SanDisk G-RAID Mirror Review: Fast, Secure Hard Drive Storage and Many Features

WD’s G-RAID Mirror is an external enclosure that holds two 3.5-inch hard drives. Provides up to 48TB of storage with drives in striped (RAID 0) mode, or half the storage in mirrored mode RAID 1. It also features a Pro Blade SSD port for SanDisk’s modular NVMe SSDs.

Something you might not realize if you haven’t used a 3.5-inch HDD in a while: It’s much faster than before. In RAID 0, G-RAID mirrors can deliver data at over 400 MBps. This is not your father’s RAID box.

Additional resources: To learn more about the competition, check out our roundup of the best external drives.

G-RAID mirror function

The G-RAID Mirror is a stunning dark gray Thunderbolt 3 2-drive external enclosure offering up to 48TB/24TB (striped/mirrored) capacity. The device measures 5.24 x 8.27 x 4.06 inches (13.30 x 21.00 x 10.21 cm). Depending on the internal drive, it can weigh up to 3.17 kg (7 lbs). If you stand on its non-slip feet, this drive will rarely dance around your desktop. Four hex bolts on each side conceal anchor points for attaching the device to a digital imaging technician cart or adding other hardware.

The back of the G-RAID mirror features two Thunderbolt 3 ports (1 computer, 1 pass-through, see below) and a RAID configuration dual dip switch (JBOD, RAID 0/1). This means it has RAID onboard, which is preferable to the software variety because it can be ported between operating systems without having to install that software. There is also a button to adjust the front LED lighting.

The front of the drive only features the aforementioned LED lights and a removable front grid that allows access to the hard drive for upgrades or replacement. Due to its enormous capacity, rebuilding a RAID 1 array can take a very long time – two hours per terabyte.

The most unusual feature of G-RAID Mirror is the Pro-Blade Transport slot. The somewhat expensive Pro-Blade Transport module is an NVMe SSD in a proprietary enclosure that slides into a slot. It’s super convenient for uploading, offloading, and backing up, and it’s fast enough to boot. However, the Pro Blade system is 20Gbps USB 3.2×2 and the current Thunderbolt (Mac and Windows) implementation does not support USB 3.2×2 at 20Gbps, dropping to 10Gbps. Still fast, but not optimal. Thunderbolt 3/4 supports 20Gbps USB 4, so I’m confused why SanDisk didn’t choose USB 4 for the Pro-Blade Transport or Thunderbolt 3. It looks like it’s targeting Mac users in particular.

Since this drive is primarily targeted at the Apple/video production crowd, the G-RAID Mirror ships formatted as APFS. The case of our test device contained a single 24TB RAID 1 volume. As with most 2.5-inch hard drives, there is no software on the drive.

Challenges of large-capacity HDDs

3.5-inch external hard drives can be very large (it’s crazy to see a 48TB drive on a desktop), but they are harder to back up because they hold so much more data than other media. The only medium with acceptable speed that can store the same amount of data is another hard drive. As a result, the easiest way to prevent data loss due to hard drive failure is to mirror it to another hard drive (RAID 1) or split it across multiple hard drives in another type of fault-tolerant RAID.

How to set up a G-RAID mirror depends on whether it is primary or secondary storage. If it is one component of a larger storage scheme and is backed up (e.g. macOS RAID), we recommend running it in full-capacity striped RAID 0. However, for sole storage, it is recommended to run it as half capacity, mirrored RAID 1.

Unfortunately, mirroring tends to eliminate the price advantage of hard drives over much faster, physically robust, and reliable SSDs. Not completely, but the difference is significantly reduced. Convenient connection…

How much does a G-RAID mirror cost?

G-RAID mirrors are available in capacities of 12TB/6TB, 16TB/8TB, 24TB/12TB, 36TB/18TB, 44TB/22TB, and 48TB/24TB for $660, $750, $1,000, $1,200, $1,400, and $1,600. One of the reasons they each cost more than normal in the US is because of their Thunderbolt 3 connectivity.

