Monthly Archives: October 2014

Find and recover space used by deleted files, shown by df but not by du

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When you’re running low on space on a file system, that can cause various unexpected behavior of the system, depending on which file system is filling up. For me, when that happens, I usually first issue a disk free (df) to see which is the file system that is almost full. Once I know which file system, I go and search which files take up the most space in that file system and take action. Sometimes, df show that a file system is almost full while, when summing up all the space by all files doesn’t even come near that value.

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Install and use Debian Wheezy as Xen virtualization host

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Earlier, I explained how to setup CentOS or RHEL as a KVM virtualization host. You can find that  explanation here. It also contains some basic terminology about virtualization which is also applicable for Xen. When talking about KVM, somehow, I immediately associate it with the Red Hat family just as when you talk about Xen, I associate it to Debian derivatives. So for this post, I’ll use Debian to install a host that will run Xen-VM’s by using paravirtualization.

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Start with a simple 2-node OpenStack setup with KVM

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OpenStack is something that gets more and more in the picture and even if you’re only a little interested in the latest technologies, you must have heard from OpenStack here or there. But what is it exactly and more important, how does it work practically. The best way to figure that out is just to get going with it and try to install it and play around. Here you can find a brief explanation and a tutorial or waltrough to deploy a small OpenStack environment on top of CentOS 7 or RHEL 7.

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Read and write a CMS minidisk on a z/VM system from a user/guest running Linux

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When you’re managing a z/VM host running multiple Linux images, it can be interesting to have access to the data which resides on a CMS owned minidisk. Such type of minidisk is probably used to control the z/VM related configuration of the guest itself in some way. Also, when scripting, the explained technique can be used to read or write data from and to one of the minidisks. One example could be to change the PROFILE.EXEC from a user from within the user itself.

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Terse, unterse and transfer datasets between z/OS and other platforms via FTP

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Tersing files can be compared to tarring, zipping, rarring files on the x86 platform. It allows you to store a file or multiple files (members) in an archive. The archive is easily transferable and when the data is unpacked, it is guaranteed to be the same as the original source. Especially when transferring PDS’es and variable blocked (VB, VBS) datasets, this is important. Transferring normal datasets over FTP through other platforms from z/OS can be challenging an this article should provide some help.

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Execute queries on a Microsoft SQL server from the Linux CLI with ODBC and Kerberos authentication

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A while ago, the Windows-world and the Linux-world were not the best friends in communicating with each other. Especially not when it came to proprietary stuff like Microsoft SQL server. in contrast to everybody’s expectations, somewhere end 2011, beginning 2012, Microsoft released an ODBC driver for SQL server for Linux. This driver allows executing queries from a Linux machine to a Microsoft SQL Server database. The driver can be used in combination with Kerberos tickets and AD authentication to execute queries.

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