SSD PCIe v SATA

[nastymatt]

I have two identical machines apart from storage, so:
mobo - Asus 170i pro gaming
cpu - i7 6700k
ram - 32gb dd4
gpu - none.

Booting both machines into the same build of Fedora (push button to login screen):
SSD - Samsung SM951 PCIe - 55s
SSD - Samsung 850 EVO SATA - 25s

Why the difference? I'd expect the PCIe SSD to be quicker than the SATA or at the very least the same, but 30s slower is a HUGE difference.

Is this to be expected or is there a BIOS setting I have missed?

 

[jimbob200521]

A stab in the dark but perhaps something to do with Fedora's implementation or support of PCIe based SSD's?

 

[Vincent]

I would also expect the PCIe SSD to be faster. You could try swapping the drives to make sure that the drives are responsible for the performance difference.

Have you compared benchmark numbers between the two drives? Sometimes to get the drives to fit a smaller form factor, manufacturers must make compromises that hurt performance.

 

[VirtualLarry]

What are the respective capacities of both drives? That affects the performance as well.

I have a pair of Skylake OCed G4400 rigs, each with 128GB Samsung SM951 AHCI PCI-E M.2 SSDs. They only score 240MB/sec for 4K QD32 random reads. I've seen SATA SSDs that score higher in reviews.

 

[dave_the_nerd]

Some motherboards and some pci-e ssds take longer to initialize during bootup. The bios init stuff is a separate process from the "read the os from disk into ram" phase of the boot process, so "power button to desktop" is a crappy benchmark. (Installing a RAID controller or a gpu would increase your boot time too.)

You're also definitely not the first person to complain about this on the forum. Seems like the samsung pcie ssds get complained about the most; either because they're more popular or because they actually take longer to init than most.

 

[shabby]

Im pretty sure the intel pcie ssd's have the same issue with boot times.

 

[h9826790]

Sounds like the computer take around 30s to initialise the PCIe adaptor + SM951 combo.

 

[nastymatt]

Ouch! Thanks for the replies.. slow initialisation is what the supplier has also said. Shame really as I really wanted it to be blistering. We are going to run some 'real world use cases' (dev builds etc) to see how much better it is up and running.

 

[PingSpike]

I thought all of the PCIe SSDs had that issue since by their very nature they would need an additional disk controller that has to initialize to function?

 

[samboy]

Interesting thread....... I've been contemplating upgrading my Windows drive to a 512GB NVMe Samsung SSD from a 256GB Samsung 830.

Given the price premium for the NVMe drives and having it significantly slow down the booting process makes the update a whole lot less attractive now!

 

[dave_the_nerd]

Interesting thread....... I've been contemplating upgrading my Windows drive to a 512GB NVMe Samsung SSD from a 256GB Samsung 830.

Given the price premium for the NVMe drives and having it significantly slow down the booting process makes the update a whole lot less attractive now!

Why? Everything else is faster - how often do you reboot your machine?

It's not like boot times are the biggest plus to having an SSD.

 

[samboy]

Why? Everything else is faster - how often do you reboot your machine?

It's not like boot times are the biggest plus to having an SSD.

Well, it's one of them......... nice having a "faster" windows update but it also reboots the machine. It is still a factor.

I've done some more reading and the IOPS numbers seem to be a little [L=Lower]http://www.overclock.net/t/1579581/official-samsung-950-pro-owners-club/20[/L] then I was expecting . On the surface, I was expecting the IOPS numbers to be a 5x improvement over the Samsung 830; but I believe I was comparing apples to oranges since the numbers I looked at were probably at a different queue depth.

It's not that this isn't fastest drive around and I'd probably choose it for a new build. It's just not compelling enough for me to upgrade from a 256GB Samsung 830. Samsung is bumping the capacity by 2x and performance by a nudge in the second half of the year and this may be more interesting for me depending on the price.

I guess I've been on the fence and slower boot times etc has swung me to wait for now.

(Not sure if I embedded the HTTP link correctly.......)