Although Dell acquired both EqualLogic and Compellent and continues to develop and innovate in those portfolios, the company’s native PowerVault storage line does not appear to have suffered for it.  In fact, Dell has continued to advance and expand the PowerVault line in some significant ways, as evidenced in the MD3200 series.

Unlike Dell’s EqualLogic and Compellent offerings, the PowerVault MD3260 series provides organizations with a direct-attached offering at a reasonable cost.  Although the MD series supports the use of SSDs, the MD3200 series is most certainly a capacity play, even though that SSD support does enable some additional performance-based opportunities.

In addition, Dell provides both “i”- and “f”-based editions of the MD series.  The i-based devices support iSCSI while the f-based devices support 8 GB fiber channel.   So, regardless of what kind of storage network you have in place right now, if you need capacity, one of the MD units will almost certainly fit your needs.

In this article, I’ll be looking at just the direct-attached storage part of the lineup.

MD3200

The MD3200, pictured below, is a 2U device that supports up to twelve 3.5” SAS, NL SAS and SSD drives.

The following types of drives are available:

• 15,000 RPM SAS: 300GB, 450GB and 600GB capacities
• 10,000 RPM SAS: 300GB, 600GB and 900GB capacities
• 7,200 RPM Near-line SAS capacities: 500GB, 1TB, 2TB and 3TB
• Solid State Drive (SSD) available – 200GB, 400GB (in 3.5” HDD carriers)

As you can see, there is very wide array of options, from massive capacity at relatively low cost to mid-speed 15K drives all the way to relatively low capacity SSD units that carry a higher price tag on a per dollar basis, but that do very well when the cost metric is dollar per IOPS.

MD3220

The MD3220 can support up to twenty-four (24) 2.5″ SAS, NL SAS and SSD in a 2U chassis.  The MD3220 is basically the same as the MD3200, but supports 2.5” drives instead of 3.5”.

Drives of the following types and capacities are supported in the MD3220:

• 15,000 RPM SAS: 146GB
• 10,000 RPM SAS: 146GB, 300GB, 600GB, 900GB
• 7,200 RPM Near-line SAS at 500GB
• Solid State Drive (SSD) available – 200GB, 400GB

Both the MD3200 and the MD3220 can be expanded with MD1220 and MD1220 enclosures to provide up to 120 hard drives in the base configuration and, with an optional license key, can be further expanded to 192 disks.  Bear in mind that this is very much a scale up architecture in that the MD32xx array holds the controllers and the connectivity ports.  The expansion arrays simply add more capacity to these base units, but do not provide additional

MD3260

The MD3260 is a 4U device that supports up to sixty 3.5” or 2.5” drives.  Yes, 60.  I first saw the MD3260 in person at the Dell booth at VMworld 2012 and was pretty impressed with the engineering that has gone into the device in order to cram 60 disks into 4U of space.  As you can see in the figure below, rather than sliding the drives into the front of the chassis, drives are installed in trays which lay flat.

With support for 3 TB disks, the MD3260 can support up to 180 TB in this 4U of space.

Drives of the following types and capacities are supported in the MD3220:

• 15,000 RPM SAS: 146GB, 300GB
• 10,000 RPM SAS: 146GB, 300GB, 600GB, 900GB
• 7,200 RPM Near-line SAS at 500GB, 1TB, 2TB, 3TB
• Solid State Drive (SSD) available – 200GB, 400GB

With the use of 3TB disks, you can deploy 180 TB of raw storage into a 4U chassis with the MD3260 and you can further expand this behemoth with MD3060e expansion chassis.

Shared SAS

These arrays can be shared between multiple servers using just SAS connectors.  There’s no need to deploy a complex iSCSI or Fiber Channel architecture.  However, SAS only scales so far.  If you want to expand beyond a handful of servers, you may want to consider one of the iSCSI or Fiber Channel variants.

The SAS architecture is well supported by vSphere, Hyper-V and XenServer, so you can use your hypervisor of choice. Further, the devices support vSphere’s Storage APIs for Storage
Awareness (VASA).

Each controller in the arrays supports up to four SAS connections.  With dual controller units, there are eight SAS connectors available.

Array features

All of the products in the MD3200 series support a number of different data security and protection features, including:

• Snapshots.  These have been around for quite some time.  These are just point in time copies of data.  With snapshots, administrators can often very quickly and easily revert to an older version of a running system with just a few mouse clicks.
• Virtual Disk Copy.  This is a replication feature, which enables quick and easy data protection and backup and recovery.
• Instant Secure Erase.  When arrays are decommissioned, it can be a chore to ensure that the data that was formerly on that array is erased.  That’s where Instant Secure Erase comes in.  Now, disks are easily and permanently erased using this feature.
• Self-encrypting drives.  More and more, organizations are increasingly taking steps to maximize how they protect their data.  One easy way to do this is to use self-encrypting drives, which provide a no-hassle way to add an additional layer of security to the environment.
• Dynamic disk pools.  Dynamic disk pools are a new feature in the MD series.  With this feature, data can be recovered more quickly from failed drives that is possible with a RAID 6 configuration.

Note that some of these features may require the purchase of a separate license key to enable the feature.

Summary

Dell continues to position EqualLogic and Compellent above the MD series, but for those needing massive capacity and scalability without some of the enterprise level features that might be found in the higher-level lines, the MD series might be worth a look.