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
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]
Stephen Atkins (the Guru behind the nmon Analyser) has released a new version - two days ago. This includes loads of improvements and some new features. Best of all - less problems running on newer Excel releases (it works around inconsistencies with the Microsoft API). I have always said that at least 50% of the popularity of my nmon is down to the excellent Analyser graphs. Very few people regularly see the online screen view. Thanks again Steve, for all your many hours of hard work in your personal time on the behalf of the tens of... [More]
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]
No more ordering CDROMs or DVDs for AIX installation media and waiting days - Note: this also works for IBM i. Now you download the AIX install .iso image over the web and install from
there: Use the virtual DVD drive on your VIOS 2.1 and install directly
into a LPAR Mount the image & read the contents into your NIM Server If you are a Luddite then burn a DVD and put it in the Power machine Mounting a .iso image on AIX is still hard work On recent AIX 6 systems
use the loopmount command. On older AIX versions use this
method from... [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]
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]
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]
Probably the default method of accessing the console of an LPAR managed by an HMC is to use the HMC from WebSM, and then open a console window. What's wrong with this? 1. Cut and paste don't work well. 2. It is inherently insecure even when WebSM uses ssl The vterm is still passed over the network in clear text. Next option: Use the 'mkvterm' command after doing an ssh login to the hmc. 1. You get an ssl protected session. 2. It can be tough getting the parameters right. Undocumented command makes this easy: Use 'vtmenu' which prompts... [More]
It was my birthday on Saturday and by pure luck my Raspberry Pi was delivered the day before - what a great day "hacking" (in the old sense of the word). I have been waiting for a few months for this delivery - What a treat!! If you have not heard of this credit size computer before here is the back ground. The Problem In the UK, school information technology education has been pitifully reduced to Microsoft Word, Excel and Powerpoint. My own kids came home badly depressed as they started the classes as they knew far more than the... [More]
JFS2 buffers often needs to be tuned for I/O intensive applications. The performance gains can be large. Last month I was involved in a stress benchmark where JFS2 tuning improved batch performance by a factor of three. To determine if your AIX system needs JFS2 tuning, run the "vmstat -v" command several times over a period of 10-30 minutes during peak processing. If the number of "I/O's blocked with no fsbuf" increases with time, you need to increase JFS2 buffers. Increasing JFS2 buffers is straightforward. Simply increase the... [More]
I often get asked: How large to make a pair of Virtual I/O Server (VIOS)? The classic consultant answer is "it depends on what you are doing with Disk & Network I/O" is not very useful to the practical guy that has to size a machine including the VIOS nor the person defining the VIOS partition to install it! Observations : The VIOS server unfairly gets a bad press but note: Physical adapters are now in the VIOS, so device driver CPU cycles (normally hidden and roughly half of the OS CPU System time) move to the VIOS - this is not... [More]
A large UK customer is running a series of tests on AIX and POWER7 machines and wanted to display the results on a webserver using rrdtool and needed help getting a working example running. So I stepped up to the challenge one night rather than it becoming a search for rrdtool skills inside IBM - when I could sort something out in a few hours. No one in IBM would claim to be a rrdtool expert until they knew the details of what was required. Many people know it well enough to get what they want done but would not put rrdtool guru on their CV. ... [More]
The AIX "lru_file_repage" is a new and more flexible memory tuning option that solves the problem of having to limit JFS2 file cache to guarantee memory for applications like databases. It is available starting with AIX 5.2 ML5 and AIX 5.3 ML2. It can be set using the "vmo" command or via "smit tuning => Memory". Here's how it works. AIX classifies memory into two categories: file cache and working storage. Over time, memory use grows with both types of memory. AIX will eventually need to free memory, and it can do so by freeing either file... [More]