Date: Sun, 06 Dec 2009 19:33:15 +0200 From: Alexander Motin <mav@FreeBSD.org> To: Alexander Best <alexbestms@wwu.de> Cc: freebsd-current@freebsd.org Subject: Re: Testing CAM wrapper for ata(4) controller drivers Message-ID: <4B1BEADB.5090803@FreeBSD.org> In-Reply-To: <permail-20091206154611f7e55a9d000070bb-a_best01@message-id.uni-muenster.de> References: <permail-20091206154611f7e55a9d000070bb-a_best01@message-id.uni-muenster.de>
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Alexander Best wrote: > i've stumbled over a problem with ATA_CAM. when i accessing my dvd-drive i'm > not able to access any other cam members (ada* e.g.). > > when i issue the following command: > > `cdrecord dev=2,1,0 blank=all' > > binaries such as ls, top or vmstat simply stall until cdrecord finishes. > > this is the output of `camcontrol devlist -v': > > scbus2 on ata2 bus 0: > <HDS722516VLAT80 V34OA63A> at scbus2 target 0 lun 0 (ada0,pass0) > <HL-DT-ST DVDRAM GSA-H10N JL12> at scbus2 target 1 lun 0 (pass1,cd0) > <> at scbus2 target -1 lun -1 () It was always bad idea to put CD and disk, which need to be used simultaneously, to the same PATA channel. PATA channel can execute only one command at a time, without using special technique, named overlap (part of TCQ), which is usually not supported by devices. When your blank command occupied CD, disk became inaccessible, until it complete. -- Alexander Motin
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