Date: Fri, 27 Jul 2012 01:51:24 +0300 From: Alexander Motin <mav@FreeBSD.org> To: Andriy Gapon <avg@FreeBSD.org> Cc: freebsd-scsi@FreeBSD.org, freebsd-geom@FreeBSD.org Subject: Re: [RFC] CAM/GEOM media change notification Message-ID: <5011C9EC.5080008@FreeBSD.org> In-Reply-To: <500E538E.1060908@FreeBSD.org> References: <500D54B9.1010800@FreeBSD.org> <500E538E.1060908@FreeBSD.org>
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On 24.07.2012 10:49, Andriy Gapon wrote: > on 23/07/2012 16:42 Alexander Motin said the following: >> Patch can be found here: >> http://people.freebsd.org/~mav/mediachange8.patch >> >> Any comments/objections/propositions? > > Alexander, > > would it make sense for scsi_cd to also use GET EVENT STATUS NOTIFICATION > command (4A) with Polled flag and Media bit set in Notification Class in > addition to TUR for devices that do not support asynchronous notification? > > I think that this should increase reliability of detecting CD media changes > between polls. Thanks for the hint. I've read about that command, but haven't found it useful. If media was quickly removed and reinserted and we missed it, then device will send us UNIT ATTENTION on first following request, which we will handle. If media was quickly inserted and removed and we missed it, then we just have nothing to do about it. It could be interesting to use GET EVENT STATUS NOTIFICATION in asynchronous mode to avoid polling, but it works only for queued commands, which are not supported by ATAPI devices. -- Alexander Motin
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