Review: OWC Express 4M2 NVMe SSD RAID – When Speed’s the Need

[ Read my product review disclosure statement here.]

This review of the Express 4M2 SSD RAID wraps up my three-part review of high-speed SSD storage from OWC. My other two reviews covered the OWC Thunderblade and OWC Envoy Pro FX.

All three of these are really fast. While this much speed will be overkill for HD editing, these are invaluable for edits involving multicam and large frame sizes. Here I also provide tips on which to pick for your editing and the best options for formatting.

OWC loaned me an 8 TB unit for two weeks so I could write this review.

EXECUTIVE SUMMARY

The OWC Express 4M2 NVMe SSD RAID holds up to 32 TB of storage, spread across four Aura NVMe SSDs. Powered from the wall, it can be placed horizontally or vertically. It supports both Mac and Windows systems and is formatted by the end user.

Depending upon how the system is formatted, it comes close to fully saturating a Thunderbolt 3 bus with speeds approaching 2,800 MB/second. While the unit ships without any storage, you can easily add up to four Aura P12 NVMe SSDs. I cover this in the Installation section below.

NOTE: For best results, all four SSDs should match for model and storage capacity.

This all-metal enclosure is solidly-built, rugged and will last for years. Installation is not for the fumble fingered – I dropped one itty-bitty screw and spent ten minutes searching for it. But all parts seem to be high-quality and the ultimate fit is excellent.

Install the SSDs, plug the unit into wall power using a small power brick, connect it to a Thunderbolt port and you are ready to format it. It has two Thunderbolt ports on the back so you can loop through this device to connect other Thunderbolt devices (up to six). It also has a DisplayPort connection on the back to make it easy to attach a monitor directly to the unit.

While no SSD has the capacity of spinning hard drives, no spinning media can touch these for speed, ruggedness and minimal noise. Heat is dissipated using a 2″ fan that vents out the bottom of the unit. I never heard any fan noise. However, putting my ear within inches of the unit, I did hear a low hum. I do not consider it in any way objectionable.

NOTE: If you want an SSD that is DEAD quiet, consider the Thunderblade which has no fan and no moving parts.

If you need speed combined with greater storage than one SSD provides, the Express 4M2 is an excellent choice. If I didn’t already own a Thunderblade, I’d consider buying one of these for myself.

Manufacturer: OWC
Product: Express 4M2
Website: https://eshop.macsales.com/shop/express-4m2
Price: $249 (US) with no storage. $349 (US) including SoftRAID XT.
Storage ranges from about $200 (1 TB) to $1,520 (16 TB)

INSTALLATION

The OWC Express 4M2 box contains the storage unit, power brick and AC cable and a high-quality 0.7 meter Thunderbolt cable.

When you compare it in size to a typical 4-drive spinning media RAID, it is much smaller, quieter and lighter. And MUCH! less sensitive to abuse.

Two Phillips screws on the back attach the cover to the innards.

Remove one Phillips screw on each side of the fan, lift the fan off and disconnect the power cable. The all-metal construction is solid and everything fits nicely in place. I guess you could mess this up if you decidedly don’t pay attention, but for most of us, disassembly takes just a few minutes. You’ll need a really small point on your screwdriver.

Carefully unwrap an SSD blade, touching it only on the edges and NEVER on the gold contacts. Push the SSD firmly into the dock (it only goes in one way and clicks), then screw the back down.

Add all four SSDs to the motherboard, making sure to screw each down so it doesn’t come loose. (Coming loose would be bad.)

NOTE: You can easily use the Express with only one SSD. However, for the fastest performance and greatest capacity, buy four matching SSDs to fully populate the board.

Also, OWC support tells me there is no performance difference as storage capacity increases. So buy the storage you need – the speeds will be the same.

As you look at the back, once you get everything screwed back together, you’ll see two Thunderbolt 3/4 connectors along with one DisplayPort and power connector.

Once everything is installed and connected, formatting the drive is the same as any other Mac or Windows storage. For SSDs on the Mac, always format using APFS, not HFS+.

WHICH TO PICK?

• If you need the fastest speed in the smallest package, get the Envoy Pro FX.
• If you need maximum storage with blazing speed, with zero installation, get the OWC Thunderblade.
• If you need maximum storage, blazing speed and the potential to upgrade the storage as larger SSDs are released, get the OWC Express 4M2. The Express is also marginally faster than the Thunderblade.

SPEED TEST SUMMARY

I ran 98 different speed tests on this unit. I used an M1 Pro MacBook Pro with 32 GB of RAM and running macOS Ventura 13.4. Speeds were measured using the full version of AJA System Test. All speed tests were run at least four times. For RAID 4 and RAID 5 the results varied so much that I ran each test six times.

NOTE: All speed tests were run on drives containing no data; i.e. empty.

