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 typical request from IBMers in services or direct from customers wanting to confirm a good disk setup or confirm disks deliver as promised. This time "... a test of SAN disk performance where LUN's are carved from a IBM Flash System 820 with SVC. Primary objective is to show the IBM Flash System 820 can do hundreds of thousands IOPS with response time <1ms with good throughput. This is for an Oracle RDBMS using ASM"
Wow!! those new Flash Systems are really the next generation of disks. Well disk testing is not... [More]
In Advanced Technology Support (ATS), we like to think we know what we are doing. Then something catches us out and we think that we had better let every other Power Systems administrators know about this or there are going to be many horrified users out there and many complaints. Note this problem hit our combination of HMC, VIOS and machines - you might get lucky but don't risk it!
Gareth Coates (my ATS partner) volunteered to perform the regular 6 month update of our systems but hit a BIG problem. He writes:... [More]
I have been looking at some nmon data from an IBMer looking into a customers machine. The virtual machine (LPAR) is running the Oracle RDBMS with 75 dedicated CPUs - on a POWER7 Power 795 at 4 GHz.
The Excel spreadsheet is quite scary at 144 MB thank goodness my Thinkpad has a SSD but not the record by a long way. Too many data save points can ready add u and so too can lots of processes if you are saving process data. Also with 75 CPU and SMT=4 that is 300 Tabs for Logical CPU, 300 for PCPU and 300 for SCPU and that... [More]
A very nice chart from Richard Milton of IBM on the minimum levels for AIX and VIOS of Power7 and Power7+ hardware.
Download as a PDF: AIX_Levels_on_POWER7_Hardware_2013_06_20.pdf
We will try to update this as new machines arrive.
I got asked these questions recently and had to go look the subject up ... again! I seem to have forgotten some of the details and then I thought I would use some new features of AIX for the second part. In the distant past there was various way to stop core files being dumped in to the current working directory of the program that failed. In AIX 5.3, AIX 6 and 7, the "chcore" command does all the hard work for us by letting us
Choose a specific directory for core files - which is best in it own filesystem so it... [More]
Following on from my previous AIXpert blog on 1st July 2013 - "Core files filling important filesystems? Want email alerts about each core dump?" it was pointed out to me by AIX guru Mathew Accapadi that we can for many years use the ODM and AIX error reporting framework to send emails on the generation of core files. See the previous blog on how to force the core files to a particular directory - and not allow them to fill up important system directories. On the alternative reporting method see below:
Check out the... [More]
I have tried to get permission to pass on these numbers publically but got no answer at all. As these are facts rather than opinions, I see no harm in them. So I will work on the old theory: "it is easier to ask for forgiveness than permission" ... here goes.
The AIX Virtual User Group often asks a few questions as part of the registration process for the next webinar session and it generates fascinating statistics from real POWER and AIX users.
The people that join the AIX Virtual User Group are... [More]
The fifth POWER Ask the Experts is a one day customer technical event in the UK which ran in Manchester and London on 15th/16th July 2013. It proved to be a very popular free event. We had well over a 100 people attend which was a mixture of customers, a few Business partners and some IBMers.
10:00 - Power Systems Update - Pat O'Rourke: Austin Briefing Centre, USA Download 22MB .pdf
11:15 - Performance Best Practices with POWER7 - Nigel Griffiths, ATS Europe ... [More]
When you install Linux on an IBM POWER processor machine (Red Hat, SUSE or now includes Fedora), you then need to add the IBM supplied additional RPM packages. These give you a whole bunch of useful tools like HMC comms so you can Dynamic LPAR change and LPM, diagnostic tools, and configuration listing commands. Plus more importantly nmon :-) The repository allows you to update your packages as new versions become available and to benefit from fixes and additional functions. Without these you don't get the full Power... [More]
The answer is "it depends" and there is no Rule Of Thumb - IMHO.
The 2 times ROT is very old school and for small servers where peaks could really run out of RAM fast and hurt.
The worst I saw was 6 times but that was OS guys and RDBMS guys and app guys all said 2 times ... each!! and then the System Admin guy just added them up not realising it was the same 2 times! Basically, bonkers and they used 2% in the end.
With machines with large memory, say starting at 64 GB, the memory demand... [More]
I regularly get asked a question like: I have 4 months of data from 25 machines and have to develop a Capacity Planning model to size these LPARs on to new machines but I am having problems with having so much data. What can you recommend? We need graphs of
CPU compared to Entitlement
CPU Physical CPU use
Maximum real memory use
Sometimes this data is needed as input in to the Workload Estimator tool or Server Consolidation tools.
I had better point out that any performance tool of AXI command in a POWER Virtual Machine (LPAR) can only see its use of the Physical CPU, the size of its own CPU pool and (if Monitoring is switched on at the HMC), it has a number of the CPU use by "Other LPARs" use of its own CPU Pool. nmon gets these numbers by default and the nmon analyser graphs this data in the LPAR tab - this assumes its a Shared CPU LPAR. If it is a dedicated CPU LPAR then it can't get any of this Pool data and there is no LPAR tab in the nmon... [More]
When I log on to my home machine being AIX,of course, and type hostname I get:
nag@blue:/home/nag$ hostname -s
I get this because when I set the hostname in smitty it looks like this:
* HOSTNAME [ blue.aixncc.uk.ibm.com ]
* Internet ADDRESS (dotted decimal) [126.96.36.199]
Network MASK (dotted decimal) ... [More]
Most AIX system administrators use: smitty tcpip to add a hostname, IP address, network mask, gateway and DNS server setting to get the virtual machines (LPAR) and AIX on a network. And as a side benefit so we don't need to use the ghastly VTERM console any more as ssh or the dreaded unsecure telnet (just don't do it) can now be used - as the root user:
# smitty tcpip
Minimum Configuration & Startup
Use DHCP for TCPIP Configuration & Startup