I have a server that includes an AOC-SASLP-MV8 and has been rock solid. I'm considering making some upgrades (CPU etc) and am wondering if it would be worth upgrading my PCI-E x4 card to an x8 card. Would I see much performance improvement? My current average parity check speed is 90MB/s.

 

It will depend on the other hardware and disks used, 90MB/s is not bad and may already be close to max speed if you're using one or more older and slower disks.

Ok, thanks. I guess that's good. I saw that you posted a write speed test script on another thread. Would running that on my drives help me understand the bottleneck?

Use this instead:

 

 

This will show each disk speed in a nice graphical display, parity check can't be faster than your slowest disk at any point, but if it's slower it means there's a bus/controller or other bottleneck somewhere.

 

I'll give that a try. Thanks again!

Just wanted to follow up with what I've learned in case it can help anyone else.

 

It looks like the AOC-SASLP-MV8 supports 300MB/s per channel (8 channels). 6TB WD drives support sustained read/write speeds in the 175-225 MB/s range (Blues are slower than Reds). My testing with the diskspeed script shows results that are in line with this for my 6TB drives (slower for my older/smaller drives). So the card doesn't seem to be a bottleneck at all.

 

So no reason to upgrade until sustained drive speeds exceeds 300MB/s. If you want to connect SSDs to a SAS/SATA controller then you'd probably want something faster, but I'd recommend using the motherboard SATA ports for those if at all possible. 

It will support close to 300MB/s per channel, but not if you use them all at the same time, maximum real world speed with 8 discs is 80MB/s.

 

 

Ah, ok. Got it. That makes sense. It seems that the nature of my files on Unraid means that I'm typically only accessing one or two drives at a time. Or am I missing something? It just depends on the number of users and the way files are split across drives right?

 

Your post has TONS of great info! Thanks for sharing that.

 

It looks like the 8 x 80MB/s limitation must be based on the card itself and not the x4 bus speed, because it's not approaching the 1000MB/s limit. Correct?

Correct, no controller hits the maximum theoretical speed but the saslp falls shorter than normal, still you shouldn't hit any limits during normal unRAID utilization, you can during parity checks, disk rebuilds and writes only if using turbo write.

 

 

Cool. Thanks again for all of the info.

Almost certainly, you should put your 3 x 6TB drives and the 3TB on the 4 Sata ports on the motherboard. By the way, that is one strange motherboard -- but, as they say, "Don't look a gift horse in the mouth." Right, shooga?

 

["Strange", as in PCIe v1 and USB3, and more rs-232 ports than disk ports; but it does have 2 x GbE LANs.]

 

--UhClem

 

Edited March 18, 20179 yr by UhClem

Yeah, it's strange indeed. The power connection means that the drives aren't connect to the power switch at all, they always get power.

 

That MB is part of what has me considering an upgrade. That plus the tempting new Ryzen CPUs. But I'm having second thoughts now because this server has been rock solid. And you're right about that gift horse, but finding a mobile CPU cooler that I like sure was hard

 

I have my 6TB drives and SSD on the MB SATA ports, but thanks for pointing that out.

 

BTW, I'm glad you found the info about my server, but how did you find it? Just old posts? I'd like to share it and people used to put that info in their signatures here on the forum, but it seems like that stopped with the new forum software. I don't see an obvious place for it in my profile either.

 

Edit: Well now I see that there is a setting that you have to turn on to show people's signatures. Guess you probably had that turned on... (and my old sig is still there, but now it's in Account Settings rather than Profile)

Edited March 18, 20179 yr by shooga

42 minutes ago, shooga said:

BTW, I'm glad you found the info about my server, but how did you find it?

You put it in your signature. But I bet that you thought signatures stopped working since you weren't seeing them. You have to enable the viewing of signatures, as a reader. Go: "3 horiz bars" (in upper right of the forum window [not your browser]) -> Account -> Account Settings -> Signature ; then Enable "View Signatures".

 

[ To get the details I wanted, to provide you advice, I looked at the specs for your mobo (model# in your sig). It looked "weird" to me, but what do I know--I did my most recent (and probably last) build in '08. So, figuring everyone else probably knew all about it, I GOOG'd for it, filtering for this forum. And, there was the back-story. ]

 

Since your sig says your 850 EVO is mSATA, is it not using the mobo's "mini-sata"? Or, does other weirdness preclude that? If it can use it, do so; and put the 3TB in that (now-free) Sata port. The goal is to offload the bandwidth "stress" from the MV8. I'm betting that the QM87 chipset (on the mobo; supplying the satas, etc.) can handle at least 700 MB/s.

 

--UhClem   "Are we having fun yet?"