Topic Title: "Enable write caching on the device" VS RAIDXpert
Topic Summary: Is this what is meant to be happening ?
Created On: 01/30/2013 10:58 AM
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 01/30/2013 10:58 AM
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mongo
Peon

Posts: 4
Joined: 01/30/2013

Setup

Windows 7 SP1
Latest RAID Drivers
Latest motherboard bios (Crosshair V Formula)
RAID 0 array setup using RAIDXpert

Device Manager

Disk drives --> AMD 2+0 Strip/Raid0 --> Double click -->  Enable write caching on the device

RAIDXpert

Logical Drive View --> Settings

Now..

In Device Manager "Enable write caching on the device" is not checked by default.

This value though can be changed via RAIDXpert.

This is what happens

If we check the "No Cache" option and apply the setting this will change the "Enable write caching on the device" setting in Device Manager to be checked.

If we check either the "Read Cache" or "Read Ahead" then the "Enable write caching on the device" in Device Manager will be unchecked.

Is this what is meant to be happening ?

Using RAIDXpert, "No Cache" performance using AS SSD with 4K writes is arnd 60 MB/s, using "Read Ahead" performance is arnd 120 MB/s.

The thing is, this disables the "Enable write caching on the device" setting in Device Manager, but wherever I have read about optimizing SSD performance it is said that this setting needs to be enabled, hence the reason I am somewhat perplexed by what I am seeing.

So hopefully someone can chime in and offer their experience/opinions on this issue.

 01/30/2013 01:38 PM
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QB the Slayer
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Joined: 11/27/2012

Wow...  just a little further down is a very nice thread about just your situation.  QB Wonders why people don't look first.

 

QB



-------------------------

The MONSTER HTPC:

CPU: AMD FX-8350.||.Cooler: Corsair H80i
MB: Gigabyte 990FXA-UD7.||.RAM: 8 GB Mushkin Blackline DDR3 2000MHz (7-10-8-27-1T)
Case: CoolerMaster HAF 932.||.PSU: Corsair HX750
GPU:Asus R9 270X DirectCU II TOP.||.Audio: Creative X-Fi Titanium Fatal1ty Pro w/ Logitech Z-5300e (5.1, 280W-RMS)
System Drive: 2xSamsung 840 Pro 128GB RAID0.||.Working Drive: 2xMushkin Chronos 60GB RAID0

 01/31/2013 02:21 AM
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mongo
Peon

Posts: 4
Joined: 01/30/2013

Originally posted by: QB the Slayer Wow...  just a little further down is a very nice thread about just your situation.  QB Wonders why people don't look first.

QB

Hi!

Sorry, I saw your thread and started reading till about the middle and then stopped.

I also tried to use the search feature, but its completely broken.

I couldnt have known that you were going to discuss the issue I posted in this thread as the thread title didnt reflect this.

After your comment I went and read through your whole thread, its very informative!

So from what we have both seen, on an AMD based system using SB950 chipset and RAIDXpert, we should only use RAIDXpert to optimize the performance our RAID 0 arrays.

It would be nice to know the reasons behind this and would also be good information for other peeps with AMD systems to know, as searching Google for this issue brings no results (well I couldnt find any!).

Hopefully, both yours and this thread will get spidered so peeps will now have a reference point!

I will post this info in some of the other forums I frequent.

 01/31/2013 08:35 AM
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QB the Slayer
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Posts: 329
Joined: 11/27/2012

It probably has to do with RAID having it's own Write Cache built in, and forcing a Windows Write Cahe policy does not work with it.  Don't forget, Windows does NOT know that the disk is actually SSD's...  it just sees a RAID volume.  And as such, to configure a RAID volume optimally you use Read Ahead and Write Back, settings which can only be accessed through RAIDXpert

 

QB



-------------------------

The MONSTER HTPC:

CPU: AMD FX-8350.||.Cooler: Corsair H80i
MB: Gigabyte 990FXA-UD7.||.RAM: 8 GB Mushkin Blackline DDR3 2000MHz (7-10-8-27-1T)
Case: CoolerMaster HAF 932.||.PSU: Corsair HX750
GPU:Asus R9 270X DirectCU II TOP.||.Audio: Creative X-Fi Titanium Fatal1ty Pro w/ Logitech Z-5300e (5.1, 280W-RMS)
System Drive: 2xSamsung 840 Pro 128GB RAID0.||.Working Drive: 2xMushkin Chronos 60GB RAID0

 02/01/2013 09:22 AM
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mongo
Peon

Posts: 4
Joined: 01/30/2013

Hi!

After some more testing it seems that checking "Enable write caching on the device"has some incompatabilty with RAIDXpert.

If this is enabled when I reboot, 4K reads (AS SSD) are halved unless you go into RAIDXpert and simply set "no cache" then set back to "read ahead".

But..... 4K-64Thrd has an increase on both read and writes ??

I.e.

4K is around 130MB/s with "Enable write caching on the device" checked (and "Turn off ....." checked), RAIDXpert set to "Read ahead".

Reboot

4K is around 65MB/s, "Enable write caching on the device" stays checked but "Turn off ....." becomes unchecked.

To restore previous performance, simply do the procedure mentioned above in RAIDXpert, i.e. set no cache -> set read ahead

The Windows setting and RAIDXpert seem to not work together properly, when using "Enable write caching on the device"

For reference ive attached 2 AS SSD images

Any ideas, lol

 02/01/2013 02:39 PM
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QB the Slayer
Master Looter

Posts: 329
Joined: 11/27/2012

I am fairly certain that the Windows Write Cache Policy is a Write-Through policy...  and with a RAID volume best performance is obltained using Write-Back policy.  So when you are in RAID expert and hit submit when the check is on Write-Back you are actually changing the windows policy to write-back (which is disabling it)

 

If you want ANY read cache (Read Cache or Read Ahead) Write-Back is always selected.

 

Here is a simple test for you to illustrate what I am saying...  go to the windows policy and make sure the cache is disabled.  Then go to RAIDXpert and select no cache (this puts the write cache to write-through)...  WITHOUT rebooting go back to windows policy and you will now see it is now enabled.  This means that the Windows Write Cache Policy is actually Write-Through

 

THe windows policy and RAIDXpert actually work hand in hand

 

QB



-------------------------

The MONSTER HTPC:

CPU: AMD FX-8350.||.Cooler: Corsair H80i
MB: Gigabyte 990FXA-UD7.||.RAM: 8 GB Mushkin Blackline DDR3 2000MHz (7-10-8-27-1T)
Case: CoolerMaster HAF 932.||.PSU: Corsair HX750
GPU:Asus R9 270X DirectCU II TOP.||.Audio: Creative X-Fi Titanium Fatal1ty Pro w/ Logitech Z-5300e (5.1, 280W-RMS)
System Drive: 2xSamsung 840 Pro 128GB RAID0.||.Working Drive: 2xMushkin Chronos 60GB RAID0



Edited: 02/01/2013 at 05:16 PM by QB the Slayer
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