Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!elroy.jpl.nasa.gov!decwrl!fernwood!portal!cup.portal.com!DrBob From: DrBob@cup.portal.com (Robert A Rethemeyer) Newsgroups: comp.sys.amiga.hardware Subject: Re: A3090 tape driver ??(Re: BTN 2.0 Tape handler) Message-ID: <41542@cup.portal.com> Date: 22 Apr 91 10:25:06 GMT References: <1991Apr13.014520.13657@sugar.hackercorp.com> <61897@masscomp.westford.ccur.com> <5692@media-lab.media.mit.edu.MEDIA.MIT.EDU> Organization: The Portal System (TM) Lines: 74 Masuru Sugai writes... > [Scott Denham posting deleted] > [Mark Thompson posting deleted] I believe these gentlemen's difficulties are different than yours, and different from each other's. I sent them email, but have not received any response. > I've been frustrated with my A3090 (C= 150MB QIC) I picked up yesterday. I thought it was called A3070. Is A3090 something new? > I gave up MWtape and went to BTN. BTN seems quite useful, especially its > tapemon tool is wonderful as it shows what's going on in tape drives. > But there are several glitches. > > - I could store and restore files only when I set tape buffer to 512B long. > Buuut, it's slow (say, 15KB/sec) and consumes most of tape for block gaps ! > Nearly 80% of tape has used to just save 30MB. Many (maybe most) tape drives can use ONLY one size of tape buffer, usually 512 bytes. BTN allows you to specify different sizes for those drives that can vary it, but *not all drives can do this*. What do your drive docs say? You can still get good tape performance by increasing the number of blocks parameter. Try NB-128, which will give you 64KB data transfers (for BS-512). Tape performance is dependent on the total number of bytes transferred, not the buffer size. If you can't increase BS, then increase NB. The drive usually has no practical restriction on blocks per read/write. > - With buffer size over 1024B or more, TAR seems to write all data on tape. > Archiving speed is around 90KB/sec when I set buffer size to 64KB, > acceptable performance, judging from A3090 transfer rate (112.5KB/sec). > This is an option for a write-only mode, though. I can read, say, first > megs, but as soon as I hit upon a large file (a few hudred kilobytes), > TAR quits with Tapemon's "SELECTION TIMEOUT ERROR" message. I am better > off than they are, as I am free from lockup and guru SO FAR. SCSI SELECT TIMEOUT ERROR is printed when scsi.device returns the error code for this bus error. I'm not familiar with exactly what condition causes this error. But maybe this... if the drive and the handler have different ideas about what the buffer size is, it may confuse the adapter. The error happening on the read but not the write would seem to point to this. Try going back to BS-512 and NB-128. > I know what BTN stands for, but it is a decent implementation of tape > driver on standard Amiga configuration. It would be a BTA with a little > bit more of error handling... Any idea ? When I started on it a year ago, that's all that was available- NOTHING. I figured whatever I came up with had to be better than that :-) As for better error handling- I presume you mean error reporting? All I can do is report in english the error codes returned by the tape drive and scsi.device. I know of no means to determine the problem in any finer detail (at least for generic drives and adapters). > BTW, does anybody have working experience of TAR to exchange data with UNIX ? > I have no idea what is the most appropriate block size, as A3090 has nothing > technical on its booklet. Is there any preferred block size for each UNIX ? I know a couple people who have exchanged Unix TAR tapes with BTN, no problem. I don't think TAR will let you vary its data blocks on the tape, so as long as the medium is compatible, the exchange should work (but I could be wrong). Just curious- what does TapeMon report for the drive manufacturer/model? > -- Masaru Sugai =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Bob Rethemeyer // "My Sneaker-Phone keeps kicking my DrBob@cup.portal.com -or- // Football-Phone off the hook." ..!sun!portal!cup.portal.com!DrBob // - Jay Leno