-Id: <199501021954.UAA28360@g386bsd.first.gmd.de> Subject: Re: Emulex MD21 question To: terry@uivlsi.csl.uiuc.edu (Terry Lee) Date: Mon, 2 Jan 1995 20:53:46 +0059 (MET) Cc: hackers@freebsd.org In-Reply-To: <199501021634.AA05527@uivlsi.csl.uiuc.edu> from "Terry Lee" at Jan 2, 95 10:34:04 am X-Mailer: ELM [version 2.4 PL24] Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Length: 1441 Sender: hackers-owner@freebsd.org Precedence: bulk > By any chance is anyone here familiar with the Emulex MD21 ESDI->SCSI > bridge? I'm trying to use one with a 10MHz ESDI drive and a 15MHz ESDI drive. > It does work, but the transfer rate to the 15MHz drive is only about 650KB/s. > I measured the transfer rate by both dd and CORETEST (DOS benchmark). It is > as if the MD21 formats 15MHz drives with a 2:1 interleave. Is this > a limitation of the MD21? Thanks for your time. My "Emulex SCSI DISK CONTROLLER PROGRAMMING REFERENCE MANUAL" :-) "The interleave factor may be specified during a format operation (see the FORMAT UNIT command)." FORMAT UNIT Command Descriptor Block: Byte 0 4 1 Logical Unit Number | FmtDat | CmpLst | Defect List Format 2 Format Data Pattern 3 Interleave ( MSB ) 4 Interleave ( LSB ) 5 Vendor Unique | Reserved | Flag | Link An interleave value of 0 or 1 requests that the target use its default interleave ( 1:1 sequential ). What you may see is the overhead of the poor 8031 that decodes the SCSI commands, this thing was never fast :-). The whole Manual from EMULEX 3545 Harbour Boulevard Costa Mesa, California 92626 (714) 662-5600 TWX 910-595-2521 MD2352501 Rev A May, 1986 Look at the Date, i don't know if the address is valid anymore :-). ATS ( ats@first.gmd.de or ats@cs.tu-berlin.de ) Andreas Schulz GMD-FIRST 12489 Berlin-Adlershof Rudower Chaussee 5 Gebaeude 13.7 Tel: +49-30-6392-1856/+49-177-2134745 Germany/Europe