Tape performance

Wm E. Davidsen Jr davidsen at sixhub.UUCP
Sun Jun 10 23:31:33 AEST 1990

  I have noticed that the performance of tape can be hurt (a lot) by
running find with the dump process. That is:

        find /usr2 -print | cpio -oc > /dev/xtape

type stuff. By putting the list of files in a file, directory reads are
minimized and the disk has a better chance of keeping the tape
streaming. Another suggestion, minimize reads to the filename file.

        find /usr2 -print > /tmp/files.usr2
	dd if=/tmp/files.usr2 ibs=20k | cpio -oc > /dev/xtape

Note that by says "ibs" rather than "bs" dd will use two buffers, and
there will be 512 bytes of filenames left to cpio while dd refills the
names buffer. You can make the "ob=" size anything smaller than ib, and
still get this.
bill davidsen - davidsen at sixhub.uucp (uunet!crdgw1!sixhub!davidsen)
    sysop *IX BBS and Public Access UNIX
    moderator of comp.binaries.ibm.pc and 80386 mailing list
"Stupidity, like virtue, is its own reward" -me

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