WD Red SN700 NVMe SSD Review – Does it Deserve Your Cache?

Review of the WD Red SN700 M.2 NVMe SSD for NAS Drives

Why should you put the WD Red SN700 SSD in your NAS? It’s a fair question. Western Digital (WD) has been in the SSD market for quite a few years now, with a lot of in-house R&D at their disposal and their past consolidation with Sandisk resulting in some generally impressive Solid State drives from the brand available to home/business users. One big plus to the WD range of SSD media (and indeed hard drive media) is their rather easy to follow colour coding system on their portfolio, with SSD/HDDs for NAS/SMB server use being branded with the ‘WD Red’ title. Although the WD Red range of NAS hard drives has been around for a long time and is available in numerous forms (RED, Red Pro, Red Plus), their SSD series has been a little more gradual in its release strategy, with their WD Red SA500 NAS SSD (in SATA 2.5″ and SATA M.2) being the only real move from them. That is of course until now, with their new M.2 NVMe SSD for NAS/Server use, the WD Red SN700. With more and more NAS server systems (both desktop and rackmount) arriving on the scene with dedicated M.2 NVMe SSD slots (first real example as earlier as 2017/18 with the DS918+), WD has really taken their time of producing a dedicated NVMe SSD for NAS users. So, what is it that makes the WD Red SN700 SSD stand out? What makes it NAS/Server optimised and ultimately in our SN700 review we want to figure out if it deserves your cache*?

*I’ll get my coat….

WD Red SN700 SSD Review – Quick Conclusion

There is a lot to like about the WD Red SN700 SSD. For a start, this is clearly one of the highest endurance SSDs available in their current home/SMB lineup of drives at 0.7-1.0DWPD (capacity dependant) and if you are looking for an SSD for your Synology or QNAP system as an area of write-enabled cache (or Read/Write), then you are definitely going to feel better about that lifespan. Equally, I like that WD has gone into this with a broad range of capacities to complement the varying degrees of storage potential in the average user (even 2-Bay NAS like the DS720+ or TS-251D have PCIe/M.2 expandability available by default), from as little as 250GB and all the way up to 4TB on that petite little M.2! Even when we pushed the drive in both standalone benchmarks in our test machine and in both Synology/QNAP NAS usage for caching and storage pools, the drive maintained expected performance and higher in every test. In direct comparison with it’s most comparable PCIe3 drive from competitor Seagate, the Ironwolf 510 SSD for NAS, the WD Red SN700 is a clearly higher-performing drive in read, write, durability and 4K IOPS (though the Ironwolf does have an inclusive 3-year data recovery services – a bit questionable in utility for cache recovery though). I do question the somewhat delayed arrival of a PCIe Gen 3×4 SSD for NAS as the move towards PCIe Gen 4 in NAS is starting in development, as well as the price point of this drive for NAS seemingly ignoring this transition. But if you are looking to add cache to your NAS in 2021 (as well as scaling up random performance or your storage pools in an older system), then the WD Red SN700 SSD is a solid choice and does exactly the things they claim.

EFFECTIVENESS - 8/10
HARDWARE - 8/10
PERFORMANCE - 8/10
PRICE - 7/10
VALUE - 7/10


7.6
PROS
👍🏻Genuinely Impressive Performance
👍🏻PS5 Compatibility Confirmed
👍🏻
👍🏻96 Layer TLC 3D NAND
👍🏻
👍🏻Higher Durability than WD Black & Samsung 980 Pro
👍🏻
👍🏻More affordable than the Seagate Firecuda 530
👍🏻
👍🏻Consistent 7,000MB/s on ALL Capacities
CONS
👎🏻The heatsink isn’t included and run rather hot!
👎🏻IOPS figures are lower than many PCIe4 SSDs

