Scalability and performance

z/OS® Communications Server includes the following enhancements for scalability and performance:
  • IWQ support for IPSec - z/OS Communications Server is enhanced to support inbound workload queueing for IPSec workloads for OSA-Express in QDIO mode. Inbound workload queueing uses multiple input queues for each QDIO data device (subchannel device) to improve TCP/IP stack scalability and general network optimization. To implement the performance improvements for IPSec workloads, enable inbound workload queueing to process IPSec, EE, sysplex distributor, and streaming bulk data traffic all concurrently with other types of inbound QDIO traffic. When you enable these improvements for a QDIO interface, inbound IPSec, EE, sysplex distributor, and streaming bulk data traffic are each processed on their own ancillary input queue (AIQ). All other inbound traffic is processed on the primary input queue.
    Incompatibilities: This function does not support IPAQENET interfaces that are defined by using the DEVICE, LINK, and HOME statements. Convert your IPAQENET definitions to use the INTERFACE statement to enable this support.
    Dependencies:
    • This function is limited to OSA-Express6S Ethernet features or later in QDIO mode running on IBM z14™. For more information about the QDIO inbound workload queueing function and the OSA-Express features that support it, see QDIO inbound workload queueing in z/OS Communications Server: IP Configuration Guide. See the 3906DEVICE or 3907DEVICE Preventive Service Planning (PSP) bucket for more information.
    • This function is supported only for interfaces that are configured to use a virtual MAC (VMAC) address.

    When change was introduced: z/OS V2R3 with the PTF for APAR PI77649

  • Improved control over default VTAM VIT options - Two levels of operator control are provided for managing VTAM Internal Trace (VIT) internal mode record collection:
    • You can use “Full VIT control” to control the use of all VIT options, at any time, using VTAM start options or the MODIFY TRACE and MODIFY NOTRACE commands. This includes the ability to disable all internal mode VIT recording. The DISPLAY TRACE command always displays the current settings of all VIT options.
    • You can use “Base VIT control” to allow VTAM to enforce that certain VIT options (API, CIO, MSG, NRM, PIU and SSCP) remain active at all times. The DISPLAY TRACE command displays the settings of these VIT options only if you have explicitly enabled the options, otherwise the settings are not displayed. This is the default behavior, and this was the only level of VIT control provided originally.
    Restriction: The two levels of VIT control apply to internal mode recording only. External mode recording of VIT records is unchanged regardless of the level of VIT control used for internal mode recording.

    When change was introduced: z/OS V2R3 and with the PTF for APAR OA50271 for z/OS V2R2

  • Sysplex-wide security associations (SWSA) scalability improvement - Sysplex-wide security associations (SWSA) scalability is improved by increasing the number of lists that can be configured for the EZBDVIPA coupling facility structure. In previous releases, the EZBDVIPA structure had a fixed number of lists (2048 lists). With this enhancement, the number of lists in the EZBDVIPA structure can be configured with up to 16,384 lists. This allows more IPSec security associations to be distributed and taken over.
    Restriction:
    • All VTAMs in a sysplex or a VTAM subplex must be at z/OS V2R3 or later before the number of lists for an EZBDVIPA structure can be increased above 2048 lists.
    • The number of lists that are configured for an EZBDVIPA structure must be the same for all VTAMs in a sysplex or a VTAM subplex. If the configured number of lists is different, the actual number of lists is unpredictable. IPSec distribution and takeover data can be inaccessible to some TCP/IP stacks in the sysplex or VTAM subplex, potentially resulting in errors.

    When change was introduced: z/OS V2R3

Reference information: See the following topics in z/OS Communications Server: New Function Summary for detailed descriptions that include any applicable restrictions, dependencies, and steps on using the functions:
  • IWQ support for IPSec
  • Improved control over default VTAM VIT options
  • Sysplex-wide security associations (SWSA) scalability improvement