1. Determining BC/DR Methods
Recovery Time Objective – (RTO)
Time needed to recover from a disaster
How long can you afford to be without your systems
Recovery Point Objective – (RPO)
Age of the data you want the ability to restore in the event of a disaster
Any data created or modified inside your recovery point objective will be either lost or must be recreated during a recovery
Network Recovery Objective – (NRO)
Time required to recover or fail over network operations
Completely Duplicated/
Interconnected hot -
site
Remote Disk Mirroring
Disk Mirroring
Shared Disk
Single Disk Copy
Electronic Vaulting
Tape On
Tape Back up
Off
site (trucks)
Disk Consolidation
More
Less
Delayed
Immediate
Mission Critical
Applications
Amount
of Data
Recovery
Time
Importance of
Data
GDPS/STP
Metro Mirror
Global Mirror
Global Copy
Tier 7
Tier 6
Global Mirror for zSeries
Tier 4
Critical
Non Critical
Sumberdari :
collaboration.greatplains.net/wiki/images/a/aa/SAN101.ppt

2. Disaster Recovery Concepts
Secs
Mins
Hrs
Days
Wks
Recovery Point
Recovery Time
Recovery Point Objective (RPO) – Point in time to which applications data must be recovered to resume business transactions Recovery Time Objective (RTO) – Maximum elapsed time required to complete recovery of application data

3. Recovery Point Objective (RPO)
Business needs drive the technology choice
Secs
Mins
Hrs
Days
Wks
Recovery Point
Recovery Time
Tape Backup
Periodic Replication
Asynchronous Replication
Synchronous Replication

4. Recovery Time Objective (RTO)
Business needs drive the technology choice
Secs
Mins
Hrs
Days
Wks
Recovery Point
Recovery Time
Global Clustering
Manual Migration
Tape Restore
Recovery Time includes:
Fault detection
Recovering data
Bringing apps back online

5. Synchronous Mirroring
Receipt acknowledgment is provided by target back to cache of source
Ending status is presented to host / server
DS3, OC-3/12/48
STM-1/4/16
MAN
WAN
I/O write received from host / server into cache of source
CN 2000
CN 2000 OR
OC-3/12/48
STM-1/4/16
Synchronous Mode
Synchronous mode is most appropriate for an implementation that requires data at the recovery site to be continuously synchronized to the source. In the event of a disaster, the recovery data is accurate up to the last transaction and is immediately available for use. Synchronous Mode provides mirroring of data between the source disk and the target disk system. In this mode, data is first written to the source system and then to the target system. An acknowledgment must be received at the source before a subsequent host I/O operation is allowed.
Source
Target
I/O is transmitted to the cache of the target

6. Asynchronous Mirroring
Source sends only final set of updates to target
I/O write received from host / server is collected into Source
DS3, OC-3/12/48
STM-1/4/16
MAN
WAN
CN 2000 OR
Ending status is presented to host / server
CN 2000
OC-3/12/48
STM-1/4/16
Source
Target
SRDF/Asynchronous (SRDF/A)
SRDF/A is an innovative approach to asynchronous replication that delivers a consistent and restartable remote copy of production data over extended distances and with minimal impact on host applications. Its unique Delta Set architecture provides efficient utilization of bandwidth requirements while minimizing data exposure without sacrificing performance. Delta Sets are cache-resident collections of dependent writes that have occurred within a specific period of time. Delta Sets also provide effective utilization of bandwidth between sites in two ways:
• Locality-of-reference
• Sizing communication links to average write workloads
With traditional asynchronous solutions, every write must be time-stamped, sequenced, and sent to the remote site. Every write is treated as a discrete write and must be moved over the communication link. Through locality-of-reference, Delta Sets allow data to be rewritten, so only the final set of updates is sent to the remote site.
Another bandwidth savings provided by SRDF/A is the ability to size communication links to average write workloads rather than peak workloads. Peak workloads might only occur for a brief period while batch updates are occurring or some other period of time when processing activity is high. Because Delta Sets are collecting the new writes in cache while experiencing locality-of-reference benefits, SRDF/A is able to ride through periods of increased write activity more efficiently.
Target receives updates and applies the writes to the volume