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
This is a follow on to a previous blog on " PowerVM Virtual Ethernet Speed is often confused with VIOS, SEA IVE/HEA speed "- here is a Direct Link I regularly get asked : "I have just heard about this [PowerVM virtual switch | vSwitch | Hypervisor Ethernet Switch] is available but I can't find out any information at all, help!" They are wanting to run two (or more) virtual switches within the one Power machine to completely separate the network packets of groups of virtual machines (LPARs) so they know for sure there can... [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]
The title should read "Local, Near & Far ..." - I will not correct it or links might fail. In this entry we carry on from part 5 but we are going to look at setting the virtual processor number for the virtual machine . There is a side effect that is not obvious and after 6 years of using them, it never occurred to me so perhaps it is news to others too. The problem of virtual processors is that they are ephemeral - i.e. they don't actually exist and costs nothing. So I find most systems administrators feel they can be generous... [More]
We all tend to concentrate on the CPU first and the memory second. CPUs, as the "brains" of the machine, does get a high focus and have a lot of extreme technology within it but the RAM is the "guts" of the machine to "feed" the CPU with nutrient data. OK, let us stop the analogy there :-) Along with reducing the number of CPUs via a lower virtual processor count, we also need to have the CPUs matching the memory - so AIX has a fighting change to localise a running process to its home SRAD and thus have it's data... [More]
After you have started and used your virtual machine (VM) for a while, you may decide to change its size using a Dynamic LPAR (DLPAR) change from the HMC (or SDMC or IVM, of course). This has virtual machine placement implications. When shrinking your VM, the hypervisor will decide which CPU or memory (LBM) to release and it might not select what you think is the obvious choice. When enlarging your VM, we might thing there is an obvious way to grow in a balanced way but we can't see: 1) where physically our virtual machine is placed in the... [More]
The Hypervisor makes the virtual machine (LPAR) placement decisions and changes during DLPAR. The Hypervisor is part of the Power Systems Firmware. The POWER7 machines first arrived in the early months of 2010. Since then we have had a lot of field experience with the larger machines with large configurations with large applications and tens of thousands of processes running and in particularly the machines with all three layers of memory - which are the Power 770, Power 780 and Power 795. From this experience, the POWER developers have... [More]
Finally, I have the types of memory by POWER7 model double checked. I refreshed the table in part 1 but thought I should make sure every one sees the final version so I have not mislead people. Only the Power 770/780 and Power 797 have Near memory. All the smaller machine operate a Local memory meaning on the same same POWER7 chip and Far memory for any access to another POWER7 chip's memory.
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]
The officials words I was sent: Starting on November 13, 2011, each IBM client accessing Fix Central (whether through their employees or other authorized representatives) will require an individual IBM ID to download fixes for a limited number of additional product areas (including AIX and VIOS). This requirement will be expanded to additional products in the future.This requirement will be expanded to additional products in the future. The registration process will be quick and simple and will provide users with a customized experience to... [More]
Active Memory Deduplication was announcement on 12th October and available on 14th October but there has been a little confusion on: what you need, how you install it and run it and how it works? This blog will attempt to demystify this interesting new Power Systems feature. This is one of many features to reduce the memory foot print and so reduce costs for POWER and AIX logical partitions. So far we have: Workload Partitions - reduce the memory used by many copies of AIX to just one Global copy and applications installed at the Global... [More]
I have been using Shared Storage Pools phase 2 (SSP2) on the beta test a lot recently and it works well - I am very impressed. One key side effect of SSP2 is that it really makes Live Partition Mobility (LPM) very simple and safe. But then I hit a problem that stumped me - nothing to do with the SSP2 technology - it was just that I in the Advanced Technical Support group have got rusty in setting up and using LPM. The first problem that most people hit is that the source and target Power machines must have the same LMB size - the what??... [More]
I just realised that I got help from the AIX developers to explain the output of the mpstat -d command for my POWER7 and Affinity Technical University sessions in Miami and Copenhagen that I never passed on to every one. In an earlier blog we examined some mpstat columns but skipped others. The nearly undocumented mpstat stats are: S0rd, S1rd, S2rd, S3rd, S4rdand S5rd. In the AIX manuals it states: S0rd = The percentage of thread re-dispatches
within the scheduling affinity domain 0.
And likewise for the other numbers - but what does... [More]
Below is from your Power Systems, Advanced Technical Support team in Europe (EMEA) with lots of input from many people.
We find many people are over optimistic and making assumptions - which can catch them out - we learnt the hard way too.
Don't Assume 1 - The same boost as last time
It may be that you migrated from 2Mit to 10Mbit and saw approximately a 5 fold increase in performance.
Similarly when you went from 10Mbit to 100Mbit, and from 100Mbit to 1Gbit; you saw... [More]
At the Miami and Copenhagen Power Systems Technical Universities, I covered what we knew about the next release of Systems Director (6.3) planned for 16th December 2011. One of the hot topics was High Availability using disk replication for the embedded DB2 database for active:passive fail-over. It turns out this feature is not included with Systems Director 6.3 release - sorry about that. The good news, at least, is that this feature is in development and working for the next release of SDMC, which is based on Systems Director 6.3... [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]