topic Re: pci-e Intel 750 Cannot Enable Write Caching in Solid State Drives (NAND)

pci-e Intel 750 Cannot Enable Write Caching

JJohn71 — Sun, 26 Jul 2015 01:30:23 GMT

I have a Rampage V Extreme motherboard with the latest chipset drivers. I also have installed the Intel 750 NVMe drivers. I cannot enable write caching in Windows 8.1 Pro. I think I disabled it while testing my PC overclocks to ensure I wouldn't get file system errors if my PC crashed but now that i'm stable I cannot enable write caching in Device Manager.

Can anyone help?

KedarWolf

Re: pci-e Intel 750 Cannot Enable Write Caching

jbenavides — Mon, 27 Jul 2015 21:56:26 GMT

Hello KedarWolf,

The configuration changes you applied to overclock the PC should not have any relation with write caching on your SSD.

The http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-750-spec.pdf Intel® Solid-State Drive 750 Series are PCIe NVMe* drives, so they are different in many ways from previous generation SSD's. Write cache on this type of drive does not work the same way as previous SSD's and it can't be configured by the user.

The Intel® Solid-State Drive 750 Series have Enhanced power-loss data protection built-in by design. This can't be disabled or enabled by the user with the options available in Windows* configuration, Intel SSD® Toolbox, or even Intel® SSD Data Center Tool.

https://downloadcenter.intel.com/search?keyword=Intel%C2%AE+SSD+750+Series Intel® Solid-State Drive 750 Downloads

Re: pci-e Intel 750 Cannot Enable Write Caching

VProk — Mon, 14 Dec 2015 17:55:03 GMT

Is there a plan to fix this? Any reason for this limitation?

I've just bought Intel 750 PCI-e myself and discovered this problem. The PCI-e is fast but caching is still faster. I have bought 64GB of RAM to allow a lot of caching. It is very disappointing that I cannot utilize it for write caching. Now I'm considering returning PCI-e card and buying a regular SSD.

Re: pci-e Intel 750 Cannot Enable Write Caching

jbenavides — Mon, 14 Dec 2015 21:37:18 GMT

Hello Vit,

It seems there may be a confusion about this, since this is not a limitation of the drive. We would need more information about the caching technology you are planning to use, but, here is some information we can provide based on your comment:

The Intel® SSD 750 Series is a PCIe drive with NVMe technology. Configuration of write caching with Intel® SSD Data Center Tool, or with the OS is a feature for ATA devices (SATA SSD's), therefore, it is not available for NVMe drives. The 750 uses new technologies to handle write and read requests even though these are not configurable by the user, this allows the drive to achieve performance that surpases the possibilities of any SATA SSD.

Handling of Reads and Writes is a lot faster with NMVe drives, however, a computer using the 750 would still benefit from additional RAM in the system.

If you obtained additional RAM planning to use a specific caching techology with software or hardware, we would advise you to contact the support team for this technology and check how the Intel® SSD 750 can be integrated to take full advantage of it in your configuration.

Re: pci-e Intel 750 Cannot Enable Write Caching

Anonymous — Tue, 15 Dec 2015 22:14:12 GMT

Are you sure that it has *EVER* been possible to toggle the cache options *FOR THIS DRIVE* in device manager?

Also I don't think your RAM would be used as disk cache in the way you think, even for common internal SATA drives.

Apparently Windows uses a portion of it for external drives when you select "Better Performance" instead of "Quick Removal", but I doubt that it is proportional to your RAM size anyway.

Re: pci-e Intel 750 Cannot Enable Write Caching

VProk — Sat, 26 Dec 2015 07:52:56 GMT

I've played a little bit with this. Wrote a small code to test speed. It writes a 3GB binary file.

static void Main(string[] args)

{ if (args.Length != 1) { return; }

var bytes = Guid.NewGuid().ToByteArray();

var watch = new Stopwatch(); using (var stream = new FileStream(args[0], FileMode.CreateNew)) { watch.Start(); for (long i = 0; i < 200000000; i++) { stream.Write(bytes, 0, bytes.Length); } watch.Stop();

}

Console.WriteLine(watch.Elapsed);

}

I intentionally wrote my own too see perf at high level as visible to apps. I also wanted to measure writing before closing stream. Closing stream could cause flushing cache and I wanted to measure without flushing cache.

