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zSeries Scalability and Availability improvements

Latest hardware and software advancements Fri Sep 26, 2014: 10:15-11:30 Track 2 Speaker : Donald Zeunert (BMC Software). zSeries Scalability and Availability improvements. Abstract / Summary.

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zSeries Scalability and Availability improvements

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  1. Latest hardware and software advancements Fri Sep 26, 2014: 10:15-11:30 Track 2 Speaker: Donald Zeunert (BMC Software) zSeries Scalability and Availability improvements

  2. Abstract / Summary • Recent IBM system and subsystem scalability improvements allow significant consolidation. • This save CPU and Memory resources • Avoids creating more server instances to manage • Bottlenecks - Faster CPUs mean everything else relatively slower • Need to look at what are the bottlenecks and what did we ignore when it was released

  3. Areas of improvements • Performance / Scalability • Hardware, Microcode, PR/SM • Software – z/OS, CICS, DB2 • Availability • Software / hardware

  4. IT Budgets – Save $ • Need to look at technology impact on Software License Costs? • New hardware or software costs money • Does it save me any?

  5. Relative speed of devicesCPU faster everything else relatively slower • RAM is now slow • > CHIP Cache on z196, EC12 • Paging devices are slower • EC12 Flash memory

  6. Topic 1 – Hardware / Microcode Performance • zEC12 Benefits • Workloads may use fewer MSUs • Warning track • Other exclusives • CF Sharing - Thin interrupts • Hiperdispatch • Why do we need ? • Parked engines

  7. z10 vs zEC12 Chip Cache • Each generation CPs getting • more levels of chip cache • More MB at each level • Chip cache hits = fewer CPU secs RNI = Ratio of Chip / local sourcing to total sourcing (Local + Remote) zEC12

  8. Disclaimer – “Your Mileage may vary” Migrating from gasoline Exotic to electric supercar will improve MPG But what if you also have an 18-wheeler

  9. zPCR Workload RNI Characteristics

  10. zEC12 – Workloads may use fewer MSUs • Onlines mayget better response, use significantly lessCPU secs and MSUs. Butdoes this help my hardware and software bills? • Yes, if onlines are driving your box capacity and 4HRA • Step 1 – Run or find your last Sub-Capacity Reporting Tool (SCRT) report and determine what hour / shift is the peak(s). • Step 2 – Determine 4HRA contributors % Batch, CICS, etc. • Step 3 – Look at zPCR chart for RNI (High?) of your workload • Step 4 – If workload has high RNI run zCPR model upgrade to zEC2 using your Hardware Capacity SMF 113s Cache stats

  11. RNI by Hour correlated with 4HRA Day shift OLTP High RNI –matches 4HRA Night shift – 4HRA lower RNI, not as CHIP cache constrained Peak 4HRA High RNI at peak MSU RNI 3:00 AM 1:00PM

  12. zEC12 – Warning Track InterruptMore consistent response time

  13. Warning Track - % Successful and Rate • High rate of WTIs / second – (typical low weight / overcommited) • Logical removed from Physical successfully > 98% of the time • making work eligible to be re-dispatched on different logical. • Provides more consistent OLTP response time WTI Metrics are in SMF70s, support to collect in; CMF PTFs BQM0868 (5.8) or BQM0867 (5.9) or RMF APAR OA37803

  14. zEC12 – Other exclusives • Storage Class Memory (SCM) – AKA Flash Express • PCIe - 1.4 TB of memory per mirrored card pair • PR/SM Absolute Capping • Expressed in terms of 1/100ths of a processor (0.01 to 255.0) • Smoother capping • 4HRA Max Spike(s) • Data Compression Express (zEDC) • (PCIe) device – Offload software compression • SMF Logstreams • Get Softinflate (OA41156 ) if machines w/o zEDC • Numerous other exploiters

  15. CF Thin interrupts – Improved Service times High Sync times = GCP Spin loop = wasted MSUs = contribute 4HRA

  16. Logical / Physical - Guaranteed Using White Space / more than guaranteed share. Impacting 4HRA? SJS* LPAR weight < 10% of 16 CPs so guaranteed < 1.6 CPs, actually max is 2 -> 3 These LPARs using about twice guarantee

  17. Guaranteed Share calculations • %MSU is % of 1 CP so work runs 100-%MSU slower than if full CP • VMR CPs are 64% slower than full due to over commit • Unless using HiperDispatch with parked CPs • Warning track helps • If not over commit can’t exceed # of CPs to LPAR • How much white space do you need?

