[Discuss] rsync v. cp in data migration

[gaf at blu.org (Jerry Feldman)]

On 05/23/2013 01:32 PM, Greg Rundlett (freephile) wrote:
> Suppose you have to _migrate_ 4TB of data (all of /home/*) from one host to
> a new SAN attached to a new host.  You know it's going to take time, and
> your users work around the clock so the best approach would be to do the
> migration in two steps:
>
> 1) copy all data as a way to get the "bulk" of the data migrated
> 2) disable write access to source and copy the remaining data
>
> Assume that the /home directory on the "remote" source host is mounted via
> NFS to the target host (so there is a local path to /source).
>
> Would  cp
>    cp -au /source/* /target
> be preferable to rsync?
>    rsync -vazn --checksum --progress --stats /source/ dest/
>
> This conversation
> http://unix.stackexchange.com/questions/44384/cp-or-rsync-is-cp-really-worth-it
> doesn't seem to offer clear consensus; or if it does, it's that cp can be
> used to make a phase one copy, and then (shut off write access to source)
> rsync can be used to do the final copy.
>
I just want to comment. Next month I will be moving about 4TB of data 
from my ReadyNAS 3100 to an IBM N series NAS. My plan is to copy the 
data directly from the ReadyNAS to the N series. I'm not sure what tools 
are available on N series. The ReadyNAS 3100 is a Linux system. We 
currently do a nightly backup using Tivoli Storage Manager where TSM is 
actually running on a client host not the ReadyNAS itself. So, in my 
specific case, I might be able to use TSM to restore from the backup, 
and then use rsync to synchronize before cutover. I don't want to 
require significant down time.

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
PGP key id:3BC1EB90
PGP Key fingerprint: 49E2 C52A FC5A A31F 8D66  C0AF 7CEA 30FC 3BC1 EB90