Copy Services
With the increased emphasis on Business Continuity and Disaster Recovery (BC/DR) more and more installations use Copy Services solutions to maintain a second data copy in a remote data center. The interest in Copy Services solutions not only follows from internal business risk assessments, but is also a result of evolving regulatory requirements.
Copy services solutions can be categorized into two groups: synchronous and asynchronous solutions.
Synchronous Copy Services
Synchronous copy services solutions are those such as EMC SRDF/S, IBM PPRC (Metro Mirror), and some types of HDS TrueCopy.
With synchronous Remote Copy, each write operation to the 'primary' controller is replicated real-time to a secondary controller in another location. The primary controller will only complete its write operation after the secondary controller has acknowledged successful receipt of the data.
Asynchronous Copy Services
Asynchronous copy services solutions are offered by EMC SRDF/A, IBM Global Mirror and Global Mirror for zSeries (a.k.a. XRC), and some types of HDS TrueCopy.
With asynchronous solutions, the completion of the write to the primary is independent of the copy to the secondary. The main benefit is that much greater distances can be spanned; while synchronous solutions are limited to 100 km, asynchronous solutions can easily support thousands of kilometers, as the signal propagation delay does not impact response time.
On our web site we provide a short description of most current copy services solutions available from the vendors.
Click on one of the technologies below for more information:
| Copy Services Type |
IBM | EMC | HDS |
| Synchronous | Metro Mirror (PPRC) | SRDF/S | TrueCopy |
| Asynchronous | Global Mirror | SRDF/A | TrueCopy |
| zSeries Global Mirror (XRC) |
