Promise Pegasus2 M4 (4x1TB) Thunderbolt 2 DAS Review
by Kristian Vättö on September 12, 2014 9:00 AM EST- Posted in
- Storage
- Thunderbolt
- m4
- Promise
- DAS
- Thunderbolt 2
- Pegasus2
Final Words
It is clear that the Pegasus2 M4 is a niche product. Any user that does not require portability will be better served by the R4, which is a similar 4-bay Thunderbolt 2 device but with 3.5" hard drives instead of 2.5" drives. As a result it is physically larger but should provide better performance since 3.5" hard drives tend to be faster than their 2.5" siblings. We have not tested the new R4, but we did test the original R6 when it was released and the performance was better than what the M4 offers. The R4 is also more cost efficient and it retails for $1,499 at the Apple Online Store, but that includes 8TB of data so that works out to be $187.50 per terabyte whereas the M4 costs $250 per terabyte.
Furthermore, a single 3.5" external hard drive can beat the M4 in capacity while costing a fraction of the M4's price, and it provides the same or even higher level of portability. That leaves redundancy and performance as the M4's advantages. Since the M4 supports RAID 5 and RAID 6, it can withstand one or two hard drive failures without losing any user data. The performance is also much better than what you can get from single 3.5" drives, which usually max out at around 200MB/s, whereas the M4 manages over 350MB/s in RAID 5 configuration.
I did notice one irritating thing in the M4, however. The fan in the M4 makes a fairly loud noise even when the device is idling. Unfortunately I do not have a proper decibel meter to provide an objective measure of the noise, but WebPAM PRO showed the fan speed to be 2,400rpm, which certainly sounds high. I would not say the noise is too loud to distract me while working, but it is clearly distinguishable over the noise that the three desktops in my office create.
Another thing I have a slight problem with is the lack of additional capacity points. 4TB is not much for a video professional, especially if 4K video is being stored, and 1.5TB and 2TB 2.5" 9.5mm hard drives are not that expensive anymore. A 2TB 2.5" 9.5mm hard drive costs $127 online while a similar 1TB drive costs $65, so the price is exactly double. It is understandable that Promise must have high margins because these are not mainstream products that sell in high volumes and thus I can see the cost sensitivity issue with higher capacities, but a 4x2TB configuration at $1,499 would still leave Promise with a ~50% margin on the hard drives.
All in all, the M4 targets a fairly small niche. I can only think of video professionals (maybe photo and audio to some extent) that would see the value in the M4 because if you do not need portability, redundancy, and high performance, there are better options in the market. However, if you need all three (e.g. for on-set video editing), the M4 does the job.
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Zak - Friday, September 12, 2014 - link
The 4xSSD performance is a little disappointing indeed. That would be #1 reason to get this enclosure. I get faster speeds, over 1GB/s reads, out of two SSDs on the onboard Intel RAID controller.simonrichter - Friday, October 3, 2014 - link
I agree, it is rather disappointing and it makes it an average storage devices that cannot match up to the top ones on the market (for example http://www.consumertop.com/best-computer-storage-g... ). But it should be interesting to see if they release an updated version of it.jonb8305 - Wednesday, October 15, 2014 - link
Promise has an SSD version of the m4 with way better performance than what was stated here.bill.rookard - Friday, September 12, 2014 - link
While I do somewhat see the use of a device like this, I'm not sure I see it really serving any real niche effectively.It's made to use small, portable drives, but it's not portable as it requires external power.
It should be quick, but it's limited by the internals to about 1/4 of it's theoretical top speed.
It uses the expensive Thunderbolt interface to be fast, but again, it's limited internally.
It offers four drives, but keeps them to 2.5" drives without making the unit truly portable.
It offers four drives for capacity, but then only offers 1TB drives.
This device just seems like a whole series of compromises without really SERVING a niche effectively.
JohnMD1022 - Tuesday, September 16, 2014 - link
Why not offer it as a bare box?Drizzt321 - Friday, September 12, 2014 - link
How about running the SSDs as single disks and using Windows RAID to check performance. Cut out the RAID controller, which them will leave us the SATA controller to test that to see if it's the RAID controller, or the SATA controller.And I agree, it's too bad it can't be bus-powered. Maybe when USB3.1 with Type-C connectors comes along it'd be able to power something like this. 100W is quite a bit of power, especially with 2.5" drives!
repoman27 - Sunday, September 14, 2014 - link
If Kristian was correct in his guess that there's a PMC-Sierra PM8011 lurking under that heat sink, which is quite likely seeing as Promise uses that chip in several other products already, it's an RoC (RAID-on-Chip). So the SATA (actually SAS in this case) controller and the RAID controller aren't terribly separable.The performance scaling actually looks damn near perfect with the HDDs, and indicates that the RoC is actually a beast for the intended workload. I'm not sure why Kristian thought RAID 5 read performance would be higher. If you only stripe across three drives and write parity data to the 4th, it would be pretty challenging to read back faster than 3x the maximum a single drive can muster. In this case, the Pegasus2 M4 hit 355.5 MB/s vs. 120 MB/s for a single drive, or near as makes no difference 3x. And the 15% performance hit for sequential reads in RAID 10 doesn't seem too egregious, especially seeing as random reads went up by almost 17%.
Kristian never mentioned what he was using for SSDs or if they were all identical. I'm guessing whatever he used, the RoC simply wasn't tuned for it. Although who knows, maybe the same test on a Mac would have yielded radically different results.
100 W may be a lot for 4x 2.5-inch HDDs, but the Pegasus2 M4 appears to be packing a compact internal 110 W PSU from FSP. That's nuts!
HigherState - Friday, September 12, 2014 - link
I know they say performance on win vs mac should be close, however those numbers are so dissapointing that its possible that its os driver related as well. Someones bound to have an old MBP to lend you for the testrepoman27 - Sunday, September 14, 2014 - link
Well, the performance of the unit as it shipped isn't really disappointing at all. I mean, aside from not using something slightly peppier than the Toshiba drives, like maybe HGST Travelstar 7K1000's, what was Promise supposed to do?Clearly the SSD experiment was performed with a set of drives that had in no way been validated against Promise's firmware.
The_Assimilator - Friday, September 12, 2014 - link
Or you could spend $700 on four 7200rpm 4TB 3.5" drives and a cheap RAID controller card, and build a RAID-10 setup that also wouldn't be portable, but would be fast and have 8 times the capacity of this POS.