4 Drive SSD RAID 0 Mac Pro 5,1

riggieri

macrumors newbie
Original poster
Apr 30, 2012
27
5
Hey All

I am building a MAC Pro 5,1 with a 4 Drive SSD Raid in the drive bays. I am only seeing speeds around 600 MB/s, when I am expecting 1-1.2GB/s. Is this a limitation of the internal SATA controller?
 
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leon771

macrumors regular
Sep 17, 2011
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You've hit the SATAII limit. Better off building raid that uses a pcie controller and. It the Apple backplane.

Should use pcie flash instead of sata based 2.5" drives or blades if raw speed is what you want.
 

riggieri

macrumors newbie
Original poster
Apr 30, 2012
27
5
You've hit the SATAII limit. Better off building raid that uses a pcie controller and. It the Apple backplane.

Should use pcie flash instead of sata based 2.5" drives or blades if raw speed is what you want.
SATA II LIMIT IS 3gb per channel and this is over four channels. I guess the apple backplane and controller are hitting about maximum on this anyways.
 

h9826790

macrumors G5
Apr 3, 2014
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Hong Kong
1) Your SSD may have only 150MB/s, some smaller (e.g. 250G SATA SSD) only has this write speed. Therefore, 4x150=600

2) For some better SATA SSD, may hit the 250MB/s read/write speed bottleneck due to SATA 2 limitation. So, the best you can achieve is about 1000MB/s, no way to achieve 1.2GB/s

For high speed storage, simply get a PCIe SSD is a better way, 4 SSD in RAID 0 means 4x the failure rate, and the best you can achieve is just about 50% of a single PCIe SSD can do. So why take the risk but not go for simpler setup which have better performance?
 

Machines

macrumors 6502
Jan 23, 2015
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Fox River Valley , Illinois
Hey All

I am building a MAC Pro 5,1 with a 4 Drive SSD Raid in the drive bays. I am only seeing speeds around 600 MB/s, when I am expecting 1-1.2GB/s. Is this a limitation of the internal SATA controller?
cMP have an aggregate SATA backplane upper throughput limit of about 650 MB/s , across the four drive connectors . It's host computer chipset related , not drive related per se . That's why it doesn't make much performance difference between using SSD and HDD in this situation .

Solution is to grab a mini SAS PCIe card and internally mount the SSDs in your Mac Pro . OWC has a Newer Technology card .

http://eshop.macsales.com/item/NewerTech/MXPRMS6G1E1I/

maxpower_minisas_1e1i.jpg
 
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Squuiid

macrumors 68000
Oct 31, 2006
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cMP have an aggregate SATA backplane upper throughput limit of about 650 MB/s , across the four drive connectors . It's host computer chipset related , not drive related per se . That's why it doesn't make much performance difference between using SSD and HDD in this situation .

Solution is to grab a mini SAS PCIe card and internally mount the SSDs in your Mac Pro . OWC has a Newer Technology card .

http://eshop.macsales.com/item/NewerTech/MXPRMS6G1E1I/

View attachment 620180
Yep, and use a MaxConnect to connect the drives using the existing SATA power in the backplane.
http://www.maxupgrades.com/istore/index.cfm?fuseaction=category.display&category_ID=351
 

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macrumors 6502
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Squuiid

macrumors 68000
Oct 31, 2006
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"Yep, and use a MaxConnect to connect the drives using the existing SATA power in the backplane."

Maxupgrades has a confusing website , but I think the OP's situation requires this kit to mount four SSDs in his Nehalem cMP :

http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_ID=189&ParentCat=351

View attachment 620183

HBA card is not included in the price - it's just for the special sled adapters (and I assume the fan out mini SAS cable) for four SSD .
Depends if the OP needs a 12Gbps or 6Gbps fan out cable ;)
Your link is for a 6Gbps cable.
And yes, their website is HORRIBLE.
 

Machines

macrumors 6502
Jan 23, 2015
426
89
Fox River Valley , Illinois
Depends if the OP needs a 12Gbps or 6Gbps fan out cable ;)
Your link is for a 6Gbps cable.
And yes, their website is HORRIBLE.

The OWC Newer Technology RAID card I linked is 6 Gb/s , so that would be the limiting factor .

And the OP's SSDs are likely non-enterprise grade 6 Gb/s SATA .

Areca does have a 12 Gb/s mini SAS RAID card ( ARC-1883LP ) compatible with OS X 10.11 El Capitan , with an internal connector :

http://www.areca.com.tw/products/1883.htm

Things do get more expensive with everything at 12 Gb/s , of course .

The throughput he desires (around 1100 MB/s) can be achieved with three x 6 Gb/s SSD in the array , Since the OWC Newer Technology card is not bootable in OS X , that would leave one SATA backplane available for a separate drive with an OS X install .
 
