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 I'm just getting a chance to re-investigate the possibility of determining my Sony AIT tape drive's wound position. It would be extremely convenient to read via the command line in my backup scripts, and for remote administration. See replies listed below: On Wednesday 30 October 2002 16:26, Dan Nelson wrote: > In the last episode (Oct 30), Matthias 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. > 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 target 5 lun 0 (pass0,sa0) <SONY TSL-A300C L107> at scbus1 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 than or fewer than 2 pages. How do I use this output? What is it? I'm not familiar with low level SCSI, or FreeBSD Cam. But if you can give me some on-line references, I'd 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, 'chio' works great. I can now determine which tape is loaded, and swap tapes from the command 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 rdspos and rdhpos outputs, but since my drive uses variable block size, I'm afraid it's hopeless.... It gives me a number, but I can't make any sense of it. I've tried multiplying by 1024, 512, 2048, 256, 128, etc... but nothing comes up with a number close to what the drive's LCD "wound" indicator displays. Thanks. I hope you can point me in the right direction for 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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