Here’s what I learned:

• If you want the fastest speed with maximum storage capacity, format the unit as RAID 0 using Apple Disk Utility.
• The faster the read speed, the more multicam playback streams this unit will support. Based on past tests with the Thunderblade, the speed of the Express will support dozens of HD or 4K multicam streams and from 6-10 8K streams.
• Only purchase SoftRAID XT if you want to format the drive as RAID 4 or RAID 5.

NOTE: Here’s a tutorial explaining RAID levels.

• When formatted as RAID 4 or RAID 5, the Express 4M2 shows significant write speed fluctuations; varying up to 600 MB/second. These don’t appear when formatted as RAID 0.
• It is easily possible to format this unit in a variety of configurations containing different numbers of drives; i.e. JBOD, RAID 1, RAID 0. For example, on my Thunderblade I formatted one drive as a Time Machine backup, then created a three-drive RAID 0 for media editing.
• Finally, even a 3-drive RAID 4 is fast enough to support virtually all media editing.

COOL CHARTS

First, I compared the single drive read and write speeds between the Envoy Pro FX, Thunderblade and Express 4M2. Not surprisingly the single NVMe drive of the Envoy Pro FX easily beat a single blade in the other two devices.

It was interesting, though, to note that the Express 4M2 was 4 – 5% faster than the Thunderblade. The SSDs of both are the same.

Next I compared the read and write speeds of a 4-drive RAID 0 when formatted by Apple Disk Utility vs. OWC SoftRAID. The results varied by less than 1%, meaning that Disk Utility is perfectly fine for formatting RAID 0 or 1.

SoftRAID will be necessary to create either RAID 4, RAID 5 or RAID 10.

I next looked at read and write speeds by RAID type. As expected, RAID 0 was the speed demon. As expected, the read speeds on RAID 4 (which is optimized for SSD storage) were much faster than RAID 5. Write speeds for RAID 4 & 5, though, were pretty much even.

RAID 10 was a surprise. This combines the speed of RAID 0 with the data redundancy of RAID 1. Write speeds were faster than all other formats except RAID 0, while read speeds were almost equal to RAID 0. Very impressive. However, RAID 10 holds half the capacity of RAID 0.

I was also struck by how fast read speeds were for a 2-drive RAID 1.

What I didn’t expect, though, was the significant speed variation between tests when the drive was formatted as RAID 4 or RAID 5. RAID 4 varied by as much as 500 MB/second. RAID 5 varied by more than 600 MB/second. I have no idea why.

RAID 0, 1, and 10 showed speed variations of 1% or less.

NOTE: The way to read the variation numbers is that speeds will vary plus or minus the number at the top of the bar.

Finally, I looked as RAID 0 speeds based upon the number of drives in the RAID. As expected, write speeds were fairly linear. However read speeds quickly accelerated so that the performance of a 3-drive RAID 0 was close to that of a 4-drive.

WHAT DOES ALL THIS MEAN?

At the end of the day, the reason you buy fast storage is to get work done faster, support larger frame size video editing or handle more multicam streams. So, to put this into real-world terms, I measured speeds using Blackmagic Design Disk Speed test.

A 3-drive RAID 4, which provides data redundancy, supports all video playback formats until 8K.

A 4-drive RAID 4 supports all video playback formats until 12K.

A 3-drive RAID 0, which does not provide data redundancy, supports all video formats except 12K/60.

A 4-drive RAID 0, supports all video formats, period.

As for multicam, there’s no practical limit to the number of HD or 4K streams this supports. Here’s a review on Final Cut Pro with more details. And this one discusses Premiere Pro.

A QUICK NOTE ON EXPANDABILITY

One of the benefits to formatting a drive using RAID 4 or RAID 5 is that you can expand the system by replacing one SSD with a larger capacity, then allowing the RAID to rebuild.

Repeat this procedure to replace all four SSDs. Once complete the RAID will automatically reconfigure to support the additional storage. This feature is not available with either the Envoy Pro FX or Thunderblade. It also can not be done if the drive is formatted as RAID 0, 1 or 10.

RAID 0 provides maximum speed. RAID 4 & 5 provide data redundancy and potential expandability. RAID 1 provides a good compromise with good read speeds and total data redundancy.

SUMMARY

The OWC Express 4M2 is really, really fast. Well-built. And, provided you format your storage as RAID 4 or 5, expandable. In my case, I would format this as RAID 0 knowing that I need to regularly back up the Express to other, generally slower, storage. If backup is not possible, I’d format this as RAID 10, knowing that I would lose half my capacity.

In many cases, the Express 4M2 outperformed the Thunderblade. If more speed is essential to your work, the Express 4M2 delivers it in a small, well-built, dependable box.

EXTRA CREDIT

Here’s a spreadsheet with all the results from my tests. The charts were based on these results.

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