SUMMARY: Fastest way to copy large filesystems

From: Matthew Atkinson (
Date: Tue Aug 25 1998 - 09:37:37 CDT

Dear All,

Thanks very much to all the kind people who advised me on the best
way to copy my large filesystem.

As a number of people mentioned, RAID-5 is slow for writes, and this
has no doubt made my problem worse, but I'm stuck with it.

The general consensus is that the best way was to use
ufsdump 0f - | (cd /target; ufsrestore xf -)
noting that I still need to use ufsrestore, not vxrestore, as I am
dependant upon dump type, not filesystem type when performing a

However, one clever chap, Scott Howard (from Australia I think) pointed
me in the direction of rsync, available from the Samba people at
This little program allows you to synchronise two filesystems, only
making amendments where necessary.

So I'm now running my ufsrestore | ufsdump, and once this is done I
will be doing regular rsyncs to keep them in step until I throw all the
users off, do one final rsync and then remount the filesystems so that
my new one becomes my master. This way my downtime will only be a few
minutes. The command I'm using is rsync -aH --delete /raid/ /newraid
where /raid is my existing 16GB filesystem, and /newraid is the copy
which will eventually take its place.

Thanks very much to all who answered, far too many to mention them all,
and particular thanks to Scott Howard (who's probably gone to bed now)


Matthew Atkinson                      Phone:  +44 (0) 1904 462120
Sun Systems Technical Administrator   Fax:    +44 (0) 1904 462111
Information Systems Team
Central Science Laboratory            E-mail:
Sand Hutton, York, YO41 1LZ, England  Web:

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