IBM SC34-7012-01 manual Disaster recovery tier 1 physical removal

Approach	Recovery
Backups kept offsite	Relatively low cost
Procedures and inventory	Difficult to manage
offsite	Most important applications
Recovery - install required	resolved first
hardware, restore system and	Recovery possible, but may
data, reconnect to network	take a long time

Figure 18. Disaster recovery tier 1: physical removal

Your disaster recovery plan has to include information to guide the staff responsible for recovering your system, from hardware requirements to day-to-day operations.

The backups required for off-site storage must be created periodically. After a disaster, your data can only be as up-to-date as the last backup—daily, weekly, monthly, or whatever period you chose—because your recovery action is to restore the backups at the recovery site (when you have one).

This method may not meet your requirements if you need your online systems to be continuously available.

vIf you require data from two or more subsystems to be synchronized, for example, from DB2 and VSAM, you would have to stop updates to both, then copy both sets of data.

vSuch subsystems would both be unavailable for update until the longest running copy is finished.

vIf you require a point-in-time copy for all your data, your application may be unavailable for updates for a considerable time.

The major benefit of tier 1 is the low cost. The major costs are the storage site and transportation.

The drawbacks are:

vSetting up a computer floor, and obtaining the necessary hardware after a disaster can take a long time.

vRecovery is to the point in time of your last backups. You have no computer record, such as forward recovery logs, of any transactions that took place after these backups were taken.

vThe process is difficult to manage.

vYour disaster recovery plan is difficult to test.

226CICS TS for z/OS 4.1: Recovery and Restart Guide