I used old SATA SSD OSZ Vertex 2 60GB. It allows enabling cache on it. I tested with cache enabled and disabled and there was not difference in performance. Windows caching does not seem to make a difference in case of SSD.

But I also discovered that that extremely old SATA SSD (5+ years old) was 10% faster than Intel 750 PCIe drive. How come? Intel 750 PCIe is advertised to be 4 times faster than the fastest SATA SSD. Any suggestions how to get the advertised performance?

Re: pci-e Intel 750 Cannot Enable Write Caching

Anonymous — Sat, 26 Dec 2015 10:28:10 GMT

Vit. wrote:

That is simply not "Windows caching" that you have disabled, but write cache inside the SSD: https://gist.github.com/tomty89/ad455e0d65484973e52e gist:ad455e0d65484973e52e · GitHub

And it's natural that disabling it does not create performance impact on your/my benchmark, coz it's done on top of the filesystem.

Re: pci-e Intel 750 Cannot Enable Write Caching

VProk — Sun, 27 Dec 2015 06:42:54 GMT

Tom,

That does seem to be the case.

My question now is how do I get the promised 4x performance improvement out of Intel 750 PCIe drive? Right now it underperforms a 2 generations older SATA SSD.

Re: pci-e Intel 750 Cannot Enable Write Caching

Anonymous — Sun, 27 Dec 2015 07:53:00 GMT

How exactly is the speed anyway? Can you use some PROPER benchmark software (e.g. Crystal Disk Mark) to test it and paste the result?

Re: pci-e Intel 750 Cannot Enable Write Caching

VProk — Sun, 27 Dec 2015 08:14:27 GMT

Below are results from CrystalDiskMark. Some observations. Sequential read/write is above advertised 2500 MBps/1200 MBps. But random read/write is well below advertised 460,000 IOPS/290,000 IOPS. I need to collect results for SATA SSD using the same tool to compare.

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

CrystalDiskMark 5.1.0 x64 (C) 2007-2015 hiyohiyo Crystal Dew World : http://crystalmark.info/ http://crystalmark.info/-----------------------------------------------------------------------* MB/s = 1,000,000 bytes/s [SATA/600 = 600,000,000 bytes/s]* KB = 1000 bytes, KiB = 1024 bytes

Sequential Read (Q= 32,T= 1) : 2650.317 MB/s

Sequential Write (Q= 32,T= 1) : 1300.458 MB/s Random Read 4KiB (Q= 32,T= 1) : 611.138 MB/s [149203.6 IOPS] Random Write 4KiB (Q= 32,T= 1) : 526.938 MB/s [128647.0 IOPS] Sequential Read (T= 1) : 1590.101 MB/s Sequential Write (T= 1) : 1273.622 MB/s Random Read 4KiB (Q= 1,T= 1) : 43.865 MB/s [ 10709.2 IOPS] Random Write 4KiB (Q= 1,T= 1) : 285.223 MB/s [ 69634.5 IOPS]

Test : 1024 MiB [C: 23.5% (262.6/1117.3 GiB)] (x5) [Interval=5 sec]

Date : 2015/12/26 23:06:24 OS : Windows 10 Professional [10.0 Build 10586] (x64)

Re: pci-e Intel 750 Cannot Enable Write Caching

Anonymous — Sun, 27 Dec 2015 09:50:30 GMT

According to footnote 1 of Section 2.2 : http://www.intel.com/content/www/us/en/solid-state-drives/ssd-750-spec.html Intel® SSD 750 Series Product Specification , the performance is measured with "Queue Depth 128 (QD=32, workers=4)". I am not sure with "worker" here is equivalent to "thread" in CDM, but maybe you can try "Q=32, T=4" instead of "Q32, T=1"

See also: http://www.nvmexpress.org/blog/crystal-disk-marks-new-release-measures-true-performance-of-nvme/ NVM Express " Crystal Disk Mark's New Release Measures True Performance of NVMe

Re: pci-e Intel 750 Cannot Enable Write Caching

EEsca1 — Mon, 28 Dec 2015 03:07:25 GMT

This thread has pretty good information from a few users on what you can properly expect from Crystal Disk Mark and how to run it.

You want to use Q=32 T=8 on the random read and write tests for best comparisons to the results shown on that thread.