Category Archives: block devices

Online Enabling new DASD from a Linux LPAR on System z

When running a mainframe, there are reasons why you you want to add new control units and DASD disk devices. Assuming that you already added the hardware configuration to the system, you will find that a still running LPAR with … Continue reading

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DRBD and Network Restarts

Using drbd as a simple and reliable alternative to distributed block devices is quite common. Especially in primary/primary mode, it provides the possibility to host block devices for virtual machines on two different hosts. However, there is one annoyance that … Continue reading

Posted in block devices, DRBD, Networking | Tagged | 1 Comment

Xen or KVM

Since little more than half a year, I am in the process of installing a new virtualization Platform. One of the hardest decisions to make was if we should use Xen or go with KVM. We already have Xen in … Continue reading

Posted in block devices, KVM, Networking, openSUSE, Xen | 1 Comment

Simple udev Manipulations

When discovering the /sys file system, one can find quite a number of tunables that look interesting and really have effect on system behavior. Especially when experimenting with different values of read ahead for block devices or e.g. setting the … Continue reading

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Checking Block IO in Linux

For many workloads, performance in current systems is most often limited by IO. Be it memory IO as looked at in Linux and Memory or be it file system IO. The file system strongly depends on the underlying block device(s). … Continue reading

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