This works out to $55/$110, $46.88/$93.76, $41.67/$83.33, $33.33/$66.66, $31.82/$63.64, and $33.33/$66.66 per terabyte (striping/mirroring). As you can see, a 44TB device makes the most sense in terms of price per terabyte.

Last time I checked, prices for 4TB and smaller SSDs had dropped to around $70 per terabyte, but the larger 8TB models were still over $100 per terabyte. Keep this in mind when deciding on your attack storage plan.

If you’re not currently interested in a Pro Blade system, consider picking up a cheaper USB 3.x RAID enclosure like WD’s (SanDisk owner) MyBook Duo.

How does G-RAID mirror work?

The 48TB G-RAID mirror sent by SanDisk arrived configured as RAID 1 (mirroring), as expected from the name. I tested it in that mode and in RAID 0 to see what it can do. (Spoiler alert: There’s a lot more.) We also tested the Pro Blade, which has two modules, and put all three through PCWorld’s test suite for good measure.

The results of all these tests mean there are plenty of captures and images to explore below. To avoid this, we can summarize that the sequential throughput of your hard drives is 175 MBps to 210 MBps in RAID 1 and 350 MBps to 410 MBps in RAID 0.

The Pro Blade reads and writes around 800MBps, well below the 1.8GBps it manages over USB 3.2×2 on a Windows PC. But in reality, even HDDs in RAID 1 are fast enough to handle at least 8K video streams, maybe more. Equipped with the Pro Blade as a separate drive, it can accommodate much higher bandwidth scenarios.

Sustained throughput is much better than using external 2.5-inch hard drives, especially in RAID 0. However, as we will see, if you want fast seek times, these are not the drives you want.

G-RAID Mirror RAID 0 Results

As I said, it’s always good to have a little context, so I’ve included results from PCWorld’s Windows testbed for hard disks in RAID 0 and RAID 1, as well as Pro Blade SSDs. Compared to the recently reviewed Seagate Expansion Desktop hard drive and Pro Blade Transport using USB 3.2×2.

Yes, on Windows the numbers are a bit more impressive. However, Thunderbolt hindered G-RAID’s Pro Blade by limiting it to 10Gbps.

The random numbers on the hard disk are very small compared to the Pro Blade. However, CrystalDiskMark 8’s numbers are still valid even if they are not specifically designed for HDDs.

Jon L. Jacobi / Foundry

Jon L. Jacobi / Foundry

Jon L. Jacobi / Foundry

Results from Pro Blade Transport are included to show what these modules can do at 20Gbps on a real 3.2×2 bus, and how clogged the Pro Blade in a G-RAID mirror is by the Thunderbolt 3 bus.

Transport results on Mac are the same as those on the port built into G-RAID Mirror.

Obviously, once again the G-RAID mirror in RAID 0 was significantly faster at writing 450GB than in RAID 1.

John L. Jacobi

John L. Jacobi

John L. Jacobi

The G-RAID Mirror’s fan is quite noisy when it starts up. But most of the time my Mac Studio fans make just as much noise, and that’s barely any noise at all. To be fair, my office has a test bed and NAS box that are buzzing most of the time, so my tolerance for white noise is very high. However, because the read/write heads are moving, there is also noise. This could be a problem if you haven’t used your hard drive in a while. You could argue that there needs to be more noise-deadening material inside, but this tends to trap heat and noise, which would be bad.

The user guide I downloaded says that you should only turn off the G-RAID mirror twice when changing RAID modes, which could be interpreted as using the power button. This is wrong. The website information and my experience says that you have to unplug the power twice to switch RAID modes.

Overall, G-RAID mirrors are much faster in RAID 0 than in RAID 1. That means you might be better off using two models with less capacity, one that uses RAID 0 and macOS’ own RAID 1 mode. Then, when you need real speed, you can use the Pro Blade and leave your HDDs safely mirrored.