Disaster recovery
The plans, copies of data and second systems that let an organisation keep running if a whole data centre is lost.
Also written DR, GDPS, RPO, RTO, DR test, failover
Disaster recovery, or DR, is how an organisation keeps working if a data centre is lost, for example to a fire, a flood or a long power cut. For a bank, being without its systems for even a few hours is a serious problem, so DR is planned and tested carefully.
The basis is copies of data at a second site. Disk systems can copy every change to another site as it happens, or a few seconds behind. Backups on tape, or virtual tape, are also kept away from the main site. Automation software, such as IBM's GDPS, can manage these copies and restart the systems at the second site.
Two numbers describe a DR plan. The recovery point objective, RPO, is how much recent data the organisation could lose. The recovery time objective, RTO, is how long it may take to be running again.
Sites run DR tests regularly, moving work to the second site and back to prove that the plan works. For operations and support staff, a DR test is a long, carefully scripted day, and the runbook is followed step by step.
Where can I learn this hands-on?
Right here, at ZedBank. You take a junior job at a simulated bank and learn each part of the work by doing it, with Zed beside you. There's nothing to install.
Start at ZedBankRelated
- SysplexA group of mainframe systems joined together so they behave as one, sharing work and data so that no single failure stops the service.
- DASDDirect access storage device, the mainframe term for disk storage.
- TapeStorage that holds data in sequence on cartridges, used on the mainframe for backups, archives and large files read from start to end.
- RunbookThe written procedure for operating a system or responding to a known failure, step by step.
- Production supportKeeping live systems running: diagnosing failures, fixing what broke, and getting the service back.
- OperatorThe person who watches the running systems, responds to messages, and starts, stops and recovers work.