Technology content trusted in North America and globally since 1999
8,287 Reviews & Articles | 63,009 News Posts

NVMe NAS Cache: Higher Speed or More Capacity?

By: Chris Ramseyer | USB Drives in Storage | Posted: Apr 19, 2019 3:00 pm

CIFS Performance Testing

 

Testing Notes

 

nvme-nas-cache-higher-speed-more-capacity_5

 

For this article, we used the Synology DS1819+. This system doesn't support NVMe acceleration out of the box. The system does provide a single PCIe 3.0 x8 slot. With it, you can install a 10bE add-in card or a dual M.2 2280 accelerator card that enables NVMe SSD cache. Sadly, you can't use two cards at the same time with this NAS.

 

The NAS' configuration software allows us to configure a read-only cache or a read and write cache. The latter requires two drives to ensure data integrity. The read-write cache combines the drives in RAID 1 to mirror the data.

 

For hard disk drives, we used eight Seagate IronWolf Pro 12TB in RAID 6.

 

Sequential Read Performance

 

nvme-nas-cache-higher-speed-more-capacity_50

 

The default cache setting for the Synology DS1819+ ignores sequential data. We unchecked the box to allow the cache drives to work with all data, sequential and random. The bottleneck in this configuration is the 1-gigabit Ethernet that limits throughput.

 

 

Sequential Write Performance

 

nvme-nas-cache-higher-speed-more-capacity_51

 

nvme-nas-cache-higher-speed-more-capacity_52

 

nvme-nas-cache-higher-speed-more-capacity_53

 

Even though the Intel Optane SSD doesn't suffer from steady-state performance loss like flash-based drives, the 960 Pro never drops below the 115 MB/s that is the network bottleneck.

 

Sequential Mixed Workloads

 

nvme-nas-cache-higher-speed-more-capacity_54

 

For sequential workloads, NVMe cache acceleration is a wash if your network configuration is limited to 1-gigabit. With all four-cache configurations, we didn't observe any performance or consistency increase over the all HDD array.

 

Random Read Performance

 

nvme-nas-cache-higher-speed-more-capacity_55

 

nvme-nas-cache-higher-speed-more-capacity_56

 

The tables turn when we start working with random data. With pure reads, the two Optane tests (read and read + write cache) outperform the other configurations. The two 960 Pro accelerated configurations follow. The pure HDD result is all the way at the bottom of the chart. The furthest gap between the HDD only and the highest cache result shows a difference of around 14,000 IOPS or around a 1400x increase!

 

Random Write Performance

 

nvme-nas-cache-higher-speed-more-capacity_57

 

nvme-nas-cache-higher-speed-more-capacity_58

 

nvme-nas-cache-higher-speed-more-capacity_59

 

nvme-nas-cache-higher-speed-more-capacity_60

 

The Synology DS1819+ doesn't deliver a typical random write preconditioning curve like we see with enterprise SSDs. Even with a write cache, the results are very segmented with a lot of inconsistency. The system will use DRAM to cache incoming random write, either from the system itself or on the HDDs.

 

The highest IOPS we scored on this test were actually from the HDD only configuration, and that's due to the high-speed DRAM that is faster than both flash and 3D XPoint memory. There is a very limited amount of DRAM in place to catch the random writes, so even with the DRAM the results are inconsistent.

 

Random Mixed Workloads

 

nvme-nas-cache-higher-speed-more-capacity_61

 

nvme-nas-cache-higher-speed-more-capacity_62

 

The random mixed workload shows gives us our first real difference between the 960 Pro and Optane configuration. At low queue depths, the Optane 800P cache with both read and write acceleration doubles the performance of the 960 Pro read and write acceleration configuration. The results cross over at high queue depths where the 960 Pro takes a significant lead.

    PRICING: You can find the product discussed for sale below. The prices listed are valid at the time of writing, but can change at any time. Click the link below to see real-time pricing for the best deal:

     

    United States: Find other tech and computer products like this over at Amazon`s website.

    United Kingdom: Find other tech and computer products like this over at Amazon UK`s website.

    Canada: Find other tech and computer products like this over at Amazon Canada`s website.

    We at TweakTown openly invite the companies who provide us with review samples / who are mentioned or discussed to express their opinion of our content. If any company representative wishes to respond, we will publish the response here.

Related Tags

Got an opinion on this content? Post a comment below!
loading