Continuous availability benefits of pureScale now available in a new low cost DB2 offering
January 20, 2015 Leave a comment
Today, IBM has announced a set of new add-on offerings for DB2, which includes the IBM DB2 Performance Management Offering, IBM DB2 BLU Acceleration In-Memory Offering, IBM DB2 Encryption Offering, and the IBM DB2 Business Application Continuity Offering. More details on these offerings can be found here. Generally speaking, the intention of these offerings is to make some of the significant capabilities and features of DB2 available as low cost options for those not using the advanced editions of DB2, which already include these capabilities.
If you’ve read any of my past posts you know that I’m a big proponent of DB2’s pureScale technology. And staying true to form, the focus of my post here is on the IBM DB2 Business Application Continuity (BAC) offering, which is a new deployment and licensing model for pureScale. This applies to DB2 10.5 starting with fix pack 5 (the current fix pack level released in December 2014).
For more information on DB2 pureScale itself, I suggest taking a look here and here. But to boil it down to a few major points, it’s an active/active, shared data, clustering solution that provides continuous availability in the event of both planned and unplanned outages. pureScale is available in the DB2 Advanced Workgroup Server Edition (AWSE) and Advanced Enterprise Server Edition (AESE). Its architecture consists of the Cluster Caching Facilities (CF), which provide centralized locking and data page management for the cluster, and DB2 members, which service the database transaction requests from applications. This multi-member architecture allows workloads to scale-out and workload balance across up to 128 members.
While that scale-out capability is attractive to many people, some have told me that they love the availability that pureScale provides but that they don’t have the scalability needs for it. And in this case they can’t justify the cost of the additional software licenses to have this active/active type of environment – or to even move from their current DB2 Workgroup Server Edition (WSE) or Enterprise Server Edition (ESE) licensing up to the corresponding advanced edition that contains pureScale.
This is where BAC comes in. With BAC – which is a purchasable option on top of WSE and ESE – you can create a two member pureScale cluster. The difference, and what makes this offering interesting and attractive for some, is that the cluster can be used in an active/active way, but it’s licensed as an active/passive cluster. Specifically, one member of the cluster is used to run your application workloads and the other member is available as a standby in case that primary member fails or has to be brought down for maintenance. But isn’t that passive? No… and the reason is that this secondary member doesn’t just sit idle waiting for that to happen. Under the BAC offering terms, you are also allowed to run administrative operations on this secondary “admin” member. In fact, you are allowed to do all of the following types of work on this member:
- Backup, Restore
- Monitoring (including DB2 Explain and any diagnostic or problem determination activities)
- Execution of DDL
- Database Manager and database configuration updates
- Log based capture utilities for the purpose of data capture
- Security administration and setup
By offloading this administrative work off of the primary member, you leave it with more capacity to run your application workloads. And with BAC, you are only fully licensing the one primary member where your applications are running (for either WSE or ESE plus BAC). The licensing of the secondary member, on the other hand, falls under DB2’s warm/idle standby licensing which means a much reduced cost for it (e.g. for PVU pricing the secondary member would only be 100 PVUs of WSE or ESE plus 100 PVUs of BAC). For more details on actual software costs, please talk to your friendly neighborhood IBM rep.
And because this is still pureScale at work here, if there’s a failure of the primary member, the application workloads will automatically failover to the secondary member. Likewise, the database will stay up and remain accessible to applications on the secondary member when the primary member undergoes maintenance – like during a DB2 fix pack update. In both of these cases the workload is allowed to run on the secondary member and when the primary member is brought back up, the workloads will failback to it. All of the great availability characteristics of pureScale at a lower cost!
If you contrast this with something like Oracle RAC One Node, which has some similar characteristics to IBM DB2 BAC, only the primary node (instance) in Oracle RAC One Node is active and the standby node is not. In fact, it’s not even started until the work has to failover, so there’s a period of time where the cluster is completely unavailable. So a longer outage, slower recovery times, and no ability to run administrative work on this idle node like you can do with BAC.
Sounds great, right?
And for those of you that do want the additional scale-out capability, but like the idea of having that standby admin member at a reduced cost, IBM has thought of you too. Using AWSE or AESE (the BAC offering isn’t involved here), you can implement a pureScale cluster with multiple primary members with a single standby admin member. The multiple primary members are each fully licensed for AWSE or AESE, but the single standby admin member is only licensed as a passive server in the cluster (again, using the PVU example that would only be 100 PVUs of either AWSE or AESE). In this case, you can do any of that administrative work previously described on the standby member, and it’s also available for workloads to failover to if there are outages for one or more of the primary members in the cluster.