XenServer and bad IO performance under Dell

An update on XenServer and the bad IO-Performance (hard-disk performance) under Dell servers. We had a blast over here…So, what to do with virtualisation? Basically, you have some options:

  • Xen. Like in Debilian. Works as a charm, but can be hard to configure;
  • Microsoft Virtualisation. Thanks, but not thanks
  • KVM. No opinion yet
  • VMWare. We had ESXi working but it did kick ass (mine) when the host decided not to delete logfiles. Solution? Migrate everything away from the VMWare host, and retry. Thanks a lot
  • Citrix XenServer. Still suboptimal, but does a job…

So, we have a XenServer running with some Linux and Windows hosts. Works reasonable, except for IO. The Windows XP host – optimized – gave a whopping 2 mb/s.

Then, a customer wants to use our system. We would like to, but first, we’ll copy the current VM’s to a new server. We got a new server from Dell, a new R210, with SAS in RAID-1, 8 GB of memory and more good jazz. The TAM (Technical Account Manager) of Dell guaranteed us that the performance of this machine must be sufficient.

It gave a whopping 2 mb/s

Talking to my old accountmanager I mentioned this. He asked Jeffrey Beekman from Dell to join the conversation.

Jeffrey told me that he had this before. It seems that the Dell Perc-i and H200 cards of Dell have caching, but IT IS NOT ENABLED BY DEFAULT. Even better: to enable it, you must install Dell OpenManage on the server.

We did so, and had a reasonable performance after installation and switching the caching on. To do so:

  • Assuming you have a working – up to date – XenServer. We used 5.6.1FP1;
  • Download the OpenManage for Linux pack… No, even better, download the OpenManage for XenServer pack. Burn the ISO
  • Pop the CD in the XenServer, open up the console;
  • mount /dev/cdrom /mnt
  • cd /mnt
  • ./install.sh
  • Reboot the whole server
  • From your browser, kick in the OpenManage webinterface with httpS://<yourxenserver>:1311. Username root, password $password
  • Go to storage, open up your Virtual Disk, change the policy of the Virtual Disk, and make sure that your caching is enabled. I did reboot here;
  • Enjoy!

Kudu’s to Jeffrey Beekman of Dell.

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