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Guru
Posts: 1,802
Registered: ‎04-20-2008
Location: US
Views: 3,344
Message 1 of 10

Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

I ran a performance test of the RAID1 (Samsung 951 PCIe-NVMe 512GB) and the Samsung 850 Pro 1TB which are both installed in my P70 (signature below). Here are the results:

 

Samsung 951 PCIe-NVMe 512GB RAID1

 

P70_RAID1_PCIe_NVMe.JPG

 

 

Samsung 850 Pro 1TB

 

P70_Samsung_850_Pro.JPG


P70 XEON 1505, BIOS 2.30, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, 2x Samsung 850 Pro 1TB SSD. EM7455 WWAN
P1. BIOS 1.22,Xeon Processor, 32GB, PM981 1TB x 2, RAID 1
T470s, 16GB RAM, BIOS 1.10, i7-7500, WQHD display, 512GB PM961 PCIe NVMe SSD
SeniorGuru
Posts: 2,271
Registered: ‎06-13-2013
Location: US
Views: 3,297
Message 2 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

Just for comparison, here is my own P70 with 2 x 512GB 950 Pro (non-RAID) NVMe and also with 850 Pro SSD.

 

(1) Timings for NVMe0 (non-RAID):

 

NVMe (non-RAID)

 

(2) Timings for 850 Pro SSD

 

850 Pro

 

(3) Just wanted to point out that Samsung Magician supports "rapid mode" for one SSD (even if more than one SSD is present).  And it does not support "rapid mode" for NVMe.  But that means it could support "rapid mode" for the 850 Pro in my machine, and in fact I have enabled "rapid mode" for my 850 Pro.

 

Rapid mode utilizes unused and thus available RAM in the machine as a cache for the SSD, improving benchmark numbers dramatically.

 

Here are the numbers for my 850 Pro with "rapid mode" enabled.

 

850 Pro (rapid mode enabled)

 

 

 

 

p600
Broadband 3G
Posts: 484
Registered: ‎10-03-2011
Location: CA
Views: 3,263
Message 3 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

I wonder what's the practical use of "rapid" mode other than getting benchmark numbers. OS has its own caching, in the unused RAM, and there is certainly increased risk of data loss.

 

Can't think of any kind of processing, outside of copying files, that requires so much data, and so little CPU involvement, that laptop CPU can process sustained even 500MB/sec of input data? Even Bitlocker encryption (with hardware processor support of AES-NI) causes high CPU when writing to 950Pro at ~2GB/second.

Guru
Posts: 1,802
Registered: ‎04-20-2008
Location: US
Views: 3,256
Message 4 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

Agreed! The Samsung Rapid Mode looks good in benchmarks, but not in practical use. Reviews that have been published in different sites have shown how rapidly things tail off once the RAM cache has been depleted. In fact, in some cases the overall performance is worse than running without the software. I've personally experienced corruption on my Pro 850 SSD that experienced a laptop shutdown that forced me to eventually reimage the system (cleaned the drive and reimaged with an existing backup).

 

YMMV


P70 XEON 1505, BIOS 2.30, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, 2x Samsung 850 Pro 1TB SSD. EM7455 WWAN
P1. BIOS 1.22,Xeon Processor, 32GB, PM981 1TB x 2, RAID 1
T470s, 16GB RAM, BIOS 1.10, i7-7500, WQHD display, 512GB PM961 PCIe NVMe SSD
SeniorGuru
Posts: 2,271
Registered: ‎06-13-2013
Location: US
Views: 3,203
Message 5 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

I guess there have been a number of articles covering this topic over the past few years, since Samung Magician and rapid mode has been available.

 

This particular article in TheSSDReveiw concludes that some of the aspects of the technology which were evaluated and measured showed no significant difference.  No harm, no foul, but no great benefit either.

 

However the final paragraphs, reflecting on the use of PCMark 8 measurements, argue that there is a significant reduction in "latency" due to rapid mode.

 

---------------------------------------------------------------------------------------------------------

 

"In testing, Samsung’s synthetic benchmark showed a night and day difference in performance with RAPID mode enabled, but it didn’t feel like it in our perceptible use of the system when enabled. To test out why, we benchmarked our startup time and application load times. As a result, startup was slower, but it was so minute a difference that it shouldn’t cause anyone to lose any sleep over it. Application load times also proved to gain no benefit, however, we were testing only the programs themselves at first. After testing some work files, it followed a similar trend. Recently accessed files should prove to have a faster retrieval speed after reboots, however they did not. Our testing methodology proved RAPID did not afford any benefit outside of Windows default caching behavior in these instances. It wasn’t until our workload testing was done that we saw a performance increase.

 

"Our final testing with PCMark 8 gave us some better insight on how RAPID can improve a system’s performance. Average latency was cut in half and the total latency was cut down by more than that. The average bandwidth results proved something a bit different at first, steady state performance showed to be lower, but when in the recovery phase, average bandwidth shot up to speeds nearly triple to that of the system with RAPID disabled. Based upon our results, we can tell that RAPID actually does work and it really can significantly speed up real world performance.

 

"So in all, RAPID does indeed increase a system’s performance. In day to day usage start up and opening application times will not be affected, however, when it comes to actually working on projects, RAPID will help to speed things up."

 

-------------------------------------------------------------------------------------------------------------------------

 

Note that rapid mode does NOT support NVMe, which of course is where the OS lives in our P70's which now have 3-4 SSD devices in them.  In fact theonly SSD in my P70 for which rapid mode can even be enabled is the 850 Pro SATA3 SSD now living in the primary drive bay where it replaced the original factory 500GB HDD spinner which came from Lenovo in my original purchase.

