IBM SC34-7012-01 manual Tier 0-3 solutions

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 20 summarizes the tier 3 solution.

Standby Site

Approach	Recovery
Backups kept off-site	Standby site, plus bulk
Procedures and inventory	data transfer costs
off-site	Recovery in hours
Recovery - restore system
and data, reconnect to
network

Figure 20. Disaster recovery tier 3: electronic vaulting

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:

vFaster recovery, as the data does not have to be retrieved from off-site and down-loaded.

vNo 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.

Tier 0–3 solutions

Tiers 0 to 3 cover the disaster recovery plans of many CICS users. With the exception of tier 0, they employ the same basic design using a point-in-time copy of the necessary data. That data is then moved off-site to be used when required after a disaster.

Figure 21 on page 229 summarizes the solutions for tiers 0 through 3, and shows the approximate time required for a recovery with each tier of solution.

228CICS TS for z/OS 4.1: Recovery and Restart Guide