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Getting Started with Flash Express on zEnterprise EC12
Caroline Exum 270004MPQK firstname.lastname@example.org | | Tags:  sm appinfra economics zenterprise systemz storage zec12 data flash flash_express bao security flashexpress io | 4,315 Visits
Storage-class memory (SCM), also known as Flash Memory, was introduced on zEnterprise EC12 processor. The current exploitation of SCM is for Auxiliary Storage paging requests, as a alternative to DASD page data sets. There is still a requirement to have a minimum of one Local Page data set defined.
Once the pairs are created, the next step is to allocate flash to LPARs. This is accomplished by using the Manage Flash Allocation panel on the Support Element or HMC. Flash has to be allocated in 16G increments, and the allocation panel allows you to set a initial allocation value and a maximum value. The maximum value that can be set is the theoretical value of 6544G, even when only 1 Pair of Flash cards is installed. There are two ways you can configure the Flash Memory online to zOS LPAR:
Another nice feature is that you can change the maximum value dynamically while the LPAR is IPLed, in case you outgrow the initial maximum value that was set.
If your paging increases such that you start running into Auxiliary Storage shortage, you can easily bring more Flash online to the LPAR by simply issuing CONFIG SCM(xxxxM|G|T),ONLINE.
CONFIG SCM(xxxxM|G|T),OFFLINE is coming in 2013, so the only way to remove or reduce the amount of Flash currently is by deactivating the LPAR using the HMC or Support Element.
One of the ways you can observe your Flash Memory usage is by issuing D ASM command:
RMF Monitor II also provides a panel for SCM usage, in addition to Post Processor reports for SCM.
A new command in support of SCM provides a display to show the amount of SCM configured. Output from D M=SCM:
D M=SCM(DETAIL) command will give you a detailed display for SCM increments.
With the introduction of Flash Memory, the number of paging data sets the customer has to provide, setup, and format will be decreased. This will simplify the number of tasks the customer has to perform to properly setup the system's paging subsystem. If a Auxiliary Storage shortage occurs, another Flash increment can be added quickly and easily, in addition to the performance improvements.
This blog post is part two of a four part series on FlashExpress from the Flash development team. Check out other posts on the Mainframe Insights blog:
Bob Fuga has been with IBM for 31 years. He has been working in SVT for past 12 years, specializing in IOS, zDAC, HCD, Coupling Facilities and IO Configurations. Bob volunteered for SCM (Flash) project and found it to be a very exciting project to work on.