  18. HiperDispatch – view of over commit Guaranteed 0.86 0.72 1.15 Lots of Parked Med/Low = slower effective MSUs and overhead

  19. Performance / Scalabilityimprovements in Software

  20. How does IBM charge for sub-capacity? Sub-Cap Reporting Tool (SCRT) • IBM MLC costs 30% of IT budget • Reducing 4HRA MSUs lowers bills • Paid on peak LPAR where product(s) run • Less GCP MSUs • zIIP • LPAR consolidation 4448 MSUs - CEC utilization of a LPAR w/ DB2 licensed 199 MSUs – DB2 Service class CPU (not complete DB2) But not DB2 peak

  21. DB2 Software Performance / Scalability • DB2 v10 / 11 – ( $/ MSU higher, but fewer MSUs?) • Max # concurrent threads, • zIIP offload sequential prefetch (batch) • Watch for zIIP overcommit / zIIP on GCP • IDAA – offload and WLM goal awareness • V11 DDF Enclave classification enhancements • Also requires z/OS 2.1 WLM • Package Name: 128 characters (instead of 8) • Procedure Name: 128 characters (instead of 18)

  22. DB2 V10 – Seq prefetch zIIP overcommit • DB2 V10 Sequential prefetch zIIP eligibility can overcommit zIIPs • Monitor zIIP > 50% potential for GCP • Monitor DB2 WLM Service classes w/ SMF72s or DBM1 jobs w/ SMF30s for zIIP eligible on GCP

  23. DB2 V10 – 10x more Threads per SSID • Higher concurrent threads = fewer SSIDs / LPAR

  24. Software Performance / Scalability • CICS – • TOR CPU Starvation • Threadsafe vs QR, fewer regions = less function shipping = Save CPU & memory • Convert via 80/20 rule, and whatever is left on QR runs faster • Target with CICS stats - #context switches, CPU secs

  25. CICS Scalability - L8 running threadsafe • Non-threadsafeprogram calls DB2, CICS switches from the QR TCB to an open TCB, and back to after DB2 request • Threadsafe Program stays on Open TCB until non-threadsafe CICS API call • Force to OTE / L8 w/o OPENAPI TRUE call • CONCURRENCY(THREADSAFE) and API=OPENAPI Lower QR TCB CPU Originally DB2 was only OPENAPI TRUE Now MQ, CICS/DLI, native sockets

  26. CICS TOR CPU Starvation / responsiveness • Problem from TORs and AORs running at the same dispatch priority. • AORs heavily consumes CPU. • TORs need to wait too long to receive work and return results to the caller • Especially when large # of transactions enter AORs w/o TOR • Old Circumventions: Move TORs to a service class with higher importance than AORs • Option 1 - : Exempt all regions from being managed by response time goals and classify TORs to a service class with higher importance than AORs. • Disadvantages: • Loose WLM Server management of variable dispatching priorities, memory protection, etc. • No response time data available in Service class reports • Option 2 - Exempt only AORs and move them to a service class with lower importance than the CICS service classes with response time goals. • Disadvantage: • WLM Server Mgmt lost • WLM SrvCls BTE reports for highest CPU consumption eliminated.

