Re: fastest way to copy a disk

From: Akop Pogosian (akopps+usenet_at_ocf.berkeley.edu.remuvthis.com)
Date: 06/25/04 

Date: Thu, 24 Jun 2004 23:08:41 +0000 (UTC)

Martin Paul <map@par.univie.ac.at> wrote:
> G Dahler <yellow-shark@spamex.com> wrote:
>> What is the fastest way to migrate all the data ?

> In addition to what the other posters already told you - if you
> want to keep the time window in which the filesystems are not accessible
> as short as possible, it makes sense to make a copy with e.g. a
> tar cf | tar xf while the system is still up, and later use rsync
> to just copy files which have changed in the meantime.

I would recommend this too. However, there are some pitfalls when
using rsync. First, the -a option (archive copy) does not preserve
hard links, so make sure you also use -H option if you care about
preserving hard links. Second, rsync does not preserve any
non-standard file attributes. In particular, ACLs will not be
preserved. You would have to write some sort of script to restore ACLs
or use ufsdump. If you don't care about ACLs then rsync is a good way
to move a large, frequently updated file system to new disks with very
little downtime. If you do use ufsdump, perhaps it would be faster to
turn off logging and use Casper ***'s fastfs
(ftp://ftp.wins.uva.nl/pub/solaris/fastfs.c.gz) to enable delayed I/O
on the new file system. 

-- 
Akop Pogosian
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