Date: Tue, 26 Nov 2002 17:00:46 -0500 From: Matthias Trevarthan <trevarthan@wingnet.net> To: Dan Nelson <dnelson@allantgroup.com> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Sony AIT tape position question Message-ID: <200211261700.46508.trevarthan@wingnet.net> In-Reply-To: <20021030212603.GD42580@dan.emsphone.com> References: <200210301441.55643.trevarthan@wingnet.net> <20021030212603.GD42580@dan.emsphone.com>
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Well, it's been a while since this was posted, but=20 I'm just getting a chance to re-investigate the=20 possibility of determining my Sony AIT tape=20 drive's wound position. It would be extremely=20 convenient to read via the command line in my=20 backup scripts, and for remote administration. See replies listed below: On Wednesday 30 October 2002 16:26, Dan Nelson=20 wrote: > In the last episode (Oct 30), Matthias=20 Trevarthan said: > > I have a Sony AIT tape drive (one of the > > nifty 4 tape autoloaders): TSL-SA300C. It > > has a nice little display on the front that > > indicates the tape's "wound" status. When the > > tape is fully rewound, the bar graph is full. > > When the tape is fully recorded, or wound, > > the bar graph is empty. > > > > Is there any way that I can detect this > > programmatically? I would like my scripts to > > be intelligent enough that they can > > approximate the size required for a dump, and > > the size left on the tape. > > That's difficult. There definitely isn't any > standard SCSI command for pulling this info.=20 > Sony might provide it in a vendor-specific > modepage (readable with the "camcontrol > modepage" command; you can decode > vendor-specific pages by adding entries to > /usr/share/misc/scsi_modes). See if you can > find a technical manual for the AIT drive. Hmmm.... executed this: -------------- camcontrol devlist -------------- and got this: -------------- <SONY TSL-A300C L107> at scbus1=20 target 5 lun 0 (pass0,sa0) <SONY TSL-A300C L107> at scbus1=20 target 5 lun 1 (pass1,ch0) -------------- Then, I used that information to execute this: -------------- camcontrol modepage 1:5:0 -m 2 -------------- and got this for output: -------------- Buffer Full Ratio: 0 Buffer Empty Ratio: 0 Bus Inactivity Limit: 0 Disconnect Time Limit: 0 Connect Time Limit: 0 Maximum Burst Size: 1566 DTDC: 0 -------------- I couldn't get modepage output if I requested more=20 than or fewer than 2 pages. How do I use this output? What is it? I'm not=20 familiar with low level SCSI, or FreeBSD Cam. But=20 if you can give me some on-line references, I'd=20 be happy to educate myself. (story of my life!) > > > (I would also like to detect which tape I > > have loaded at any given point, but I suspect > > that is outside the bounds of standard SCSI > > communication. I'd probably need some > > proprietary code to do this...) > > If your autoloader has a barcode scanner, you > can read the labels with the "chio status" > command. Once I installed the 'ch' driver in the kernel,=20 'chio' works great. I can now determine which=20 tape is loaded, and swap tapes from the command=20 line. Cool stuff. Thanks! > > > When I use the 'mt' command with 'rdspos' I > > get a block number. Would this number be > > useful in determining how wound the tape is? > > If so, how would I go about interpreting this > > as a percentage or as a byte volume? > > rdspos gives you the logical scsi block number, > which doesn't mean much if your tape does > hardware compression, since a tape full of > zeros will have more logical blocks on it than > a tape full of zip files. rdhpos might work > better, if the tape drive actually ends up > writing fixed-size blocks to tape. I've tried to figure out a rhyme or reason to the=20 rdspos and rdhpos outputs, but since my drive=20 uses variable block size, I'm afraid it's=20 hopeless.... It gives me a number, but I can't=20 make any sense of it. I've tried multiplying by=20 1024, 512, 2048, 256, 128, etc... but nothing=20 comes up with a number close to what the drive's=20 LCD "wound" indicator displays. Thanks. I hope you can point me in the right direction for=20 the modepage thing. Matthias To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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