Drobo 5N2 5-bay NAS Review - Bonded GbE Made Simple
Performance, Pricing, and Conclusion
For performance testing the 5N2, we went with a low-tech approach involving file copies to and from the unit across our LAN. The switch used was an older Netgear JGS524v1 unmanaged switch. For variety and additional data points, the two PCs were running Windows 8.1 and Windows 10. With 5x 8TB WD Reds installed and with Network Interface Bonding *disabled*, this is an example of a file copy to the 5N2 from two different systems on our network:
Standard single NIC configuration, simultaneous copy from two systems to 5N2
Note the total Gigabit throughput (112.1 MB/s) must be split between both systems. This is what you would typically see with any single GbE connected NAS. Now let's see what happens after we check the Network Interface Bonding box in the 5N2's configuration (note: this requires the 5N2 to reboot for this low-level change to take effect).
Bonded NICs, simultaneous copy from two systems to 5N2
And with that simple change, we are up to 176.1 MB/s, though it does bounce around a bit, as we are running up against throughput/latency limits of BeyondRAID plus relatively slow 5400 RPM NAS drives due to writing two files simultaneously.
Bonded NICs, simultaneous copy from 5N2 to two systems
Since HDDs can't buffer reads as well as they can buffer writes, reading two separate files simultaneously sees even slower speeds, though we are still doing better than the ~50 MB/s we would see to each system without Bonded NICs at play.
Bonded NICs, simultaneous copy from 5N2 to two systems (reading the same file)
To show that it is the disks that are the limit here, two systems accessing an identical file fully saturates both links simultaneously. What we can tell here is that the network is not the bottleneck and that Drobo's NIC bonding implementation is working quite well here.
Bonded NICs, simultaneous copy from 5N2 to two systems (mSATA cache installed)
Having an mSATA SSD installed helps with these simultaneous file reads, as well as with random reads overall, as the Drobo can keep an extra copy of selected content on a very low latency device. Those wanting improved mixed workload and small random performance can also skip the mSATA option and simply install SATA SSDs in place of HDDs. Costly indeed, but certainly doable and supported.
Bonded NICs, single copy from 5N2 to single system after large file deletion
It is worth noting that since Drobo keeps itself aware of the contents of its volumes, file deletions and other activity may lead to some background cleanup and garbage collection of unused BeyondRAID data blocks. During testing, I was able to trigger one such cleanup event, which became apparent as the drives were busy thrashing a bit during one of the subsequent copy attempts. Note that faster drives, the mSATA cache, etc. will help these operations complete more quickly. I don't see this as a major issue - just something to be aware of before performing large operations while expecting full speed response to other users.
Bonded NICs, simultaneous copy from two systems to 5N2 (5x 160GB VelociRaptor)
Above is a repeat of the second test from earlier on this page, but this time I swapped in a set of WD VelociRaptors in an attempt to evaluate the sensitivity of seek times on multi-stream performance. As you can see, things improved considerably. We are now up to 186.2 MB/s combined throughput. The drives we swapped in had lower sequential performance than the 8TB Reds, but faster seeks, meaning they could more quickly toggle between the pair of streams being applied here.
The Drobo 5N2 is priced at $499 and is currently available for order direct from drobostore.com. There are a couple of promos running until April 4th, 2017:
- $50 discount to prior Drobo FS and 5N customers
- US customers get a free GelaSkin with their 5N2 purchase
This price is actually pretty good considering the other 5-bay solutions currently on the market. Synology products do include some additional flexibility and connectivity (you can connect additional external HDDs via USB, etc), but the BeyondRAID flexibility and simpler configuration of the Drobo are definitely appealing to some.
Drobo's 5N2 combines their long-standing tradition of dead simple setup and configuration with increased speed through a pair of bonded Gigabit Ethernet interfaces. Bonding takes the 5N2 from a device that can perform solidly on two separate networks to one that can offer almost twice the performance on a single subnet. While Drobo increased the processing capability to support the additional network throughput, we were beginning to encroach upon the seek performance of NAS-grade HDDs when attempting to serve two simultaneous Gigabit streams. DroboApps has grown to cover the majority of things you would possibly want to run on a home NAS, and DroboDR offers off-site backup (to another Drobo). Overall, the combination of Drobo's BeyondRAID, bonded Gigabit Ethernet, 5 drive bays, and a competitive price point, make for a compelling NAS package worthy of serious consideration for any home or small business network storage needs.
After several prior 'N' Drobos falling short of our expectations, the 5N2 is a good performer at a great price, and it becomes my default recommendation for a 5-bay NAS.