Synology DS2015xs Review: An ARM-based 10G NAS
by Ganesh T S on February 27, 2015 8:20 AM EST- Posted in
- NAS
- Storage
- Arm
- 10G Ethernet
- Synology
- Enterprise
Miscellaneous Aspects and Final Words
In order to keep testing consistent across all 8-bay units, we performed all our expansion / rebuild testing as well as power consumption evaluation with the unit configured in RAID-5. The disks used for benchmarking (OCZ Vector 4 SSDs) were also used in this section. The table below presents the average power consumption of the unit as well as time taken for various RAID-related activities.
| Synology DS2015xs RAID Expansion and Rebuild / Power Consumption | ||
| Activity | Duration (HH:MM:SS) | Avg. Power (W) |
| Single Disk Init | 00:01:00 | 18.64 W |
| JBOD to RAID-1 Migration | 00:19:14 | 20.91 W |
| RAID-1 (2D) to RAID-5 (3D) Migration | 00:25:07 | 23.95 W |
| RAID-5 (3D) to RAID-5 (4D) Expansion | 00:23:48 | 26.92 W |
| RAID-5 (4D) to RAID-5 (5D) Expansion | 00:24:19 | 29.86 W |
| RAID-5 (5D) to RAID-5 (6D) Expansion | 00:24:20 | 32.82 W |
| RAID-5 (6D) to RAID-5 (7D) Expansion | 00:22:49 | 35.8 W |
| RAID-5 (7D) to RAID-5 (8D) Expansion | 00:20:03 | 38.79 W |
| RAID-5 (8D) Rebuild | 00:13:12 | 32.77 W |
We don't have any comparison graphs for RAID rebuild duration / power consumption since other 8-bay units were subject to RAID operations with 4 TB hard drives. The usage of 120 GB SSDs prevents us from making any concrete conclusions about the efficiency of Synology's expansion, migration and rebuild operations.
Concluding Remarks
Coming to the business end of the review, it is clear that the presence of two 10G ports enables the DS2015xs to achieve high transfer rates. Compared to the last 10G desktop NAS we evaluated (based on an Intel Xeon platform), the power consumption is much lower At $1400, the DS2015xs is affordably priced, considering the 10G features built into it. DSM's business-oriented features (very important for the DS2015xs's target market) are stable and industry-leading.
The above advantages aside, there are certain areas of concern / scope for improvement: Synology needs to supply a way to test the network performance (provide an optimized iPerf package) isolated from the storage subsystem. The SoC vendor, Annapurna Labs is in the process of being purchased by Amazon. It is not clear what effect that would have on the DS2015xs's successors. It is likely that other ARM server vendors might want to make a play for future products in the lineup.
It is impossible not to conclude this review without a car analogy for the DS2015xs. The presence of dual 10G ports and eight native SATA III ports might delude consumers into thinking that they are purchasing a Ferrari. Unfortunately, consumers only get a souped up Volkswagen engine inside. That said, with tempered expectations, the $1400 Synology DS2015xs can fulfill the role of a cost-effective power-efficient high performance NAS.
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chrysrobyn - Friday, February 27, 2015 - link
Is there one of these COTS boxes that runs any flavor of ZFS?SirGCal - Friday, February 27, 2015 - link
They run Syn's own format...But I still don't understand why one would use RAID 5 only on an 8 drive setup. To me the point is all about data protection on site (most secure going off site) but that still screams for RAID 6 or RAIDZ2 at least for 8 drive configurations. And using SSDs for performance fine but if that was the requirement, there are M.2 drives out now doing 2M/sec transfers... These fall to storage which I want performance with 4, 6, 8 TB drives in double parity protection formats.
Kevin G - Friday, February 27, 2015 - link
I think you mean 2 GB/s transfers. Though the M.2 cards capable of doing so are currently OEM only with retail availability set for around May.Though I'll second your ideas about RAID6 or RAIDZ2: rebuild times can take days and that is a significant amount of time to be running without any redundancy with so many drives.
SirGCal - Friday, February 27, 2015 - link
Yes I did mean 2G, thanks for the corrections. It was early.JKJK - Monday, March 2, 2015 - link
My Areca 1882 ix-16 raid controller uses ~12 hours to rebuild a 15x4TB raid with WD RE4 drives. I'm quite dissappointed with the performance of most "prouser" nas boxes. Even enterprise qnaps can't compete with a decent areca controller.It's time some one built som real NAS boxes, not this crap we're seeing today.
JKJK - Monday, March 2, 2015 - link
Forgot to mention it's a Raid 6vol7ron - Friday, February 27, 2015 - link
From what I've read (not what I've seen), I can confirm that RAID-6 is the best option for large drives these days.If I recall correctly, during a rebuild after a drive failure (new drive added) there have been reports of bad reads from another "good" drive. This means that the parity drive is not deep enough to recover the lost data. Adding more redundancy, will permit you to have more failures and recover when an unexpected one appears.
I think the finding was also that as drives increase in size (more terabytes), the chance of errors and bad sectors on "good" drives increases significantly. So even if a drive hasn't failed, it's data is no longer captured and the benefit of the redundancy is lost.
Lesson learned: increase the parity depth and replace drives when experiencing bad sectors/reads, not just when drives "fail".
Romulous - Sunday, March 1, 2015 - link
Another benefit of RAID 6 besides 2 drives being able to die, is the prevention of bit rot. In Raid 5, if i have a corrupt block, and one block of parity data, it wont know which one is correct. However since RAID 6 has 2 parity blocks for the same data block, its got a better chance if figuring it out.802.11at - Friday, February 27, 2015 - link
RAID5 is evil. RAID10 is where it's at. ;-)seanleeforever - Friday, February 27, 2015 - link
802.11at:cannot tell whether you are serious or not. but
RAID 10 can survive a single disk failure, RAID 6 can survive a failure of two member disks. personally i would NEVER use raid 10 because your chance of losing data is much greater than any raid that doesn't involve 0 (RAID 0 was a afterthought, it was never intended, thus called 0).
RAID 6 or RAID DP are the only ones used in datacenter for EMC or Netapp.