WD Red SN700 SSD Review – Retail Packaging

The box the WD Red SN700 SSD arrives in is exactly what you would expect., with ‘RED’ appearing throughout. as well as performance benchmarks and ratings ion show. WD absolutely NAILED IT when they introduced the colour coding system on their SSDs (IMO). Storage media is by no means an exciting or sexy subject, no matter how hard I try to make it so, with inscrutable model IDs, differences often distinguished by as little as 1-2 characters in the product number and little clarity of what makes a drive more suitable than another for purpose. So when WD introduced the Colour system for their drives, with Blue for home/basic, Black for Gamer/Pro, Green for energy-efficient, Purple for surveillance, Gold for Data Center and finally Red for NAS server use, it went an enormous way to clarify what was the ideally SSD/HDD for your the device they were going in. Your cutlery drawer has ALOT of knives inside, but have you ever tried cutting a steak with a butter knife, or spreading butter with a machete (I hope not)? Having the RIGHT tool for the job is often the first big choice you will make and Therefore you can understand why WD want to shout loud and proud about the Red SN700 SSD being NAS optimized

Like most M2 NVMe SSDs, the contents are rather low key. Unlike 2.5″ SSDs, NVMe SSDs are a great deal more barebones (given the different client hardware deployment options from tower case with active cooling, to compact NAS enclosures with modest airflow and rackmounts with enormous fan assembly). Therefore, perhaps to avoid waster, the inside of the retail box, you find the WD SN700 SSD held in a plastic outer casing.

You also find a guide to your 5 year warranty and a small amount of information about general installation recommendations, but that is about it. Here is the complete contents:

Now, I do genuinely appreciate that they want to avoid waste by including screws that people already have, heat-dissipating accessories that may not fit/be needed and more, but I am surprised they did not even include a thermal heat pad in the retail kit. It’s an incredibly small detail, but if you are installing this for the first time or even replacing an existing SSD with an upgrade to the SN700 NVMe, you are 100% going to need a thermal heat pad and it shouldn’t be assumed that you can re-use your existing one or have one with your heatsink purchase.

Indeed, with several other WD SSDs (eg the WD Black SN850) arriving with a pre-applied heatsink, I am surprised that the SN700 does not also have a heatsink enabled version as an option. These are very small criticisms and aside from heatsinks only costing you around £10-20, some NAS systems have their own smaller heatsinks you can directly apply to the controller chip etc included (most QNAP’s that have M.2 slots supply these at no additional cost). But that in term just means that this small inclusion has been missed/overlooked and I am a little surprised by that. Let’s take a closer look at the design of the WD Red SN700 and see what you are getting for your cache** in this NAS targetted NVMe SSD.

**No seriously, that is the last one…

WD Red SN700 SSD Review – Design

A closer look at the WD Red SN700 SSD does not really give away too much. The label (no need to remove it when using in a NAS etc) is pretty clear and branded, but that’s what you would expect. The 1TB SSD model featured in this model is a single-sided SSD, but as you graduate into the 2TB and 4TB model, then the NAND quantity and size changes. All five capacities of the WD SN700 series are 2280 in length, which is compatible with at least 95% of NAS systems in 2021/2022 (rare exceptions like the Drobo 5N2 etc) which support 2280 and 22110 length. Though we do need to discuss the elephant in the room a little, which is the fact that this M.2 NVMe SSD is PCIe Gen 3 x4 in architecture.

Now the fact the WD Rd SN700 is PCIe Gen 3×4 is a decision that will meet with a mixed reaction. On the one hand, practically all currently available NAS/SAN server systems up to 2021 in both the home and business market that support NVMe M.2 SSD for caching/storage max out on PCIe 3×4 (with many supporting 2×2, 3×1 or 3×2 for reasons of CPU lane restraints and chipsets). Equally, WD has been a little slow on the release of this SSD and likely at early development, PCIe 4 on a NAS system seemed a long way away. However, it can’t be ignored that several high profile NAS releases on the market in mid-late 2021 feature PCIe Gen 4 slots (not m.2), as well as flash systems arriving with U.3 support. Alongside this, their biggest rival Seagate recently launched their Ironwolf 525 PCIe 4×4 NAS SSD, to accompany their existing Ironwolf 510 PCIe 3×4 drive, which may seem overkill, but given the backwards compatibility of PCIe means that these PCIe 4 drives will still work in PCIe 3 settings. Reasons for the WD SN700 being a Gen 3 SSD could be for many reasons, ranging from better pricing, higher durability factors and making sure that product R&D is directed at value right now. Still, this is one of the earlier queries many potential WD Red SN700 buyers will have.

As mentioned, the unit for this review that was supplied by WD is a 1TB single-sided unit (2 units were used in the NAS testing later) and the back is completely clear. Let’s remove that label and take a close look at what this SSD arrives with on-board.