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throAU

macrumors 604
Feb 13, 2012
6,544
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Perth, Western Australia
Possibly not enough PCIe lanes allocated to the on-board SATA controller(s) to run all channels flat out at the same time.

The classic mac pro was designed in a time where SSD was rare and super expensive, it wasn't really expected to deal with devices that can saturate the SATA bus to the extent that SSDs can. When the older Mac Pro came out allocating 1:1 bandwidth in terms of PCIe -> max SATA channel speed would have been a waste.

Can maybe get around this with a PCIe card.
 

Machines

macrumors 6502
Jan 23, 2015
426
89
Fox River Valley , Illinois
Possibly not enough PCIe lanes allocated to the on-board SATA controller(s) to run all channels flat out at the same time.

The classic mac pro was designed in a time where SSD was rare and super expensive, it wasn't really expected to deal with devices that can saturate the SATA bus to the extent that SSDs can. When the older Mac Pro came out allocating 1:1 bandwidth in terms of PCIe -> max SATA channel speed would have been a waste.

Can maybe get around this with a PCIe card.
I just happened to think that for very high end bandwidth requirements , installing a mini SAS RAID card would require PCIe Slot 2 installation in a Nehalem cMP . A lot of these cards require 8 lanes electrical and at PCIe Rev 2 specs this would provide 8 x 500 MB/s ( = 4 GB/s) performance , minus any overhead .
 

VaZ

macrumors regular
Aug 31, 2012
214
67
So say i installed 6 HDD in all 6 sata ports and RAID 0, should i hit 1GB/sec?
 

tsialex

macrumors 604
Jun 13, 2016
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As per the manual 0.3GB/s x6 = 1.8GB/s.
And we know the real world speed is about 250MB/s per SATA port. So. ~250MB/s x6 = ~1500MB/s
View attachment 889978
It's more complicated than that since Southbridge has a x4 connection for everything, so it's seriously limited. People tested this in the past and even if you RAID all 6-SATA ports, you can't get over 550~600MB/s. BTW, 4 SATA ports or 6 SATA ports get the same results.

Apple new this from the start, AppleRAID card is connected directly to PCIe.

Everything = SATA/SAS, USB, Ethernet, Wi-Fi, Firewire, SMC, Audio.
 
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h9826790

macrumors G5
Apr 3, 2014
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It's more complicated than that since Southbridge has a x4 connection for everything, so it's seriously limited. People tested this in the past and even if you RAID all 6-SATA ports, you can't get over 550~600MB/s. BTW, 4 SATA ports or 6 SATA ports get the same results.

Apple new this from the start, AppleRAID card is connected directly to PCIe.

Everything = SATA/SAS, USB, Ethernet, Wi-Fi, Firewire, SMC, Audio.
That's true, the final possible speed depends on the wifi, ethernet, audio, bluetooth.... etc.

It's impossible to achieve full 1500MB/s in real world.

But I am not sure what's the actual limit. I think someone achieved 750MB/s before, but not really sure.

In fact, I wonder what will happen if someone do the disk speed test (e.g. BlackMagic), then shutdown / disable those things attach to the southbridge one by one :rolleyes:
 
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tsialex

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Jun 13, 2016
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That's true, the final possible speed depends on the wifi, ethernet, audio, bluetooth.... etc.

It's impossible to achieve full 1500MB/s in real world.

But I am not sure what's the actual limit. I think someone achieved 750MB/s before, but not really sure.

In fact, I wonder what will happen if someone do the disk speed test (e.g. BlackMagic), then shutdown / disable those things attach to the southbridge one by one :rolleyes:
In the past someone tested this, removing the AirPort Extreme, the only thing that you can really be removed and didn't change anything. There are even more things connected than I listed, like GPIO, I2C, RTC, LPC, APIC and others, I previously listed the bandwidth hogs.

I can be wrong, but I remember that sustained speeds are around 550MB/s mark with a little more for peaks, but never saw 750MB/s. Remember that the IC10 south bridge is from third quarter of 2008, at the time the best HDDs were around the 100MB/s mark.
 

flygbuss

macrumors 6502a
Jul 22, 2018
657
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Stockholm, Sweden
In the past someone tested this, removing the AirPort Extreme, the only thing that you can really be removed and didn't change anything. There are even more things connected than I listed, like GPIO, I2C, RTC, LPC, APIC and others, I previously listed the bandwidth hogs.

I can be wrong, but I remember that sustained speeds are around 550MB/s mark with a little more for peaks, but never saw 750MB/s. Remember that the IC10 south bridge is from third quarter of 2008, at the time the best HDDs were around the 100MB/s mark.
I get between 630 and 680 MB/s with three Samsung 860 EVO in the cMP SATA slots.
 
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