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While benchmarking the disk on a Windows XP VM under XenServer 5.6 I get a peak for a couple of seconds to ~200 MB/s before it drops back to an average of 30 MB/s. Is this normal?

My configuration is: HP blade server BL460 with 1 quad-core Intel Xeon processor (2.66GHz), 24 GBs of ram, and two 300GB 10K SAS SFF hard drives forming a RAID 1 array. My dom0 has 10 XP VMs and 2 Windows 2003 R2 VMs.

I that realize I'm going to get slow results using a RAID 1 array with 2 drives, which is why later on tonight I'm upgrading it to a RAID 10 with 4 drives and hope for much better results. Is that a reasonable hope?

I've already followed every bit of advice there is about VM performance improvement, for example: disabling task and checksum offload.

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up vote 2 down vote accepted

I'm more of a vmware person than a xen, however those first few seconds are likely data being cached in ram at the hypervisor or storage controller.

30 MBps sounds about right for your throughput assuming one VM is generating most of the load.

Upgrading from raid 1 to 10 should provide a significant performance boost. Look at the raid level definitions for the kinds of gains to expect.

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thanks thats a relief! – 3a2roub Mar 3 '12 at 23:09
The reason for all linux based VM-solutions (I know of XEN) is this caching. – Nils Mar 4 '12 at 21:11

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