Use of DB2 purescale with SAP Applications December, 2013 Customer
SAP Applications on DB2 purescale End users Can use SAP log-on groups to direct similar work to same set of servers Central Services Application Servers Application Servers Application Servers SAP application servers Are connected to a DB2 member, based on central configuration file Automatic fail-over and fail-back in case of a member failure Cluster Services Member 1 Member 2 Cluster Caching Facility Member n High speed interconnect DB2 purescale cluster Central locking and cache coherency (cluster caching facility) High-speed communication, exploiting RDMA Built-in HA through DB2 built-in cluster manager Data resides in DB2 built-in cluster file system Shared Disks 2013 SAP AG. All rights reserved. Customer 2
Client Affinity Setup Centralized connectivity setup Every SAP application server has a primary (preferred) DB2 member and a list of fail-over alternatives Assured client affinity: All connections of one SAP application server will equally and automatically db2dsdriver.cfg Application Server 1 Application Server 2 fail-over in case of member unavailability Fail-back when the primary member becomes available again Connectivity is centrally configured at: $(DIR_GLOBAL)/db6/db2dsdriver.cfg Applies to AS ABAP and AS Java Member 1 Cluster Caching Facility Member 2 Two types of connectivity setups Simple, out-of-the-box configuration: DB2 managed round-robin assignment User-defined setup for advanced DBAs Shared Disks 2013 SAP AG. All rights reserved. Customer 3
Details: Round-Robin Connectivity Setup <configuration> <dsncollection> <dsn alias="co1" name="co1" host="db6m1.wdf.sap.corp" port="5912" /> </dsncollection> <databases> <database name="co1" host="db6m1.wdf.sap.corp" port="5912"> <acr> <parameter name="enableacr" value="true"/> <parameter name="enableseamlessacr" value="true"/> <parameter name="affinityfailbackinterval" value="5"/> <alternateserverlist> <server name="member_1" hostname="db6m1.wdf.sap.corp" port="5912" /> <server name="member_2" hostname="db6m2.wdf.sap.corp" port="5912" /> <server name="member_3" hostname="db6m3.wdf.sap.corp" port="5912" /> </alternateserverlist> <clientaffinityroundrobin> <client name="sap_as_1" hostname="db6as1.wdf.sap.corp" /> <client name="sap_as_2" hostname="db6as2.wdf.sap.corp" /> <client name="sap_as_3" hostname="db2as3.wdf.sap.corp" /> </clientaffinityroundrobin> </acr> </database> </databases> <parameters> <parameter name="commprotocol" value="tcpip"/> </parameters> </configuration> Highlights Simple out of the box configuration No user interaction required Configuration details affinityfailbackinterval Fail-back check interval in seconds alternateserverlist List of all DB2 members clientaffinityroundrobin List of SAP application servers for round-robin assignment Resulting connectivity setup Primary 1st fail-over 2nd fail-over sap_as_1 member_1 member_2 member_3 sap_as_2 member_2 member_3 member_1 sap_as_3 member_3 member_1 member_2 2013 SAP AG. All rights reserved. Customer 4
Details: User-defined Connectivity Setup <configuration> <dsncollection> <dsn alias="co1" name="co1" host="db6m1.wdf.sap.corp" port="5912" /> </dsncollection> <databases> <database name="co1" host="db6m1.wdf.sap.corp" port="5912"> <acr> <parameter name="enableacr" value="true"/> <parameter name="enableseamlessacr" value="true"/> <parameter name="affinityfailbackinterval" value="5"/> <alternateserverlist> <server name="member_1" hostname="db6m1.wdf.sap.corp" port="5912" /> <server name="member_2" hostname="db6m2.wdf.sap.corp" port="5912" /> </alternateserverlist> <affinitylist> <list name="as_group_1" serverorder="member_1,member_2" /> <list name="as_group_2" serverorder="member_2,member_1" /> </affinitylist> <clientaffinitydefined> <client name="sap_as_1" <client name="sap_as_2" </clientaffinitydefined> </acr> </database> </databases> hostname="db6as1.wdf.sap.corp" listname="as_group_1" /> hostname="db6as2.wdf.sap.corp" listname="as_group_2" /> <parameters> <parameter name="commprotocol" value="tcpip"/> </parameters> </configuration> Highlights Allows individual and customized setups Targeted at experienced DBAs Configuration details affinityfailbackinterval Fail-back check interval in seconds alternateserverlist List of DB2 members affinitylist Lists of member orders clientaffinitydefined Assignments of SAP application servers to an affinitylist Resulting connectivity setup List Primary 1st fail-over sap_as_1 as_group_1 member_1 member_2 sap_as_2 as_group_2 member_2 member_1 2013 SAP AG. All rights reserved. Customer 5
purescale Support in SWPM DB2 purescale Topology Changes Migration from ESE to purescale Add/drop DB2 members Add/drop cluster caching facility Creation and update of db2dsdriver.cfg SAP Topology Changes Installation of additional SAP instances De-installation of SAP instances Includes update of db2dsdriver.cfg 2013 SAP AG. All rights reserved. Customer 6
Handling of Unplanned Outages: DB2 Members X 100% Data in-flight on failed member Member restart time Data availability Connections from SAP application servers automatically fail over to other members Only data that was in-flight data at the failed member is locked until member restart completes. All other data and all other members remain fully available Automatic member restart Attempt restart on member's home host If restart is not possible on the member's home host, DB2 will automatically perform the restart on another host DB2 will bring the member up at its home host as soon as it becomes available again Connections from SAP application servers automatically fail back to the member at transaction boundaries, invisible to the end users 2013 SAP AG. All rights reserved. Customer 7
Handling of Unplanned Outages: Cluster Caching Facility 100% Lock rebuild X Data availability time Failure of primary cluster caching facility Secondary cluster caching facility takes over Very short period (typically seconds) where CF service is suspended during switchover to secondary Members continue running; if they request CF, those requests will simply take a few more seconds to complete No errors are returned to the members No loss of in-flight transactions Failed cluster caching facility will automatically be brought up as secondary once its home host becomes available again Failure of secondary cluster caching facility Likely not perceived (very short hiccup) No loss of in-flight transactions Failed cluster caching facility will automatically be brought up as secondary once its home host becomes available again 2013 SAP AG. All rights reserved. Customer 8
Handling of Planned Outages (Maintenance) Maintenance of a DB2 member Transactions are transparently drained out from the member X X Connections from SAP application servers switch over to other members at transaction boundaries, invisible to the end users Once DB2 member maintenance is completed, the member is brought up again Connections from SAP application servers switch back to the member at transaction boundaries, invisible to the end users 100% Data remains fully available Data availability time Maintenance of a cluster caching facility For maintenance of current primary: Initiate role switch (secondary will take over) Cluster caching facility is taken out of the cluster and maintenance conducted Cluster caching facility is integrated into the cluster again 2013 SAP AG. All rights reserved. Customer 9
DB2 built-in High Availability Traditional HA versus DB2 purescale Shared Disk HA Active/passive solution Requires no CPU cycles on standby Medium-fast fail-over Rolling OS, HW and DB2 Fix Pack update DB2 High Availability Disaster Recovery (HADR) Active/semi-active solution Protection against disaster Very fast failover Rolling OS, HW and DB2 Fix Pack update DB2 purescale Active/active: Database is distributed over several servers Scaling across multiple servers Continuous availability Stealth OS, HW and DB2 Fix Pack maintenance 2013 SAP AG. All rights reserved. Customer 10
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