IBM DATA MIGRATION SERVICES Brochure page 7

Storage migrations made simple.
Page 7
Highlights
Offline migration methods include
restore from backup tapes and
FTP transfer.
Online migration methods include
array-based replication, volume
management or replication, and
host-based mirroring.
Restore from backup tapes
This method involves making a backup copy of data, then taking the associated
arrays and/or servers offline to ensure that no new data is added. Then, the data
is restored from the backup tapes to the new arrays and/or servers. Once the
restore process is complete, the systems are brought online. While this is a low-
cost solution, especially as nearly all organizations already use backup software,
it requires significant administrative attention and application downtime.
FTP transfer
This method involves manually copying files from the source systems to the target
systems via File Transfer Protocol (FTP). As it requires file-by-file movement, the
method is not recommended when the data contains large numbers of individual
files. FTP transfer does not provide control over the network bandwidth used for
migration, which can affect other applications and users in the network environ-
ment, nor does it enable verification of the complete transfer of data.
Online migration methods
Online migration methods generally allow data movement while applications
are up and running. Depending on the method chosen, however, these methods
can be limited to a single vendor environment. Other methods may consume
significant central processing unity (CPU) overhead, potentially resulting in
application slowdown or other disruptions.
Array-based replication
While this method allows for high service level guarantees, it requires moving
between similar storage devices, increasing costs and limiting the data center
to a single vendor.