i Can Blog Archive

Techical Tips for i by Dawn May


PowerHA for SMB

I’ve heard many clients state that PowerHA is too complex or expensive for the small-to-medium IBM i environments, so this week, Steve Finnes is here on ‘i Can’ to answer a few questions.

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Leveraging SSDs and IASPs with BRMS Migration

One significant change in IBM i 7.2 is the modernization of storage tiering in the BRMS migration function. In prior releases, the migration function in BRMS works only for library migration between auxiliary storage pools (ASPs) based on the specified policies for frequency of use. However, in IBM i 7.2 with PTF SI57831 applied, the BRMS migration function is enhanced to support the migration to independent ASPs (IASPs), migration of *LNK lists for IFS files, and migration of database files to different SSD and HDD storage tiers within the same ASP.

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SQL CPU Utilization

SQL CPU Utilization was introduced in the IBM i 7.2 release. This metric helps you discover how much of your CPU is being used by SQL operations, and is a starting point to determine if your CPU utilization is due to SQL or other work on the system.  This metric is available on a per-thread basis and aggregated for the partition as a whole.

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What Happened to the IBM i PCRM?

The Performance Capabilities Reference Manual (PCRM) was THE resource many used when they needed to know something about IBM i performance. That something could be information about performance test results, I/O performance information, performance considerations for IPL, save/restore, partitioning, CPW ratings and many other miscellaneous topics. The last large version of the PCRM was published for IBM i 7.1 in August of 2013. When IBM i 7.2 became available in spring of 2014, that update of the PCRM was substantially smaller.

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Routing Work to Subsystems

In the blog Route Db2 Requests to a Specific Subsystem, I wrote how you can use the QSYS2.SET_SERVER_SBS_ROUTING procedure to route work for database queries using the QZDASOINIT or QRWTSRVR server jobs to customized subsystems. This is a new way to route work based upon the requesting user profile that augments the other ways you can route work to subsystems. 

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Route Db2 Requests to a Specific Subsystem

We all know that a key advantage to IBM i is the work management capabilities, in particular the ability to segregate work into different subsystems.  One of the more challenging areas for this, however, has been prestart server jobs.  By default, these prestart jobs run in the QUSRWRK subsystem.  You can configure the subsystem in which these prestart server jobs run by routing the requests based upon the client IP address, but that’s often not sufficient.  Many requests may come from one IP address, or perhaps you would like to segregate work based upon some other criteria – for example, the requesting user profile.

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