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
- 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;
Kudu’s to Jeffrey Beekman of Dell.