WD Red SN700 SSD Review – Hardware Specifications

As WD generally utilizes only in-house components and manufacturing teams on their drive media, the WD Red SN700 SSD is architecturally similar in parts to several other SSDs in their past/present portfolio, including the WD Blue NVMe and WD Black SN700 before it.

The highlights of the SN700 Hardware Specifications are:

  • Available in 250GB-500GB-1TB-2TB-4TB
  • WD NVMe Controller
  • Onboard DRAM Scaling vs Storage Capacity
  • Sandisk 3D TLC NAND
  • M.2 2280-S3-M
  • PCIe Gen 3 x4 NVMe 1.3
  • 1,750,000 MTTF
  • 0.7-1.0 DWPD (Capacity Dependant)
  • 500-5100TBW (Capacity Dependant)
  • 5yr Warranty

All fairly top tier PCIe 3×4 stuff and the durability on the drive is particularly impressive

As mentioned, the WD NVMe Controller is of in-house design and has been updated numerous times with tweaks and improvements over the years, resulting in a pretty impressive controller to largely saturate the potential 4,000MB/s of PCIe Gen 3×4, peaking at 3,430MB/s sequential Read and 3,100 Sequential Write (will go into more detail on this in the testing phase of the review below).

The storage NAND featured on the WD Red SN700 is Sandisk 3D TLC (Sandisk are owned by WD of course) and in the case of this 1TB SSD, there are two 512GB modules, so perhaps a level of over-provisioning there to keep things ticking on smoothly. The DRAM of this SSD scales with the capacity and caps out at a 4GB module for the 4TB model. All fairly standard and mildly predictable stuff. However, as mentioned earlier, the WD Red SN700 is not the only M.2 PCIe 3 x4 SSD on the market and indeed.

We will have a FULL comparison of the WD Red SN700 SSD versus the Seagate Ironwolf 510 and 525 coming next week, however here is a casual glance at how these two SSDs compare in architecture and Sequential performance for now:

Specifications Seagate IronWolf 510

Released March 2020

WD Red SN700

Released September 2021

Warranty 5yr + 3yr Rescue 5yr
MTBF/MTTF 1800000 1750000
PCIe Generation PCIe Gen 3×4 PCIe Gen 3×4
NVMe Rev NVMe 1.3 NVMe 1.3
NAND Kioxia BiCS3 64L TLC Sandisk 3D TLC
Controller PS5012-E12DC WD NVMe Controller
240/250GB ZP240NM30011$69 WDS250G1R0C$64.99
Sequential Read (Max, MB/s), 128 KB 2,450MB 3,100MB
Sequential Write (Max, MB/s), 128 KB 290MB 1,600MB
480/500GB ZP480NM30011$119 WDS500G1R0C$79.99
Sequential Read (Max, MB/s), 128 KB 2,650MB 3,430MB
Sequential Write (Max, MB/s), 128 KB 600MB 2,600MB
960/1000GB ZP960NM30011$209 WDS100G1R0C$144.99
Sequential Read (Max, MB/s), 128 KB 3,150MB 3,430MB
Sequential Write (Max, MB/s), 128 KB 1,000MB 3,000MB
1920/2000GB ZP1920NM30011$409 WDS200G1R0C$289.99
Sequential Read (Max, MB/s), 128 KB 3,150MB 3,430MB
Sequential Write (Max, MB/s), 128 KB 850MB 2,900MB
1920/2000GB N/A WDS400G1R0C$649.99
Sequential Read (Max, MB/s), 128 KB N/A 3,430MB
Sequential Write (Max, MB/s), 128 KB N/A 3,100MB

So, the big difference here (aside from the capacity difference that is the result of over-provisioning) is the peak write performance. Read performance, which forms a large part of NAS caching, is similar in the higher tiers but the WD Red SN700 holds onto that 3,000MB/s+ benchmark even at 250GB. The Write performance, which is still a big part of caching in write caching where data is committed to the SSD first to increase upload speeds and then moved to the slower HDD RAID array in the NAS, is significantly higher on the WD Red SN700 over the Seagate Ironwolf 510 SSD, despite both drives have very high durability (TBW/DWPD) for server use. So, although WD have taken longer to bring this drive to the market, it is arguably a better drive for it. Though how it compares in deeper comparison of IOPS, 4K, Pools and more will be in our comparison next week. Lets get started benchmarking the WD Red SN700 SSD on our Test Machine, a Synology and a QNAP NAS.

