Actual Write Speeds on QNAP: NVMe vs SATA SSD vs HDD writing speed in RAID1 and RAID0

TL;DR: If you’re running your NAS on a 1G/2.5G network, don’t bother spending extra on SSDs. Hard drives will give you nearly identical performance in such setups.

I recently ran a series of tests on my QNAP NAS to determine if there’s a real performance benefit from using different media types. While it’s well-known that SSDs are faster than HDDs, we often overlook the fact that most NAS setups operate over a network. Network speeds can be the bottleneck, and in many cases, these bottlenecks may nullify any performance gains you’d expect from using faster media like SSDs.

Setup Overview

I configured my QNAP NAS with the following variables:

• Network Speeds: 1G (Gigabit Ethernet) , 2.5G (2.5 Gigabit Ethernet), 10G Ethernet cabled directly to a PC
• Media Types: NVMe SSD, SATA SSD, and HDD (Hard Disk Drive)
• RAID Configurations: RAID 0 (striped) and RAID 1 (mirrored) since I only had 2 drive each. Although RAID 0 isn’t common or advisable for most users, I wanted to see if its theoretical doubling of speed held true—and it almost did.
• SMB Write test using Robocopy : I used Robocopy to test write speeds across different combinations of network, media, and RAID. Each test involved transferring large files (3GB+) to measure write speeds. Each test was performed using a single network at a time (no SMB multichannel).
• No CPU bottleneck : I used a QNAP TS-855X with 8GB RAM, not an entry level machine, just to make sure that there was no CPU bottleneck

Actual limits of 1G, 2.5G and 10G Networks are 115MB/S, 285 MB/S and 1020 MB/S

No matter how fast your drives are, a 1G network won’t let you go beyond 115 MB/s, and even a 2.5G network caps out at 285 MB/s. Thats why if you see the results table , you will notice that all types media under RAID1 and RAID0 performs the same with 1G and 2.5G network.

It’s only with a 10G network that the differences begins to show - SATA SSDs hit 495 MB/s in RAID 1 and nearly doubled to 855 MB/s in RAID 0. NVMe SSDs are still capped at 1020 and can not reach their limits of 2500-3000 MB/Sec. Even 10G network is limiting factor for NVMe.

SATA SSD can deliver upto 500 MB/S , HDD upto 270 MB/S - combine them with network speeds and you get an idea

Now Since you know the network speeds, you can see how a combination of media would work. For Example HDDs max out at 270 MB/s, so they are ok on 2.5G connection but limited on 1G. SATA SSDs delvier upto 500 MB/s and peak out only on a 10G network ( Say 4 SATA SSDs in RAID5 with 3 writing in parallel). NVMe SSDs are limited even on a 10G netoverkill unless you’re running a high-bandwidth connection like 25G or above.

Actual Results : SATA SSD writing speed vs NVMe writing speed vs HDD Writing speed

Here is the table showing you all the actual speeds

Conclusion

• 1G Network? Stick to HDDs
  Don’t waste money on SSDs if your NAS is on a 1G connection. Even with RAID 0 or NVMe SSDs, the network speed will bottleneck your performance.
• 2.5G Network? HDDs or SATA SSDs Work:
  With a 2.5G connection, HDDs can deliver their maximum performance, while SATA SSDs will start showing some improvement. NVMe is still overkill here. Team up your 1G or 2.5G connections if you have multiples to see real benefits
• 10G Network? Time for SSDs:
  A 10G connection is where SATA SSDs and NVMe SSDs shine. Well, NVMe SSDs will still be limited by the network, so only invest in them if your workflow requires their internal NAS speeds. BTW QNAP has 25G, 40G and even 100G cards and if you want to see real speed benefits, you will have to go with them.