December 15, 2011

Gathering performance data with sysstat

The sysstat package is included in all distributions but not always installed by default. It's a collection of performance monitoring tools and you can check the options for your current version in the manual pages. It's platform independent and so this works on Linux in general.

After installation of the package there are two different ways to gather data.

Using the command line
Ad hoc data can be gathered by calling the data collector from the command line. For newer versions of sysstat the command

/usr/lib64/sa/sadc -S XALL -F 5

and for older versions of sysstat the command

/usr/lib64/sa/sadc -d -F 5

will collect data in 5 second intervals until it's interrupted by ^C. The -F forces a file compatible with the current sysstat version and the -S DISK or -d enables the collection of statistics for the block devices.
You then can convert the created binary file by

sar -A -f > outfile.txt

to get a report to read. There are many options for sar to select what's being shown in the report, please check the man page for them. The -A option shows all the data.

Using cron
For regular monitoring the distributions configure sysstat to be started as a cron job or as a service. The history files are then put under /var/log/sa and converted once a day to text file. In the configuration file /etc/sysstat/sysstat (SUSE) and /etc/sysconfig/sysstat (Red Hat) the archive settings for this history can be configured.

For SLES  you can install the cron settings by
  • SLES10: /etc/init.d/sysstat start
  • SLES11: /etc/init.d/boot.sysstat start
  • SLES12: systemctl start sysstat 
For RHEL5, RHEL6, RHEL7 the installation is done automatically.

For Ububtu 16.04.1 cron jobs are disabled by default (after installation). You have to edit the file /etc/default/sysstat and change the variable ENABLED from "false" to "true". After that you have to restart the service: /etc/init.d/sysstat restart

In the end there is a file/link to /etc/cron.d/ that you can adapt and e.g. changing the 10 min collection interval or adapting the reports (e.g. add the -S XALL). As usual the documentation for the sa1 and sa2 commands used there are in the respective man pages.

(updated 10/12/2016)

December 13, 2011

New whitepaper: "Sharing A WebSphere Application Server V8 Installation Among Many Linux for IBM System z Servers"

In the new white paper "Sharing A WebSphere Application Server V8 Installation Among Many Linux for IBM System z Servers" you find a hands on description on a more complex WAS server setup. This is the update of the white paper covering WebSphere Application Server V7.
So if you want to install once and use the installation in many Linux guests take a look at this.

New Redpaper: "Installing Oracle 11gR2 RAC on Linux on System z"

This Redpaper describes the installation of the latest Oracle DB on RHEL 5 and SLES 11 for Linux on System z. It covers both ECKD as well as SCSI installations and on the Oracle side the Grid Infrastructure and RAC.
It's a good documentation that you should read before you starting the installation!

December 5, 2011

z/VM 6.2 - beyond SSI and LGR

The main features in z/VM 6.2 are certainly Single System Image (SSI) and Live Guest Relocation (LGR). With that it's now possible to have up to four z/VMs in one cluster and move the Linux guests from one to the other. So finally a z/VM update will no longer require a Linux outage. IBM generated lot's of technical and marketing material about this. 

However there are performance enhancements in z/VM 6.2 as well that will help running Linux guests that should not be neglected. See the links below for more details:
  • many memory management improvements, that are all transparent to the Linux guests. So install them and if you've been running in memory over committed scenarios with Linux, you'll get the performance benefit.
  • additional performance enhancements, some of which have been also available as APARs on older z/VM releases.
So it's definitely worthwhile to update older versions to z/VM 6.2 just because of those enhancements. On top there are also several really useful technology exploitations available.

December 1, 2011

How to find software solutions for Linux on System z

There are multiple sources for finding middleware and solutions for Linux. As the web sites get updated this may change - let me know then I adapt the description.
Please note that none of those catalogs is complete, they are all snapshots. 

IBM Global Solution Directory (GSD)
Here you can create complex searches. To select Linux on System z select "IBM System z (Mainframe)" under platform configurations and then all the operating systems you are interested in. Finally click on "search" without entering anything else.
IBM Software (SWG) product compatibility
The most important reports are the operating system reports. When generating searches please be aware that their are two different entries for RHEL. The base one has RHEL2 - RHEL5 whereas the one titled RHEL server has RHEL6.
SUSE Enterprise Linux server is all under SLES.

IBM System z page (unfortunately discontinued by IBM end of 2013)
This page lists the ISV solutions updated in approximately the last year.

Red Hat Product Catalog
All the products registered with Red Hat. After you've searched for a specific product you can check the platform and see where it's running.
Note that Red Hat is still using the search term "zSeries" for referring to "System z". So you may want to try this search term as well.

SUSE Linux Enterprise Software Catalog
SUSE has a catalog that can be searched quite easily. Click on "advanced search" and select "IBM System z" as the platform and you get all the vendors offering products for the mainframe that registered with SUSE.