Testing of the WD Red SN700 SSD will be broken down into 3 main parts. The first part is testing in a single unit PC benchmark arrangement. The second test is in caching test with a Synology NAS and finally, the 3rd test will be in a QNAP NAS system as an active Storage Pool and iSCSI LUN. In the PC test, the WD Red SN700 NAS NVMe SSD was tested using multiple benchmark tools, from a cold boot, in the 2nd storage slot (i.e not the OS drive). Each test was conducted three times (full details of this are shown in the YouTube Review of the SN700 Red SSD over on NASCompares):

Test Machine:

  • Windows 10 Pro Desktop System
  • Intel i5 11400 Rocket Lake – 6-Core 2.6/4.4Ghz
  • 16GB DDR4 2666MHz Memory
  • Intel B560M mATX Motherboard
  • OS Storage, Seagate Firecuda 120 SSD
  • Test SSD connected to Secondary PCIe Gen 4×4 M.2 Slot

Using CrystalDisk, we got a good measure of the drive and verified that this PCIe Gen 3 x4 SSD was indeed using the 4×4 lane. Additionally, the temp averaged out around 44 between each test being conducted.

The first tests were conducted using the ATTO disk benchmark software. The first was a 256MB test file size and below is a breakdown of the transfer rates and IOPS. The 2nd Test was a 1GB test file and finally, the last test was with a 4GB test file. The system was given 1-minute cool downtime between tests, no screen recording software was used (remove overhead) and a heatsink was used throughout (no reboots)

ATTO Disk Benchmark Test #1

256MB File PEAK Read Throughput  = 3.19GB/s

256MB File PEAK Write Throughput = 2.90GB/s

 


 

ATTO Disk Benchmark Test #2

1GB File PEAK Read Throughput  = 3.20GB/s

1GB File PEAK Write Throughput = 2.90GB/s

 


 

ATTO Disk Benchmark Test #3

4GB File PEAK Read Throughput  = 3.20GB/s

4GB File PEAK Write Throughput = 2.90GB/s

 


 

Next, although the ATTO tests were quite good, but not what I would have hoped from this SSD, so I moved on to the Crystal Disk Mark testing to see how well it would handle our lasts barrage of tests. The first test was the 1GB file testing, which measured both sequential and random, as well as the read and write IOPS. Test were conducted on a 1GB, 4GB and 16GB Test File. I also included a mixed 70/30 read and write task to give a little bit more of a realistic balanced workload. These tests were conducted with 1-minute cooling break in between

CRYSTALDISK MARK 1GB TEST


CRYSTALDISK MARK 4GB TEST


CRYSTALDISK MARK 16GB TEST

 

Next, I switched to AS SSD benchmark. A much more thorough test through, I used 1GB, 3GB and 5GB test files. Each test includes throughput benchmarks and IOPS that are respective to the larger file sizes (important, if you are reading this and trying to compare against the reported 4K IOPS from the manufacturer).

AS SSD Benchmark Test #1

 


AS SSD Benchmark Test #2

 


AS SSD Benchmark Test #3

Ordinarily, I would introduce tests like BlackMagic and AJA into the mix here, but even a short burst of testing on an NVMe like this would over saturate the cache memory on board. Nevertheless, in the short term we still could ascertain the reported performance on 1GB, 4GB and 16GB file testing was:

1GB AJA File Test Results (Peak) = 3123MB/s Read & 2904MB/s Write

4GB AJA File Test Results (Peak) = 3121MB/s Read & 2911MB/s Write

16GB AJA File Test Results (Peak) = 3119MB/s Read & 2900MB/s Write

 

Synology NAS Drive and WD Red SN700 SSD Caching Tests

This test was conducted over a 1Gbe connection, on the DS1621+ NAS, in conjunction with two Synology HAT5400 NAS hard drives (for clarity from a full WD Red Environment). a 1TB iSCSI LUN was created on the HDD RAID array and multiple tests with a large Windows File transfer, ATTO DiskBenchmark and AS SSD was conducted in a NON-CACHE and CACHE environment, with the latter featuring the WD Red SN700 SSDs (2x 1TB in a Read and Write Cache environment). Throughput and IOPS were measured for both and compared below:

(Click to Enlarge)

 

(Click to Enlarge)

There were very clear improvements in almost all cases of using the WD Red SN700 for caching in the Synology system. Especially in write-cache areas (expected).

