XenServer Creedence Alpha 3, Disk I/O testing (part 2)

We did some more testing of XenServer Creedence Alpha (XSCA3) disk performance, and plotted large streaming reads for a variety of record sizes against both a physical and Brand-X Hypervisor.

Recap:

• System is an AMD6176SE, 2 CPU, 192GB RAM 
• Local storage, 3x 10Krpm SATA, LSI 9261-8i, RAID0, thick provisioned 
• No special settings, tuning, or configuration 
• Testing is with dd and iozone, with and without Direct I/O (dd iflag=direct, iozone -I)
• CentOS 6 2 vCPU, 2GB vRAM (updated 3-07-2014) VM and physical 
• The system was idle 

Physical achieves ~600MB/s transfer speed. 
Brand-X achieves a similar figure.
XSCA3 achieves less than 50% of that, unless Direct I/O is used.
Neither physical nor Brand-X are significantly affected by use (or not) of Direct I/O.

Results for physical without Direct I/O are excluded as with 192GB RAM and only 8GB of test data, transfer rates are in the 2500-1700 MB/s range due to the abundance of RAM for cache. We took no steps to limit the physical CentOS to 2 cores either.
  
We know the disappointing XenServer performance is only for asynchronous (not Direct I/O) disk access, and that the system behaves as expected when running physical or Brand-X hypervisor. The mystery deepens!

Solaris vs RedHat vs Windows

Its been a while since our last Solaris/OpenSolaris post. Now, like buses, suddenly 2 come along at once. Both are related to performance, the first (this one) is about benchmarking Solaris versus other mainstream Operating Systems. The second will follow in a few days, and is about maximising Solaris performance when virtualized on XenServer.

Most people see Solaris as extremely reliable, but one misconception that many hold about Sun's OS is that it is slow. Unfortunately, few take the trouble to assess their choice of OS with an open mind, so Solaris remains a "well kept secret", known only to those who work regularly with all the major server Operating Systems.

One of our consultants has been doing some benchmarks for a client, and came up with results we published here.


Solaris x86 was almost always the best performer above Linux (RedHat), and Microsoft, on HP hardware. From 2 cores to 24 cores with a couple of exceptions, it outperformed the others on Geekbench, a CPU and Memory intensive benchmark.

Not a lot of people know that.