 

So, with the 512GB 850 Pro being a "data" drive and not an OS drive, and in my case containing nothing but general storage, image files, audio/video and other multimedia files, and used for carry-around backup and image files, I wonder if the READ/WRITE performance improvements shown in pure benchmark measurements might not actually show up much more visibly than on an OS drive, simply because of the very different type of usage the 850 Pro will be getting in its real world environment.

 

Here's the original Samsung white paper on Rapid Mode from 2013, when they originally brought it out with Magician 4.2.

 

Here's an ExtremeTech review, including discussion of Rapid mode.  They're impressed.

 

Note that the "risk" of using memory as cache and thus committing writes to volatile DRAM, well, in my own 3-year experience of using an SSD on my W530 I have NEVER had any failure of any kind.  There is no such thing as a "power outage" (since laptops have batteries that take over instantly if wall power is lost), and I've never had any corruption on permanent storage that required me to restore a 100% perfect system image backup.  I've never lost any data, and I've never lost Windows.

 

In other words I consider any theoretical "risk" of using RAM for cache to be ZERO.  I'll take whatever performance benefits it provides, and thank Samsung for it.

 

Of course that's just me and my opinion.

Oa421AmlCQ
Punch Card
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Location: Brooklyn
Views: 3,197
Message 6 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB


@harrisb wrote:

I ran a performance test of the RAID1 (Samsung 951 PCIe-NVMe 512GB) and the Samsung 850 Pro 1TB which are both installed in my P70 (signature below). Here are the results:

 

Samsung 951 PCIe-NVMe 512GB RAID1


 

How does it look in raid 0?

Guru
Posts: 1,802
Registered: ‎04-20-2008
Location: US
Views: 3,188
Message 7 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

 

@Oa421AmlCQ

 

The OS is setup in the RAID1 array. I'm not going to experiment with the configuration at this point.

 

 

@ 

 

I'm satisfied with the performance of the 850 Pro as currently configured which is located in the first HDD position and is used only for data storage. Thanks for your earlier response.


P70 XEON 1505, BIOS 2.30, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, 2x Samsung 850 Pro 1TB SSD. EM7455 WWAN
P1. BIOS 1.22,Xeon Processor, 32GB, PM981 1TB x 2, RAID 1
T470s, 16GB RAM, BIOS 1.10, i7-7500, WQHD display, 512GB PM961 PCIe NVMe SSD
Guru
Posts: 1,802
Registered: ‎04-20-2008
Location: US
Views: 3,177
Message 8 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

Note that the "risk" of using memory as cache and thus committing writes to volatile DRAM, well, in my own 3-year experience of using an SSD on my W530 I have NEVER had any failure of any kind.  There is no such thing as a "power outage" (since laptops have batteries that take over instantly if wall power is lost), and I've never had any corruption on permanent storage that required me to restore a 100% perfect system image backup.  I've never lost any data, and I've never lost Windows.

 

In other words I consider any theoretical "risk" of using RAM for cache to be ZERO.  I'll take whatever performance benefits it provides, and thank Samsung for it.

--------------------------------------------------------------------------------------------------------------------------------------------------------

 

You've obviously never experienced a system board issue with your system. Lucky you. My W520 no longer has a low-power mode (fuse has opened on the system board) so shutting down the system sometimes is not as graceful as one might expect. Also, there can be issues with a hung application that requires a forced "power off" via the power button while the drive is still be accessed. There can be even more reasons than that. 

 


P70 XEON 1505, BIOS 2.30, UHD 4k Display, 64GB non-ECC RAM, M3000M NVIDIA GPU, RAID 1 512GB Samsung 951 PCIe-NVMe SSD x 2, 2x Samsung 850 Pro 1TB SSD. EM7455 WWAN
P1. BIOS 1.22,Xeon Processor, 32GB, PM981 1TB x 2, RAID 1
T470s, 16GB RAM, BIOS 1.10, i7-7500, WQHD display, 512GB PM961 PCIe NVMe SSD
p600
Broadband 3G
Posts: 484
Registered: ‎10-03-2011
Location: CA
Views: 3,176
Message 9 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB


@DSperber wrote:

 

In other words I consider any theoretical "risk" of using RAM for cache to be ZERO.  I'll take whatever performance benefits it provides, and thank Samsung for it.


It's not ZERO, but is quite low. And by default Windows (and most other systems) will enable write buffering for non-removable drives, unless you uncheck the box in device manager . If other device drivers are reliable, you're not doing any low level system development, and "blue screens" are rare, this works fairly well. And it respects preferences of the applications (which may request, like SQL server, "write this data so it actually hits the drive"), even though these are most of the time safe to ignore.

 

I'm more after WHAT "performance benefits it provides" in practice. What do you do, so you see the difference casually, where something that used to take a minute, now takes 40 seconds, or smth like that. Outside of copying files and running syntetic benchmarks.

 

Because in casual testing, running lots of VMs etc, I hardly see any difference between any "normal" SATA III SSD and NVMe. 500MB/s, 2GB/sec, 5GB/sec. It's all getting CPU bound much sooner than it hits the bottleneck of SATA III SSD bandwidth.  

badhabit_wb
Token Ring
Posts: 170
Registered: ‎10-26-2008
Location: louisburg, nc
Views: 2,984
Message 10 of 10

Re: Comparison between Samsung 951 PCIe-NVMe 512gb RAID1 vs Samsung 850 Pro 1TB

I had the same machine in raid 0. The read speeds were basically the same but the write speeds increased into the 2700's. Not sure what was limiting the read speed but I started a thread on it.

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