Samsung SM951-NVMe (256GB) PCIe SSD Review
by Kristian Vättö on June 25, 2015 9:40 AM ESTMixed Random Read/Write Performance
For full details of how we conduct our Iometer tests, please refer to this article.
In mixed performance the SM951 NVMe presents a good boost to performance over the AHCI version, although it still can't even get close to the SSD 750. This is generally an area where I would like to see improvement from Samsung and basically every SSD OEM.
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Mixed Sequential Read/Write Performance
Unfortunately the good mixed random performance doesn't translate to mixed sequential performance. The SM951 NVMe takes a quite considerable hit compared to the AHCI version, although it still offers better performance than any of the SATA 6Gbps drives on the market.
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The reason lies in the fact that performance only drops as the share of writes is increased. I suspect there might be some throttling going on, or if not then the firmware isn't properly optimized because other Samsung drives have a nice "bathtub" curve.
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bill.rookard - Thursday, June 25, 2015 - link
CentOS (Actually, RH6.5 and newer) are supposed to have in the box storage drivers for NVME. It apparently doesn't follow the same naming convention (/dev/sdx) since it doesn't utilize the SCSI protocols, but the NVME protocols.So - to check before you buy?
#modinfo nvme - should list if your kernel has built in nvme support.
if you have a drive in, check if an nvme drive is in there and is recognized
#lspci | grep nvme
SofS - Thursday, June 25, 2015 - link
Indeed, but my point was about their quality and how they compare between each other.der - Thursday, June 25, 2015 - link
10th comment!bernstein - Thursday, June 25, 2015 - link
i guess the 1tb 840 msata had either too slim margins or wasn't popular enough...still waiting for a 1tb M2 NVMe drive...
foxtrot1_1 - Thursday, June 25, 2015 - link
See you in December 2016, then.bernstein - Friday, June 26, 2015 - link
obviously i was wrong since there also is an 1tb msata 850 evo.... now i am very curious as to why samsung doesn't have a 1tb M2 ssd!!!Kristian Vättö - Friday, June 26, 2015 - link
Because all the PCIe drives use MLC NAND, which is a lower capacity die.kspirit - Thursday, June 25, 2015 - link
The connector looks the same as that on the old SATA SSDs found in most laptops. I've got a 2280 sized Intel 1500 SSD in my HP Folio (Haswell). Would this give me PCIe speeds?foxtrot1_1 - Thursday, June 25, 2015 - link
No.Metaluna - Thursday, June 25, 2015 - link
Depends on whether HP hooked up the PCIe lanes on their M.2 connector, which I wouldn't assume without checking into it. The BIOS also needs to have NVMe support. In the most common configurations (i.e. the "B" and "M" keyings), M.2 is required to carry both SATA and 2-4 PCIe lanes, but some motherboard vendors routinely violate this and leave out one or the other. Asus drops the SATA on some of their higher-end Z97 motherboards, for example, so you can't rule out that someone else may have made the opposite tradeoff.