ESX Storage Journey Takes III

*updated 22Aug08 – an exciting find!  Do stayed tuned for ENCORE!
http://mradomski.wordpress.com/2008/01/19/benchmark-tools-part-i-disk-io/
In ESX Storage Journey Takes II, I mentioned about migrating one of our physical file server into ESX and attach a ISCSI storage drive to it.  And here it is, our long waited storage arrived a couple of weeks ago!  I’ve setup and run several test on this unit with a surprising find.

System Setup

Host
ESX 3.5 update 2, Dual Quadcore processor with 16Gb of ram.

Guest
Windows 2003 standard R2 Sp1
1 vcpu @ 2.5Ghz
1GB ram
Drive C is attached to EMC Clariion 3-20, 4GB cache with 5 x 10k 300Gb disks (FC@4gbps)
Drive D is attached to MD3000i, 512MB cache with 5 x 7.2k 1TB disks (iSCSI@1Gbps)

I’ve plug the MD3000i directly into the ESX installed Dell 2900 bypassing the switch to minimize possible bottlenecks.

Performance Test
I’ll be using Iozone v3.3 throughout this test.  Although there are forums which indicates fluctuating results at high CPU utilization, I’ve found mine to be consistent. Nevertheless, I’ll be conducting more test using other benchmarking software; that is if I find the time.

Testing speed of MD3000i connected to ESX Guest as RAW partition (Virtual).

Testing speed of MD3000i connected to ESX Guest as RAW partition (Physical).
Write speed is ridiculous here at 4MB/s.  I have to ran this report THRICE! to confirm my findings.
 

Testing speed of MD3000i connected to a physical machine (Windows)  *updated 21Aug08
The speed here is almost similar as if the box is connected to ESX as Physical LUN.

Charts of EMC 3-20(FC) versus MD3000i (iSCSI)
 
 
As seen here, MD3000i is really lagging behind in Random Write tests with a cap of 31MB/s versus somewhere 100MB/s for EMC Clariion.

 
 
Same here with results lagging bad behind EMC 3-20 box.

So what about the existing machine?  What is its current performance?

It is a Dell 2650. Storage is made up of 3 SCSI Raid 5 disk; specifications unknown as of now. Performance is as below.

Charts of Dell 2650 with 3 x disk on Raid 5

 
Performance over here is unexpectedly bad.  I’m starting to wonder if there are cobwebs in the spindles.  Having said that, I’ll definitely rerun this test again on my next post.

Conclusion
From the results I obtained so far, I just felt there might just be something amiss.  The 4MB/s write speed is so ridiculously slow, its comparable to a consumer class NFS device.

It is also good to note that once we’ve attached the RAW LUN into the guest of ESX in Virtual mode, we can see dramatic increase in the Writing Speed boosting it to 20MB/s.  I wonder if this is the result of additional caching done by ESX kernel.

Random Read speed is acceptable with peak times of 100Mb/s and average of 40Mb/s; keeping in mind 128Mb/s is the ceiling for 1Gbps.

Overall, I’m still not convinced on the capabilities on this unit.  The speed obtained is nowhere near my expectations on a enterprise classed storage device.  Although this product maybe classified as an entry level on the enterprise market, at the end of the day, I’m just not getting the performance I’m expecting for the price.

On my next post probably ESX Storage Journey Takes III – Encore, I’m going to plug the MD3000i directly into a physical machine running Windows.  Till then.