Date: Wed, 7 Jul 1999 11:46:59 +0900 (JST) From: ohashi@mickey.ai.kyutech.ac.jp (Takeshi OHASHI) To: ken@plutotech.com Cc: garbanzo@hooked.net, dmiller@search.sparks.net, freebsd-hackers@FreeBSD.ORG, akiyama@kme.mei.co.jp Subject: Re: DVD-ram Message-ID: <199907070246.LAA01724@atohasi.mickey.ai.kyutech.ac.jp>
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ken>>Alex Zepeda wrote... ken>>> On Tue, 6 Jul 1999, Kenneth D. Merry wrote: ken>>> ken>>> > IMO, DVD drives are probably best handled through the CD driver, and ken>>> > Optical drives are probably best handled through the DA driver. The ken>>> > CD driver doesn't currently handle writes, but it's a one-line fix to ken>>> > change that. ken>>> ken>>> >From what I can tell, some of the DVD-RAM drives are actually treated as ken>>> disks (would use the da driver). For example, check out ken>>> http://mpeg.openprojects.net/panasonic.html to see the Linux "driver" for ken>>> the Panasonic LF-D100. The comments outnumber the code. ken>> ken>>Well, that makes sense from one perspective, and doesn't make sense from ken>>another perspective. ken>> ken>>Sure, DVD drives look like a disk from the standpoint that you can use ken>>standard read *and* write calls on them. ken>> ken>>But in most other ways, they're like CDROM drives. You can play audio CDs ken>>in them, mount regular data CDs in them, etc. With a disk driver, you ken>>don't have any of the special ioctl set to deal with CD-type drives and ken>>media. ken>> ken>>In fact, you probably wouldn't be able to mount disk with an ISO 9660 ken>>filesystem using the da driver, since it doesn't support the TOC ioctls ken>>that the cd9660 filesystem code uses. (because DA devices don't support ken>>those SCSI commands) ken>> ken>>The best of both worlds for accessing a DVD-RAM drive would be to just add ken>>write support to the CD driver. The CAM CD driver already has write ken>>support, but it isn't currently enabled. ken>> ken>>The attached one-line patch enables write support, and should make things ken>>just work. If anyone has a DVD-RAM drive and cares to test it, I'd be very ken>>interested to hear how things work. ken>> ken>>Ken ken>>-- ken>>Kenneth Merry ken>>ken@plutotech.com How do you think about some MO(Magneto Otpical disk) and PD drives? 3.5" 650MB and 1.3GB MO drives should handle 512KB/sector(128MB, 230MB, 540MB) and 2048KB/sector media(640MB, 1.3GB). Some PD drives use 2 LUNs. One of them is used for CD drive mode and another is for PD drive. How do you treat write protection? DVD-RAM type II media can be remove from the cartridge and be read as like as DVD-ROM media by some latest DVD-ROM drives, for example Panasonic's. But the striped DVD-RAM media is treat ad read only media by DVD-RAM drive. In addition, there are many bugy MO drives, ex. cash probelem, and media, ex. formated media for Windows. They cause to need some extra error handling. We were very happy to use DVD-RAM/MO/PD drives on FreeBSD-2.2.X, because pre-CAM SCSI system had the od-driver. We could not use these devices on FreeBSD-3.X without the new od-driver. Thank you very much, Mr. Akiyama. -- Takeshi OHASHI ohashi@mickey.ai.kyutech.ac.jp ohashi@jp.FreeBSD.ORG To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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