Intel PCH: performance issues

[Gandalf Corvotempesta]

Hi to all
I have a supermicro server with Intel PCH SATA controller.
I've connected 4 Intel S3610 SSDs and tried some benchmarks to see if an HBA (like the LSI 3008) is needed.

A simple:

Code:

dd if=/dev/sda of=/dev/null bs=10M count=10000 iflag=direct

run on a single disks, give me about 480MB/s

The same run on two disks at once, give me about the same speed on each disks.

The same run on all 4 disks at once, give me about 380GB/s for each disks.

380GB/s * 4 = more or less 1500MB/s

Seems that this controller is limited at 1500MB/s

Anything else that I could check ? Do you think that adding an HBA would improve performance ?

This server has 10 bays, if with 4 SSDs i've already reached the maximum bandwidth, what will happen when adding more disks up to 10? The server will just collapse, 10 SSDs at speed lower than a standard HDD speed (1500MB/s / 10 = 150MB/s)

Yes, I'm using Linux, but this is the forum with the most skilled guys about storage.

 

[Ericloewe]

The PCH is connected upstream by the equivalent of 4x PCIe lanes. That's awfully limiting.
Off the the top of my head, here's what's sharing that limited bandwidth:

• SATA
• USB
• i217/218/219 NICs and most GbE NICs, really
• Low-speed I/O
• BMC (graphics included)
• Whatever else is connected over PCIe that's not using the CPU's PCIe lanes.

 

[Gandalf Corvotempesta]

So, adding an HBA would improve performance for sure ?

 

[Ericloewe]

If you use the CPU's PCIe lanes, almost certainly.

 

[Gandalf Corvotempesta]

This is the motherboard: https://www.supermicro.nl/products/motherboard/Xeon/C600/X10DRU-i_.cfm

can you tell me if PCH is shared across the componentes you mentioned before and which PCIe lanes are used by CPU ?

 

[Ericloewe]

I can't be sure without going through the manual, but it's possible that they all are.

 

[Gandalf Corvotempesta]

I've posted you the manual. There is a link

 

[Gandalf Corvotempesta]

Supermicro told me that there are 6GBps available for each SATA port and Intel PCH is shared only with USB

The onboard SATA controller has a PCI-E 3.0 x4 DMI link (4000MB/s) direct to the CPU (which is shared with USB)


For supermicro, isn't normal to have a 1500MB/s limit