November 25, 2013

Installation of Linux on System z

Now and then I get the question on documentation for the base installation of Linux on System z. As this depends on the distribution, take a look at the documentation from the distribution partners first:
There is also a Live Virtual Class with a demonstration of some of the access methods. Charts and a replay are available for this.
The installation is also covered in several Redbooks, e.g. The Virtualization Cookbook for z/VM 6.3, RHEL 6.4 and SLES 11 SP3. 

November 22, 2013

Red Hat Enterprise Linux 6.5 released

Nine months after the last release Red Hat has announced the availability of RHEL 6.5. The kernel level is now kernel-2.6.32-431.el6, for the main bug fixes see the kernel update description.

As usual there are the release notes and the technical notes in two separate documents. For System z this has been a mainly a fix release. Only a few small enhancements have been added all described in the technical notes. Here are some of them:
The IBM documentation for RHEL 6.4 on developerworks still applies for this release.

November 18, 2013

Raw ECKD access from zLinux

Since a while the Linux DASD driver has been enhanced to access full ECKD tracks. Basically the following steps are needed:
  1. Take the device offline from other System z operating systems
  2. get the device online in zLinux 
  3. switch the device in raw ECKD mode:
    echo 1 > /sys/bus/ccw/devices/<device ID>/raw_track_access
  4. use a program that reads and writes whole tracks (64k) with direct IO like a dd with the respective flags to read or write
More details can be found in the chapter about the DASD driver (search for "raw_track_access") in the "Device Drivers, Features, and Commands" book for the respective distributions, e.g.
This book is really recommended as a reference.