QNAP NAS Drive and WD Red SN700 SSD Caching Tests

In The QNAP NAS test, a TVS-872X was used and a 10Gbe shared network was used on a 10Gbe equipped machine. The WD Red SN700 SSD (2x 1TB) were placed in a RAID 1 environment as a storage pool/volume, then a 700GB iSCSI LUN was created and data was directly tested on ATTO DiskBenchmark and AJA Speed Test. NOTE – Test speeds could not full saturate the 10Gbe connection due to the PCIe 3×1 slots of the TVS-872X, a well as the iSCSI LUN being proportional to the capacity of the drive (done intentionally). Measurements for Throughput and IOPS were made. See below:

(Click to Enlarge)

 

(Click to Enlarge)

Performance differences were suitably restrained for this setup (a larger test of this SSD on a ZFS QNAP System is coming shortly featuring the WD Red SN700 and Seagate Ironwolf 510 (as well as the Ironwolf 525 if I can get that added in time!), hence why QNAP testing in this review is much shorter and in an unusual fashion. Nevertheless, the results were clear well within expected parameters and positive. Overall, the WD Red SN700 NAS SSD was certainly able to provide some solid performance, as well as potentially exceed the test figures here on a more powerful machine. Given the reported Read and Write statistics that the brand has stated publically, I think there is enough evidence here to back up those claims. IOPs were a little lower than I expected, but again, we were testing very large file types, so this would have to be taken in context and these drives are made with NAS/cache use in mind.

WD Red SN700 SSD Review – Conclusion & Verdict

There is a lot to like about the WD Red SN700 SSD. For a start, this is clearly one of the highest endurance SSDs available in their current home/SMB lineup of drives at 0.7-1.0DWPD (capacity dependant) and if you are looking for an SSD for your Synology or QNAP system as an area of write-enabled cache (or Read/Write), then you are definitely going to feel better about that lifespan. Equally, I like that WD has gone into this with a broad range of capacities to complement the varying degrees of storage potential in the average user (even 2-Bay NAS like the DS720+ or TS-251D have PCIe/M.2 expandability available by default), from as little as 250GB and all the way up to 4TB on that petite little M.2! Even when we pushed the drive in both standalone benchmarks in our test machine and in both Synology/QNAP NAS usage for caching and storage pools, the drive maintained expected performance and higher in every test. In direct comparison with it’s most comparable PCIe3 drive from competitor Seagate, the Ironwolf 510 SSD for NAS, the WD Red SN700 is a clearly higher-performing drive in read, write, durability and 4K IOPS (though the Ironwolf does have an inclusive 3-year data recovery services – a bit questionable in utility for cache recovery though). I do question the somewhat delayed arrival of a PCIe Gen 3×4 SSD for NAS as the move towards PCIe Gen 4 in NAS is starting in development, as well as the price point of this drive for NAS seemingly ignoring this transition. But if you are looking to add cache to your NAS in 2021 (as well as scaling up random performance or your storage pools in an older system), then the WD Red SN700 SSD is a solid choice and does exactly the things they claim.

PROs of the WD Red SN700 SSDs CONs of the WD Red SN700 SSDs
Good range of capacities to scale

High durability to withstand constant data recycling as cache data refreshes over time

Not limited to Cache only use if the NAS/Server allows pools and volumes

Good IOPS rating

Come out the winner over the Seagate Ironwolf 510 PCIe3 NAS SSD in almost all specs

A little Pricey for a Gen 3×4 drive in 2021/2022

A pinch overshadowed by the Seagate Ironwolf 525 at PCIe Gen4 released days apart


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    One thought on “WD Red SN700 NVMe SSD Review – Does it Deserve Your Cache?

    1. Maybe I’m just blind or glossing over it repeatedly but where are the actual NOCACHE baseline results for
      the Synology and the QNAP ?

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