Planet Hypervisor

When Virtualised Storage is Faster than Bare Metal

An analysis of block size, inflight requests and outstanding data INTRODUCTION Back in August 2014 I went to the Xen Project Developer Summit in Chicago (IL) and presented a graph that caused a few faces to go "ahn?". The graph was meant to show how well XenServer 6.5 storage throughput could scale over several guests. For that, I compared 10 fio threads running in dom0 (mimicking 10 virtual disks) with 10 guests running 1 fio thread each. The result: the aggregate throughput of the virtual machines was actually higher. In XenServer 6.5 (used for those measurements), the storage traffic of 10 VMs corresponds to...

XenServer patches, the easy way, part 2

Patch all your XenServer hosts in one click. Period.

New ticket statuses on

I just wanted to mention that we've created a couple of new ticket statuses on, which should make it clearer where a ticket has got to in its lifecycle. Acknowledged Issue will be used when we've done initial triage on the issue, determined that it is a genuine problem, and made a ticket in our internal issue tracker for it. Previously we've varied between leaving these Open, and closing them as Done, but neither choice was very satisfactory, so we decided that a new status was needed. Even when an issue is acknowledged, there is no guarantee when it will be fixed; however,...

Xen Project now in OpenStack Nova Hypervisor Driver Quality Group B

A few weeks ago, we introduced the Xen Project – OpenStack CI Loop, which is testing Nova commits against the Xen Project Hypervisor and Libvirt. Xen Project community is pleased to announce that we have moved from Quality Group C to B, as we’ve made significant progress in the last few weeks and the Xen […]

Configuring XenApp to use two NVIDIA GRID engines

SUMMARY The configuration of a XenApp virtual machine (VM) hosted on XenServer that supports two concurrent graphics processing engines in passthrough mode is shown to work reliably and provide the opportunity to give more flexibility to a single XenApp VM rather than having to spread the access to the engines over two separate XenApp VMs. This in turn can provide more flexibility, save operating system licensing costs and ostensibly, could be extended to incorporate additional GPU engines. INTRODUCTION A XenApp virtual machine (VM) that supports two or more concurrent graphics processing units (GPUs) has a number of advantages over running separate VM instances,...

Xen Orchestra responsive design

You can use Xen Orchestra to administrate your XenServer even on a mobile phone or a small tablet.

Security bulletin covering VENOM

Last week a vulnerability in QEUM was reported with the marketing name of "VENOM", but which is more correctly known as CVE-2015-3456.  Citrix have released a security bulletin covering CVE-2015-3456 which has been updated to include hotfixes for XenServer 6.5, 6.5 SP1 and XenServer 6.2 SP1. Learning about new XenServer hotfixes When a hotfix is released for XenServer, it will be posted to the Citrix support web site. You can receive alerts from the support site by registering at and following the instructions there. You will need to create an account if you don't have one, but the account is completely free. Whenever a security...

A vhosting git setup with gitolite and gitweb

Since gitorious' shutdown I decided it was time to start hosting my own git repositories for my own little projects (although the company which took over gitorious has a Free software offering it seems that their hosted offering is based on the proprietary version, and in any case once bitten, twice shy and all that). After a bit of investigation I settled on using gitolite and gitweb. I did consider (and even had a vague preference for) cgit but it wasn't available in Wheezy (even backports, and the backport looked tricky) and I haven't upgraded my VPS yet. I may reconsider cgit this once I switch to Jessie. The only wrinkle was that...

Once again about pros/cons of Systemd and Upstart

Upstart advantages. 1. Upstart is simpler for porting on the systems other than Linux while systemd is very rigidly tied on Linux kernel opportunities.Adaptation of Upstart for work in Debian GNU/kFreeBSD and Debian GNU/Hurd looks quite real task that it is impossible to tell about systemd; 2. Upstart is more habitual for the Debian developers, […]

Hardening Hypervisors Against VENOM-Style Attacks

This is a guest blog post by Tamas K. Lengyel, a long-time open source enthusiast and Xen contributor. Tamas works as a Senior Security Researcher at Novetta, while finishing his PhD on the topic of malware analysis and virtualization security at the University of Connecticut. The recent disclosure of the VENOM bug affecting major open-source […]