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
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]
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]
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]
This is a follow on from yesterdays blog due to Chris Gibson highlighting a question/concern from one of his customers in Australia.They were comparing Power6 and Power7 and the utilisation numbers from the SMT Logical Processors and the graphs look different. I looked at some nmon data (what else!) and yes they are looking different and then I ran a simple generated workload test and duplicated the graphs. Below I then explain them - once again these are my personal observations rather than an official AIX developers insider statement. I... [More]
I am working with a larger Power 7 customer and learning lots about life in the large and professional computer room. Oh Gosh!!! My Power Virtual Machine (Logical Partition) is totally busy. Oh Heck!!! Look at all that System time, we have a serious problem!! Or do we? Take a look at the below nmon stats and make up your own mind before scrolling down. Actually, we are in offices many miles away from most of the Power 7 computers because the machines are
split across three sites. More than twenty Power 7 Model 795's is
enough to... [More]
We have all probably seen or used the topas CEC on-screen view (topas -C command). This is started while logged into one AIX Virtual Server (LPAR) and shows all the other AIX or VIOS (as it is based on AIX) Virtual Servers of a single Power Server. Here is a reminder - this is on-line, on-screen and updated every 10 seconds or so: Here my Virtual Servers are called purple<something> and below the top machine summary we have a line for each Virtual Server and stats like AIX release, memory use, CPU stats (PhysB is the Physical CPU time... [More]
If you are migrating work from an older POWER5 or POWER6 machine/LPAR to POWER7 ... don't forget to check that those Java versions are compatible with POWER7 or you may hit "unexpected Java errors" The approved Java SDK on POWER7 are limited to particular versions with specific fixes . They can be found here: http://www.ibm.com/developerworks/java/jdk/power7/index.html Harder to check are the Java versions which are embedded in applications. Here are two important ones for IBM software: There is a technical bulletin regarding... [More]
If you are looking for an update on AIX on the IBM BladeCenter blades or looking for the details of the latest POWER7 based blades, there is only one place you need to remember. I am adding this to this blog because I couldn't find it and you might have the same problem :-) Its here - Power Blades Wiki Look in the Presentation list for the latest POWER7 blades PS700, PS701 and PS702 and AIX levels its supports presentation. This is by the world wide "top gun" of Power Blades Trina Bunting. Lots on informative pictures, the extra card... [More]
Questions I have a number of customers asking me these types question:
Are there are good practices on how to size disks for the storage pools. If I want a 5 TB pool, how many disks which size, does it matter ? Also are there any document limits regarding, pool disk, LUN and so on. Answers Not sure about best practice but there is common sense - will that do? Restrictions are included with the VIOS announcement "Read Me" notes, which you can find here for the current VIOS 126.96.36.199... [More]