Tier 3 - electronic vaulting

Tier 3, like tiers 1 and 2, provides a basic level of disaster recovery. You will lose data in the disaster, perhaps a considerable amount of data.

The advantage of tier 3 is that you should be able to provide a service to your users quite rapidly. You must assess whether the loss of data will prevent your company from continuing in business.

Figure 1 summarizes the tier 3 solution.
Figure 1. Disaster recovery tier 3: electronic vaulting
This illustration shows two data centers—the primary and a remote standby site, with a telecommunications link between the two. The other points made by this figure are discussed in the following text.

Tier 3 is similar to tier 2. The difference is that data is electronically transmitted to the hot site. This eliminates physical transportation of data and the off-site storage warehouse. The same process is used to backup the data, so the same primary site availability issues exist in tier 3 as in tiers 1 and 2.

The benefits of tier 3 are:
  • Faster recovery, as the data does not have to be retrieved from off-site and down-loaded.
  • No need to ship the backups manually to a warehouse and store them.

The drawbacks are the cost of reserving the DASD at the hot standby site, and that you must have a link to the hot site, and the required software, to transfer the data.

Procedures and documentation still have to be available at the hot site, but this can be achieved electronically.