Date: Mon, 2 Jan 1995 20:53:46 +0059 (MET) From: Andreas Schulz <ats@g386bsd.first.gmd.de> To: terry@uivlsi.csl.uiuc.edu (Terry Lee) Cc: hackers@freebsd.org Subject: Re: Emulex MD21 question Message-ID: <199501021954.UAA28360@g386bsd.first.gmd.de> In-Reply-To: <199501021634.AA05527@uivlsi.csl.uiuc.edu> from "Terry Lee" at Jan 2, 95 10:34:04 am
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> 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
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