Date: Mon, 2 Mar 2015 10:39:15 -0700 From: "Kenneth D. Merry" <ken@FreeBSD.ORG> To: Dan Langille <dan@langille.org> Cc: current@freebsd.org, scsi@freebsd.org Subject: Re: sa(4) driver changes available for test Message-ID: <20150302173914.GC87055@mithlond.kdm.org> In-Reply-To: <8EFB1A84-96E6-4F63-A6D0-A87432C02B72@langille.org> References: <20150214003232.GA63990@mithlond.kdm.org> <8EFB1A84-96E6-4F63-A6D0-A87432C02B72@langille.org>
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On Mon, Mar 02, 2015 at 11:45:59 -0500, Dan Langille wrote: > > > On Feb 13, 2015, at 7:32 PM, Kenneth D. Merry <ken@freebsd.org> wrote: > > > > > > I have a fairly large set of changes to the sa(4) driver and mt(1) driver > > that I'm planning to commit in the near future. > > > > A description of the changes is here and below in this message. > > > > If you have tape hardware and the inclination, I'd appreciate testing and > > feedback. > > This came to me today via the Bacula mailing lists. > > http://marc.info/?l=bacula-users&m=142531236722693&w=2 > > > As far as I can tell ltfs support on linux sits on top of the standard mt-st stuff \ > > as a userspace (fuse) filesystem > > I'd hope it's much the same with BSD. Removing the standard interface would be \ > > counterproductive overall > > Can you answer that and I'll relay please? Sure. In short, the current interface will stay in place. I have added additional ioctls that provide more features and information, but I don't see any issue with leaving the current ioctls in place. The MTIOCGET ioctl even gets an improvement in behavior when the tape drive supports long position information -- it will report the file number after a 'mt eod'. IBM's LTFS sits on top of their own Linux tape driver, and operates with a combination of tape driver ioctls (e.g. the standard MTIOTCOP ioctls) and SCSI passthrough. When I ported it to FreeBSD, I ran into several areas where we needed more information out of the tape driver. So that was the primary motivation behind adding the additional features. (Other features I implemented using SCSI passthrough.) He is correct that it runs with FUSE, although it can be linked into an application as a library as well. Ken -- Kenneth Merry ken@FreeBSD.ORG
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