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Dell PowerVault MD3200 and MD3220

Technically, the Dell PowerVault MD3000 series are really SAN systems, because they allow multiple hosts to connect(?), and it incorporates the RAID controllers. But Dell lists this in their Direct-Attach section. We should not get overly analytical on the designation. When the MD3000 first came out, I did not find anything in the documentation to say that it would support Windows Clustering. But the new models clearly do support Windows Clustering.

The PowerVault MD3200 and MD3220 with 6Gpbs SAS replaces the original MD3000 on 3Gbps SAS. The MD3200 series have four 6Gbps SAS ports per controller for host connectivity and one for expansion. Internally there is a 36-lane 6Gb/s SAS expander.

References (the links may change, so just search the full document name):
Dell PowerVault MD3200 and MD3220 Storage Arrays With Microsoft Windows Server Failover Clusters Hardware Installation and Troubleshooting Guide, the Dell Technical Guide Book
Dell PowerVault MD3200/MD3220 Series of Storage Arrays, the Dell Technical White Paper
Array Tuning Best Practices for PowerVault MD3220 and MD3200i Storage Arrays, (same paper with fancy formatting: Array Tuning Best Practices), the Dell Technical White Paper
High Performance Tier Implementation Guideline for PowerVault MD3220 and MD3200i Storage Arrays.

The MD3200 for 12 3.5in drives (and 2.5in drives with adapter) and the MD3220 for 24 2.5in drives are shown below.



The MD3200/MD3220 rear view is below.


MD3200/MD3220 expansion is shown below. The bottom unit is the MD32x0 and the upper two are MD12x0 expansion units.


MD3200 & MD3220 Architecture

Below is the MD32x0 controller architecture diagram from the Dell Technical Guide Book. I am presuming the Falcon IOC is an LSI controller, but could not find documents for this on the LSI website.


Pricing for the MD3220 with 24 73GB 15K drives ($329 ea) is $12,460 with single controller and $15,892 with dual controllers (+$3,432). All drives must be SAS, SATA devices are not supported. Presumably a SATA/SAS bridge is used. Below are Dell disk prices. The lower 50GB and 100GB capacity SSD are only for the PowerEdge servers, only the 149GB is supported in the MD3200.

15K 2.5in73GB$329146GB$439  
10K 2.5in146GB$259300GB$469600GB$1009
7200 2.5in160GB$239250GB$269500GB$319

The License Key for the Performance Tier is $3,660. The Dell test report shows that the performance option really boosts performance. I suppose it turns off the powerful cache, which really just gets in the way of actually doing disk IO.

The MD3200/3220 series can be expanded with the MD1200 or M1220 disk enclosures, in any combination with a maximum of 96 drives (MD3200 + 7 MD1200, MD3220 + 3 MD1220, and other combinations)

High Performance Tier

The High Performance Tier is described as "an optional upgrade that can increase the performance of MD3200 and MD3220 series arrays that have high drive count, Solid state drives (SSDs) or high data transfer workloads. This implementation is based on an enhanced firmware algorithm and does not require any new hardware dependencies."

Between you and me, I am inclined to think the enchanced firmware disables the cached IO that seems to cripple SAN performance, as in those really expensive SAN storage systems that the vendor sales rep told you was immensely powerful that would solve all your storage problems. Only when you got it, you found the performance was crap. In benchmarking world, it was known for a long time that caching disk IO had significant CPU overhead (where ever this caching was done) with negative impact on performance. Disabling and preferably bypassing cache code entirely improves performance to the level expected from the sum of the bare disk drives. So what exactly are these enhanced alogorithms?

The Dell High Performance Tier Implementation Guideline shows the following configuration for a performance test.

The host system (R710) has two dual-port SAS HBAs, the first HBA has ports S0 and S1, the second HBA has ports S2 and S3. The MD3220 has dual controllers C0 and C1.

The tests below employed 96 drives, 4 RAID 5 groups of 24 disks for sequential and 16 RAID 5 groups of 6 disks for random.