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From: steve@avalon.dartmouth.edu (Steve Campbell)
Newsgroups: comp.unix.ultrix
Subject: copying "a" partitions
Message-ID: <20692@dartvax.Dartmouth.EDU>
Date: 18 Mar 90 16:06:25 GMT
Sender: news@dartvax.Dartmouth.EDU
Organization: Dartmouth College, Hanover, NH
Lines: 17

Having a disk partition table on each disk pack (see chpt(8)) is a great
improvement over having the partition layout coded into the driver, but 
there is one little drawback.  It used to be possible to make backup
copies of the root partition, 0a, by using dd(1) to copy /dev/r??0a to
/dev/r??1a or any other "a" partition.  This was fast (less than a minute
on RA81's) and on several occasions saved me many hours of work.  But now
with the disk partition table in the superblock, you can't use dd(1) this
way unless the two disks have identical partition tables, since the
tables get copied, too, and...  

I haven't yet found a good alternative for making disk-to-disk copies
of the root file system.  Pipes using tar(1) or dump/restore are much
slower and have other disadvantages like too much operator intervention
being required.  Does anyone have any suggestions?

						Steve Campbell
						Dartmouth College