AIXpert Blog is about the AIX operating system from IBM running on POWER based machines called Power Systems and software related to it like IBM Systems Director, PowerVM for virtualisation and PowerSC for security plus performance monitoring and nmon
Update: The developers and the manuals call this Load Sharing but most people think it is called Load Balancing. Perhaps, balancing gives the wrong impression of fine grain packet by packet balancing where we actually have higher level, cruder splitting of the work with Sharing. Below I use the word Balancing but mean Sharing. I have got a few questions recently on how to set this up as there are announcement with near zero information on setup, the configuration needed and a worked example. So here goes. For a long time now we have had SEA... [More]
Before we look further in to memory affinity we need to recap on the scheduling of processes and process threads of a multi-threaded process to simultaneous multi-threading (SMT) processors like POWER7. POWER5 and POWER6 had two modes of SMT off (one thread) and on (two threads) - with SMT=on two processes run at the same time (in the same clock cycle) on the CPU-core but using the different logical units inside of the CPU-core (units like the integer maths (there is more than one), floating point maths (there is more than one), compare and... [More]
I am preparing sessions for a POWER/AIX Technical Conference in Norway - unfortunately the only place they could book for the event was a Ski Resort up in the mountains and there is still good snow. It is a tough gig but someone has to do it :-) As part of that conference, I am updating them on Systems Director and demonstrating it. I had a slide with these hints and tips. A slide with zero percent marks for style (far to many words and just a long list) and I thought ... I should share these with everyone, so here they are. Most of these are... [More]
This mysterious AIX CPU Folding area is often misunderstood, so below is what I know from osmosis from talking to various guru level developers over the last 10 years. Shared Processor virtual machines (LPARs for the old fashioned) have a setting called Virtual Processors (or VP for short). This is the number of physical CPUs that the virtual machines can spread out across - in fact, I prefer to call it the "spreading factor" as it is much more obvious what it means. This can be the upper threshold for the number of CPUs that can be... [More]
The title should read "Local, Near & Far ..." - I will not correct it or links might fail. With a shared processor virtual machine (I am calling this "VM" but was called LPAR!) there are various suggestions of setting Entitlement ("Desired processing units" on the LPAR profile on the HMC, I am calling this "E") and Virtual Processor numbers (I am calling this "VP"). For Capped, the Entitlement is the maximum guaranteed CPU time that you can't go over and you round up the Entitlement to the... [More]
I have had a couple of Power systems administrators make assumptions about the virtual Ethernet speed improvements when they install a 10 Gb IVE/HEA in a VIOS which are simply not true. I guess that if three teams have made this mistake then others are about too. So I intend here to put the record straight. The expectation is that (deliberately fully spelt out long-hand to make it very clear): When they upgrade the Integrated Virtual Ethernet (also called a Host Ethernet Adapter) from 1 Gigabit per second to 10 Gigabit per second that the... [More]
Just completed the move of the POWER and AIX Hands-on Movies to YouTube videos - after pruning we have 97 of them. This means you can watch them on your mobile Smartphone and Tablets in addition to your workstation/personal computer. You can find them all here:
YouTube look for my "Nigel Griffiths" Channel http://www.youtube.com/user/nigelargriffiths This should mean they are simpler to find, search for and view. During the transfer I pruned out a few of the older ones particular Systems 6.2 as we now have a set of Systems... [More]
I thought I should summarise the long eleven part Local, Near & Far POWER7 Affinity series. 1) Placement: Find out the layout of your boxes CPU and RAM and if the RAM is evenly distributed across available DIMMs Find out the placement of your Virtual Machines (LPARs) with lssrad -av - or - topas -M 2) SMT4 : Expect POWER7 SMT4 CPU use to “look” different POWER5 & 6 have two equal threads POWER7 shuts down threads 3 & 4 and even thread 2 - when there is not enough processes running. 3) Entitlement : Only set minimum Entitlements,... [More]
I have been wondering why the lower end POWER7 machines have local and far memory and not local and near. Perhaps you wondered too! Well at the Miami Power Technical University, I got to talk to Dr Joel Tendler (IBMer) and a POWER7 processor guru and put the question to him. He covered this sort of architectural topic in his presentation at the event and I learnt a lot in this area by listening to the "master". Below is some background and the explanation too. The POWER7 chips has two memory controllers for maximum performance but... [More]
N-Port Id Virtualisation (NPIV) and virtual Fibre Channel adapters - like high speed physical adapters (see an earlier blog) do require memory to operator at full speed. NPIV effectively turns the Virtual I/O Server (VIOS) into a kind of virtual SAN switch where packets are passed through with no changes from the physical adapter to the client Virtual Machine (LPAR). I found it very hard to find a recommendation in the documentation but was given a rule of thumb. As before it should be noted that starving the VIOS and the Hypervisor of... [More]
I was just asked this question by customer and it got me thinking, Items I would include: WPAR takes seconds to create and LPARs minutes LPARs need setting VIOS LV or LUNs but WPARs add simpler NFS mount points, or can just use Global AIX diskspace options LPAR needs 512 to 1GB to boot AIX and a WPAR takes just ~60 MB (yes sixty megabytes) You can share application code say 1 GB in each and every LPAR (40 LPAR = 40 GB) or just one shared read-only copy for all WPARs 40 WPAR = 1 GB).This saves man-power in maintenance, disk space AND memory (if... [More]
POWER Relative Performance (rPerf) is often used as a way to approximate the expected difference in performance between two Power Systems servers. Although rPerf is a useful tool, it is important to understand the limitations of using rPerf to provide an estimate the performance of your specific workloads in your particular environment with a new server, First, rPerf numbers, like any published benchmark, represent the best case result when the application, configuration and system resources are all optimized -- factors that are likely not... [More]
Common question: I see XX% of Used Memory but I don't know who is using it and how?
A simple question but there is no simple answer as memory use if complex.
nmon then hit "m" will quickly show you a few big uses of memory as below:
The shared memory used by lots of applications like DB2 and Oracle - check the SEGSZ for the size.
The Owner column usually tells you what it is used for like the oracle user for the SGA or db2inst1 for the DB2 buffer... [More]
It has bee a long few weeks traveling to Dublin, Las Vegas, Slovenia, Germany and Sweden to give lots of presentations. Six Weeks and five countries and the expenses are piling up on my desk. I was presenting a core set of topics like POWER7+ announcement summary, VIOS Shared Storage Pools (SSP3), Workload Partitions (WPAR) and Versioned WPARs to run AIX 5.2 and AIX 5.3, quick introduction to PowerSC (security tools), a Techie "what you need to know about" Systems Director for AIX, and Quick Dips in to Active Memory Deduplication... [More]
Earlier today I received email from a customer reporting their large POWER7 based machines where on firmware 720_64 to 720_90 and their reluctance to take the outage to upgrade it. They were asking for fine details of newer firmware levels and what advantages this would bring to " justify the outage to their user departments ". To be blunt this is a horror story: I lay awake at night in a cold sweat about stories like this. The customer has the whole "running computers plan upside down". The question should be " can... [More]