The data migration method you select must provide the
best compromise between efficiency and impact on the system users.
The selected method should provide a simple but robust method that
minimizes user impact.
Most methods
of data migration affect the everyday operation of a computer system.
When data is moved, the data must be in a certain state, and typically
requires that updates or changes cease while the movement occurs.
Depending on the amount of data that you are moving and your migration
method, data could be unavailable for an extended period of time,
perhaps several hours. The following factors might contribute to the
migration time:
- Creating new logical volumes or file systems
- Modifying configuration files
- Receiving integrity checks
You should consider the following items to determine the best method
for your data migration:
- Management software provides simple robust methods that you can
use during production without disturbing users.
- The AIX® logical volume manager (LVM) provides methods
that you can use at any time without disrupting user access to the
data. You might notice a small performance degradation, but this is
preferable to shutting down databases or requiring users to log off
the system.
Notes: - AIX and HP-UX 11.xx ship with logical
volume management (LVM) software as part of the base operating system.
LVM provides complete control over all disks and file systems that
exist on an AIX system. HP-UX has similar volume management
software.
- Sun Microsystems has a basic volume management product called
Solstice, which is available for the Solaris systems.
- Linux systems also use the LVM.
- Methods that use backup and restore procedures have the most impact
on the system usage. They require that databases and file systems
be in quiescent states to ensure a valid snapshot of the data.