  27. CICS – Work Manager / Consumer Model • TORsmanaged towards the goals of the STC’s service class • WLM ensures bookkeeping of transaction completions for CICS response time for service class • CICS transactions are managed towards CICS response time goals and the • AORsResponse time goal management unchanged • Use NEW WLM SrvCls classification option “BOTH” for TORs • Define a STC service class for TORs which has a higher importance than the AORs response time goals • Retain “Manage Regions by Goals of Transaction” for AORs. Allows CICS to use similar model to WAS with DB2 / DDF. WLM classification both from APAR OA35428

  28. Software Performance / Scalability • IMS 13 - 117K trans / second , • 4x Max # PSTs, • IMS Connect WLM routing, • z/OS – • CF "fair queueing" algorithm for queued CF requests • Selection FIFO prior to APAR (OA41203) z/OS 1.12+ • Burst to single structure could negatively affect all structures. • Now allows low volume high priority signaling to get processed • SMF logstreams, SMF Compress (zEDC), • VSAM RLS based User Catalogs (enqueues < CPU) • IP - RoCE (Remote Direct Memory Access over Converged Ethernet)

  29. z/OS 2.1 VSAM RLS User Catalog Benchmarks • Help batch elapsed time when high # of temporary cataloged datasets • Reduce batch window squeeze • Possibly reduce 4HRA MSUs by moving peak CPU measured in the CATALOG, GRS, SMSVSAM, and XCFAS address spaces. Source: Terri Menendez of IBM RLS/VSAM/Catalog R&D

  30. Monitor VSAM RLS for User Catalogs • Monitor z/OS Health checkers for RLS • Enable RLS HCs • 8 RLS Msgs that go to MVS console • CF IGWLOCK00 • Monitor RLS • See SHARE RLS Performance sessions for what to monitor • True / False contention • DSN false invalidates RLS stats in SMF 42s, BP in Subtype 19

  31. Availability improvementsfrom Hardware / Software

  32. Topics - Availability • z/OS – • V2.1 Serial Coupling Facility structure rebuild • Processing, re-designed to help improve performance and availability by rebuilding coupling facility structures more quickly and in priority order. • Previously all structures rebuilt in parallel causing contention • Now critical systems structures recovered 1st and other structures optionally prioritized by policy • zAware – Analytics – Detects anomalies avoid outages • MQ ShrQ CF full avoidance – • EC12 Storage Class Memory (SCM) (AKA- Flash Memory) • May hurt performance as slower than CF memory

  33. Questions

  34. SHARE Sessions with more details • 15841: EWCP: Project Open and IBM ATS Hot Topics • Monday, August 4, 2014: 1:30 PM-2:30 PM Room 303 • Speakers: Kathy Walsh(IBM Corporation) • 15806: IBM zEnterprise EC12 and BC12 Update • Tuesday, August 5, 2014: 10:00 AM-11:00 AM Room 310 • Speaker: Harv Emery(IBM Corporation) • 15105: z/OS Parallel Sysplex z/OS 2.1 Update (Annaheim) • https://share.confex.com/share/122/webprogram/Session15105.html • 14142: Unclog Your Systems with z/OS 2.1 – Something New and Exciting for Catalog (VSAM RLS UCATs) (Boston) • http://proceedings.share.org/conference/abstract.cfm?abstract_id=26822

  35. 谢谢

  36. Backup Slides

  37. z/OS 1.12 – Servers w/ no active enclaves • Controlled by new IEAOPT Parameter • ManageNonEnclaveWork= {No |Yes} • No: (default) Non enclave work is managed based on the most important enclave. • Doesn’t work well when no active enclaves and other work to do • Example; Significant work unrelated to an enclave: • Garbage collection for a JVM (WAS) • Yes: (new / recommended) Non-enclave work is managed towards the goals of the address space external service class • Enclave managed address spaces service class goals / importance is more important than it used to be. • Verify high enough before switching to Yes

  38. SMF70 - Warning-Track-Interrupt Metrics Metric of interest % WTI Successful = SMF70WTS / (SMF70WTS + SMF70WTU) CMF PTFs BQM0868 (5.8) or BQM0867 (5.9) RMF APAR OA37803

  39. SMF 42 – SMSVSAM - VSAM RLS • Subtype 15: Storage Class Response Time Summary • Subtype 16: Dataset Response Time Summary • Only generated if DSN Monitoring is enabled • using the V SMS,MONDS command • Remembered by SMSplex, not available via Parm • Subtype 17: Coupling Facility Lock Structure Usage • Subtype 18: CF Cache Partition Usage • Subtype 19: Local Buffer Manager LRU Statistics

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