Bandwidth on AMD 880G+SB850

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Glock24

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May 13, 2019
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This is not enterprise hardware, so maybe won't get much attention. But here I go.

I needed to test a lot of SSDs I bought in the last months, my main computer is a laptop and my server has no spare bays, so I unearthed an old computer that has 6 SATA 6Gbps ports to test my disks. The motherboard is an Asus M5A88-M with an FX-6600 CPU, I got this board long as it supported ECC RAM and 32GB RAM.

I populated all SATA ports and started a full read test, but I noticed the read speeds were very low. I stopped the tests and started one drive at a time. With only one SSD I'm able to saturate the SATA interface, but with two drives bandwidth is capped at around 350MB/s per port. With all 6 drives bandwidth per port is around 120MB/s. The available bandwidth for the SATA controller (or southbridge) seems to be a little over 700MB/s.

Searching a bit the available bandwidth for the SB850 is "2GB/s" which I guess is GigaBytes/s, as 2 GigaBits/s would be 250MB/s.

890-block-diagram.jpg

There are no USB3 devices using bandwidth and no activity on the GbE network, so no other devices are eating up the bandwidth. Any ideas what could be limiting the SATA controller bandwidth? Or down anyone know what the real 880G <-> SB850 bandwidth is?
 

RolloZ170

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Apr 24, 2016
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maybe you have configured the SB850 SATA ports still to IDE mode(BIOS) ?
the SB850 has only 2x IDE controllers. it looks to me there are not 6 complete controllers, just 6 channels.
 

Glock24

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May 13, 2019
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All ports are configured as AHCI, only ports 5 and 6 can be configured as IDE.

You may be right about it being a single controller with 6 ports, 6Gbps is 750MB/s.
 

RolloZ170

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Apr 24, 2016
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A-Link Express III interface to Northbridges
 1-, 2-, or 4-lane A-Link Express III interface

or the mobo uses not all 4 lanes ?
 

Glock24

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May 13, 2019
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Yep, that's another possibility, Asus may have skimped on the SB-NB link as nobody at that time would saturate all SATA ports.
 

MichalPL

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Feb 10, 2019
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Confirming that AM3 (plus six core CPU ~4.5GHz) is super slow <- have similar experience 5x Samsung SATA HDD, max ~150MB/s (same HDDs later in faster computer (Xeon 1650 v2 and TR 1950X) was doing ~210MB/s). Yes AM3 is trash and similar to older Core 2 Duo/Quad platform ;)

From my experience SATA 6gbps is max ~550MB/s and things like this (connected to USB 3.0) can achieve it (or super close), even in laptop:
 

MichalPL

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Feb 10, 2019
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It depend (only) of the USB controller inside laptop/motherboard.

when your controller is USB Gen 3.2 yes of course, USB 3.1 probably yes, if older - it depend (probably no).

If you need speed on all at the same time "for cheap":
LSI 9217 (8 SATA ports/ 2x SAS) connected to PCIe 3.0 x8 directly to CPU (for example $15 Xeon E5 1620 or i7 3770k or similar) can do 4.4GB/s (tested by me on slightly overclocked Xeon E5 1650 v2).
 
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MichalPL

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Feb 10, 2019
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yes :) USB HUB is good place to show it.

conclusion this is cheap and fast, saturate all 8 SATA ports at the same time: LSI 9217-8I 6Gbs SAS PCI-E 3.0 HBA FW: P20 IT Mode For ZFS FreeNAS unRAID US | eBay

First (say cheapest) CPU that bottleneck on SSD's/NVMe practically didn't exist is Xeon E5 (if I remember correctly achieved ~25GB/s on E5 v2 and ~28GB/s E7 v2) - of course too slow single core to decode on 1 thread ZFS at the same time.
 

Glock24

Active Member
May 13, 2019
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Confirming that AM3 (plus six core CPU ~4.5GHz) is super slow <- have similar experience 5x Samsung SATA HDD, max ~150MB/s (same HDDs later in faster computer (Xeon 1650 v2 and TR 1950X) was doing ~210MB/s). Yes AM3 is trash and similar to older Core 2 Duo/Quad platform ;)

From my experience SATA 6gbps is max ~550MB/s and things like this (connected to USB 3.0) can achieve it (or super close), even in laptop:
AMD conauner platforms had better features than Intel platforms at the time, eg. SATA 6 & USB3. CPUs after Stars architecture were a power hog and performance was really bad compared to all Intel platforms until Ryzen arrived.

With this board I can get 500-580MB/s (depending on the ssd) on any SATA port, just not all ports at the same time. With the USB ports I can easily get 350MB/s, haven't tested my newer enclosures with this board.

yes :) USB HUB is good place to show it.

conclusion this is cheap and fast, saturate all 8 SATA ports at the same time: LSI 9217-8I 6Gbs SAS PCI-E 3.0 HBA FW: P20 IT Mode For ZFS FreeNAS unRAID US | eBay

First (say cheapest) CPU that bottleneck on SSD's/NVMe practically didn't exist is Xeon E5 (if I remember correctly achieved ~25GB/s on E5 v2 and ~28GB/s E7 v2) - of course too slow single core to decode on 1 thread ZFS at the same time.
E5/E7 is not a consumer platform, you are comparing apples to rockets here.
 

MichalPL

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Feb 10, 2019
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AMD conauner platforms had better features than Intel platforms at the time, eg. SATA 6 & USB3. CPUs after Stars architecture were a power hog and performance was really bad compared to all Intel platforms until Ryzen arrived.
True, I select it as a platform for NAS (5x 5TB) and 1GbE <- was fast enough for Samba

With this board I can get 500-580MB/s (depending on the ssd) on any SATA port, just not all ports at the same time. With the USB ports I can easily get 350MB/s, haven't tested my newer enclosures with this board.
If I remember correctly same on my board (just not all ports at the same time).
Also motherboards for Xeon and first Threadrippers have same issue, just limit was higher (I don't remember, but probably around 1.5 maybe 2GB/s).

PCIe controllers of course bypass motherboard (chipset) limits.

E5/E7 is not a consumer platform, you are comparing apples to rockets here.
i7 3770k with more cores, and much more PCIe lanes, better cooling - but yes
old Xeons E5 v2/v3 was rockets for ~6 years (until Ryzen5000/TR5000).


performance was really bad compared to all Intel platforms until Ryzen arrived
In my opinion...
Zen2 was first fast architecture, Zen 3 was amazing, Zen 4 too.
Zen and Zen+ was still not able to compete with Xeons from 2013 (ok maybe TR2000 with 32 cores ;) )