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Tips using HMC for VMWare Users

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 Creating a Virtual Machine is a necessary step of most of software development process. The reason is that we want to optimalise our hardware use, to isolate one application instance from another application  instance running in the same hardware. For that purpose I recently tried to create a VM instance in an IBM machine, a PowerVM. Creating such VM is quite different than creating such VM in VMWare, and this post will show some tips when facing challenges creating a PowerVM. HMC Console First, we need to access HMC (Hardware Management Console), which is the interface from where we configure our hardware and logical partitions. One HMC could manage more than one system (which stands for a single box of server hardware).  Choose Resource >> All Systems to get an overview of which systems are available to manage. From the HMC we could create a new Logical Partition. The menu path is : Resource >> All Systems >> [ choose system ], then by clicking on Cre...

The mystery of TCP segmentation offload bug

There are incidents that have a generic description 'TCP segmentation offload bug' that affects multiple virtualization platforms. The workaround is the same, by disabling this feature. Case one Virtualization Platform : KVM/QEMU Symptom : Periodically, guest would lose network connectivity after heavy load. Restarting the guest network doesn't fix the problem. Guest will be ok after rebooting. Reference : https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/997978/comments/134 Workaround :    ethtool -K eth0 tx off sg off tso off ufo off gso off gro off lro off Case two Virtualization Platform : Xen Symptom : DomU hangs after network heavy load (@10 Mbyte/s). Reference : https://bugs.launchpad.net/ubuntu/+source/qemu-kvm/+bug/997978/comments/132 Workaround : disable offloading using ethtool ethtool --offload gso off tso off sg off gro off Case three Virtualization Platform : VMWare Symptom : 1. Page could not be displayed after VM migr...