Today, disaster backup is an important issue, and how to ensure that the data center as soon as possible recovery operations after a certain level of failure and disaster, is essential for some of the business continuity sensitive enterprise.
Disaster backup most use the city off-site disaster recovery. Depending on the user’s business difference, the designed disaster recovery solution is very different. For remote disaster recovery solutions, some host-based or based on storage replication via TCP / IP reliaze offsite backup.
However,TCP / IP network is not very stable, may occur packet loss, so to achieve copy need a variety of ways such as fiber optic channels or ATM technology, that can reach the long-distance disaster recovery system, from more than ten kilometers to tens of kilometers or even thousands of kilometers can achieve both disaster recovery system.
This technology is called DWDM multiplexing in fiber optic network. Let’s see DWDM how to work in a disaster recovery environment via a specific case of disaster recovery.
DWDM disaster recovery applications
We see a typical SAN environment, we have 2 hosts, 2 SAN switches, storage, they might HA, RAC environment may be stand-alone, this is not important now. Importantly, the SAN environment, we are generally configured locally, similar to a local area network, we have adopted the general line of fiber-optic connections can build a SAN environment.
Now, because business needs, you must consider disaster recovery. You want make these two machines, two storage distributed in a different room, however, these two rooms separated by more than 10KM.If were forcibly opened, we will seelike that:
We can see there are a lot of fiber needs to be pulled very long, but these long fiber must be rely on the carriers generally to pull. Moreover, more of the optical fiber will bring the greater the cost. Then do we do not have a good solution to this? Yes, this is DWDM fiber optic multiplexing (DenseWavelength-Division Multiplexing, high-density multi-work-point filter), according to the WDM development over DWDM technology has been widely used for many years, using DWDM SAN diagram will become like that:
The principles of DWDM principles
As for the Fiber multiplexing, long-distance fiber-optic lines now need only one fiber, just to consider the redundancy, as long as the two fiber. After this, the entire structure has not changed, you can think of that fiber line run multiple fiber you need.
How does DWDM achieve it? We can look at a schematic.
The DWDM is actually using different wavelengths in a fiber optic line to pass different data, to simulate different channels actually look like different fiber communication. As long as the wavelength is not same, so DWDM casually can multiplexing dozens of channels in a fiber optic line At laboratories can even reuse the thousands of channels.
So with DWDM access to remote storage via SAN becomes very easy, remote RAC is no longer a dream. In fact, through this DWDM technology, and then use the volume replication to disaster recovery technology has been officially in use in the domestic banking institutions. Moreover, the remote RAC, a new disaster recovery plan, which can achieve high availability and Load balancing, and disaster recovery program, also consider using in the company.