Looking for thoughts - SAS 2308 + SSD = Really bad write performance

[pjkenned]

Hi All,

Been working a bit this weekend on a new rig. Fairly decent specs:
2x Intel Xeon E5-2690
32GB DDR3 1333MHz (will be replaced by more 1600MHz RAM once setup is complete, just running low on RAM at the moment)
Supermicro X9DR7-LN4F motherboard with onboard LSI SAS 2308 in IR mode (stock)

The basic issue is that write speeds are bordering on abysmal, and I am trying to figure out why. A bit tired so looking for other suggestions since I feel like this may be one where there is a simple answer that I'm just missing.

For the longer version I posted on the LSI SAS 2308 SSD performance issues (http://forums.servethehome.com/showthread.php?1040-Interesting-Windows-Server-2012-LSI-SAS2308-Controller-Results) here. Going to provide a summary for folks.

OS/ Driver/ Firmware Configurations
1. OSes: Windows Server 2012 Datacenter & Windows 7 Ultimate x64
2. Firmware: IR and IT mode 14.x generation (both OSes)
3. Drivers: 2.0.55.x and 2.0.58.x series.
4. 240-256GB SSDs (each in single drive configs) - Samsung 840 Pro, Samsung 830, OCZ Vertex 4, SanDisk Extreme 240GB, Kingston V+200
5. Write cache setting in Windows on and off for each drive.

I have verified that the card is getting an x8 PCIe 3.0 link. I have also verified that the drives are negotiating 6.0gbps links.

What does write performance look like? Examples are not so good.

Here is a Samsung 840 Pro 256GB (write cache on):
http://www.servethehome.com/wp-content/uploads/2012/11/Samsung-840-Pro-256GB-Anvil-Storage-Utilities-v2.00.55.84.png
Write cache off:
http://www.servethehome.com/wp-content/uploads/2012/11/Samsung-840-Pro-256GB-Anvil-Storage-Utilities-write-cache-off.png

SanDisk Extreme 240GB (write cache on in Windows Server 2012)
http://www.servethehome.com/wp-content/uploads/2012/11/SanDisk-Extreme-240GB-Anvil-Storage-Utilities-v2.00.55.84.png
Turning off write cache helped a lot:
http://www.servethehome.com/wp-content/uploads/2012/11/SanDisk-Extreme-240GB-Anvil-Storage-Utilities-write-cache-off.png

Results looked very similar to those. The Vertex 4 was well below Intel PCH speeds but stayed consistent. SandForce speeds up with write cache off, but still look slow. Samsung speeds are just bad all around.

Any thoughts as to what is causing this?

[pjkenned]

Sorry for replying to my own thread... but just found something interesting. Anvil's, ATTO and AS SSD all showed greatly reduced performance. I went back to IOMeter and started doing 4K 100% random write 4 worker. 16K IOPS on the Samsung 830.

[Nizzen]

Xtreme Storage, I can not see it :p

[pjkenned]

Culprit seems to be that you need to click the write-through check box using the LSI SAS 2308 controllers with Anvil's. IOMeter seems not to be bound by this. We had someone confirm the same behavior on their LSI + SSD setup.