Path: utzoo!attcan!uunet!snorkelwacker!bu.edu!dartvax!avalon.dartmouth.edu!steve
From: steve@avalon.dartmouth.edu (Steve Campbell)
Newsgroups: comp.unix.ultrix
Subject: Re: Why isn't dump maximally efficient with TK70 tapes?
Message-ID: <22663@dartvax.Dartmouth.EDU>
Date: 11 Jun 90 20:17:43 GMT
References: <1990Jun8.014252.15749@watcgl.waterloo.edu> <12420@cbmvax.commodore.com>
Sender: news@dartvax.Dartmouth.EDU
Organization: Dartmouth College, Hanover, NH
Lines: 22

In article <12420@cbmvax.commodore.com> grr@cbmvax (George Robbins) writes:
>Mostly that dump doesn't document the -b switch to let you specify a more
>efficient block size and restore doesn't support it, which makes it a
>pain to restore tapes with non-standard block sizes.

It sure is a pain.  Still you can use the -b option on dump and then let
dd do the unblocking on restores.  For example:

	dump 0fdb /dev/rmt0h 6250 64 /dev/rra1a

and then for restores:

	dd if=/dev/rmt0h bs=64k | restore if -

This works and gets much better performance out of a TU81.  In one case the
elapsed time dropped by about 35%.  I haven't tried it on multi-volume dumps.

Would someone familiar with version 4.0 care to comment on whether the -b
option will be documented and supported by restore in that version?

						Steve Campbell
						Dartmouth College