wtm@uhura.neoucom.EDU (Bill Mayhew) (10/18/90)
I've been trying to figure out a way to prevent shoe-shining of the tape (repeated short back-and-forth movement) on a 60 meg Sperry/CMS Wangtek tape drive on my Sys V 386 3.2.1 system. I did find /usr/local -name "*" -print | cpio -oc -C1024 > /dev/rmt/c0s0 The system has 8 megs of RAM, and there weren't many processes running, so cpio should have gotten the whole 1 meg buffer (I think??). It took about 1/2 an hour to back up about 5 megs of data from /usr/local. Yuck! Running the same hardware under the DOS partiton with the CMS QIC streaming software backed up up 30 megs in just under 6 minutes with the tape running continuously. The tape control board and drive have the exact same part numbers as the respective AT&T labeled Mountain tape drive parts. The only diff is the copyright sticker on the ROM on the controller board. Any ideas? ==Bill== -- Bill Mayhew NEOUCOM Computer Services Department Rootstown, OH 44272-9995 USA phone: 216-325-2511 wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm via internet: (140.220.001.001)
wsinpdb@wsinis02.info.win.tue.nl (Paul de Bra) (10/19/90)
In article <1990Oct18.152955.14275@uhura.neoucom.EDU> wtm@uhura.neoucom.EDU (Bill Mayhew) writes: >I've been trying to figure out a way to prevent shoe-shining of the >tape (repeated short back-and-forth movement) on a 60 meg >Sperry/CMS Wangtek tape drive on my Sys V 386 3.2.1 system. I did > >find /usr/local -name "*" -print | cpio -oc -C1024 > /dev/rmt/c0s0 According to the manual the -Cn option gives you a buffer of n BYTES, not n BLOCKS. There is a bug in the 3.2.1 cpio however which makes cpio give you a buffer of 10xn BYTES. So you really have asked for a 10k buffer. You can safely use cpio -oc -C100000 to get a 1000000 byte buffer. I always use -C131072 or -C262144 to get a multiple of 1024 bytes after the 10x bug. Paul. (debra@research.att.com)
ram@attcan.UUCP (Richard Meesters) (10/19/90)
You might want to try upping the value of the -C option from 1024 to say maybe 64k or so. Your mileage will vary and it takes a little time to find the correct block size to make your tape drive stream. Try different values. Regards, Rich.
tneff@bfmny0.BFM.COM (Tom Neff) (10/22/90)
You can also pipe everything through a big 'dd' before it hits the tape find blah blah | cpio blah blah | dd bs=2048k of=/dev/rmt/c0s0 This double buffers 2MB at a time. Watch that tape spin! -- "DO NOT, repeat, DO NOT blow the hatch!" /)\ Tom Neff "Roger....hatch blown!" \(/ tneff@bfmny0.BFM.COM