Slow writes with disabled write caching on the disk

Nikooo · 11-18-09, 10:08 PM

Hi guys, maybe someone has an answer for my question ...

I have 2 HDDs - WD Caviar Black 640Gb,
one is the OS drive and the other is empty and formatted.
When I copy a movie file to the empty disk I get write speed of around 100Mb/ sec and this is with "Enable write caching on the disk" enabled,
when I disable it I get write speed around 6-7 Mb/s.
I am using Total Commander so when I copy I can see the speed.

I've tried this on windows installed with the HDD in regular Sata and also in AHCI mode.
The same is confirmed when I am doing a write benchmark with HDTune Pro on the empty disk

Is this normal behaviour ?
I had an idea that this cache is helping the writes but not to such great extent. Also I think I am supposed to get higher write speeds of big files even when not having this cache enable.
I've also tried the file benchmark in HDTune and get similar big discrepancies in the write speeds with the cache enabled/disabled.

Any ideas ?

in the 1st and 3rd image the cache is enabled

visbits · 11-18-09, 10:29 PM

write caching caches the data being written in ram till the IO controller can get to it, that's what accelerates the performance. I figured the name "WRITE caching" would kinda hint that

Nikooo · 11-19-09, 09:05 AM

YUP, that's my understanding too, just wondering ...
when I copy big files with it disabled I ONLY get 6-7 Mb/s,that doesn't look quite normal. These hard disks nowadays are quite fast and I thought I should get more than that ...
just wondering if these are really normal numbers or I have software/hardware issue.

EarthDog · 11-19-09, 09:08 AM

The issue is you are disabling WRITE caching. Enable it, no problems.

JCLW · 11-19-09, 09:42 AM

What controller are you using?

Do you mind running ATTO and posting a screenshot? http://www.techpowerup.com/downloads...ark_v2.34.html

Nikooo · 11-19-09, 11:12 AM

It's on ICH10R and I am using Windows XP sp3
I wasn't sure about the Direct I/O, so I made with and without it.

Actually when I am copying big files with Windows Explorer or Total Commander the write speeds I am getting are those in the 3rd picture

Nikooo · 11-20-09, 04:28 AM

So, no ideas...
come on guys ...

EarthDog · 11-20-09, 06:37 AM

Whats the issue? If you have write caching enabled, like you should, the disk performs fine right?

JCLW · 11-20-09, 06:43 AM

I thought at first you were disabling the volume write back cache in the intel Matrix Storage Manager.

Now I understand you are disabling the Windows write back cache.

That is normal behaviour when disabling the Windows write back cache.

You should leave your drives in AHCI mode if possible, as this is a newer and more advanced mode that offers more features.

Nikooo · 11-20-09, 10:38 AM

All clear now. Thanks a bunch !!! Enabled+AHCI it is !!!

deathman20 · 11-20-09, 12:06 PM

Enabled... Period

Problem solved. Be happy with more performance hehe.

11-18-09, 10:08 PM	Thread Starter #1
Nikooo New Member Join Date: Jan 2009 Location: Montreal	Slow writes with disabled write caching on the disk Hi guys, maybe someone has an answer for my question ... I have 2 HDDs - WD Caviar Black 640Gb, one is the OS drive and the other is empty and formatted. When I copy a movie file to the empty disk I get write speed of around 100Mb/ sec and this is with "Enable write caching on the disk" enabled, when I disable it I get write speed around 6-7 Mb/s. I am using Total Commander so when I copy I can see the speed. I've tried this on windows installed with the HDD in regular Sata and also in AHCI mode. The same is confirmed when I am doing a write benchmark with HDTune Pro on the empty disk Is this normal behaviour ? I had an idea that this cache is helping the writes but not to such great extent. Also I think I am supposed to get higher write speeds of big files even when not having this cache enable. I've also tried the file benchmark in HDTune and get similar big discrepancies in the write speeds with the cache enabled/disabled. Any ideas ? in the 1st and 3rd image the cache is enabled Attached Images
	QUOTE Thanks

11-18-09, 10:29 PM	#2
visbits Member Join Date: Jan 2009	write caching caches the data being written in ram till the IO controller can get to it, that's what accelerates the performance. I figured the name "WRITE caching" would kinda hint that __________________ Using Ubuntu does not make you good with linux. HEATWARE
	QUOTE Thanks

11-19-09, 09:05 AM	Thread Starter #3
Nikooo New Member Join Date: Jan 2009 Location: Montreal	YUP, that's my understanding too, just wondering ... when I copy big files with it disabled I ONLY get 6-7 Mb/s,that doesn't look quite normal. These hard disks nowadays are quite fast and I thought I should get more than that ... just wondering if these are really normal numbers or I have software/hardware issue.
	QUOTE Thanks

11-19-09, 09:08 AM	#4
EarthDog Senior PITA Member Overclockers.com Editor Join Date: Dec 2008 Location: Stuck in Maryland...	The issue is you are disabling WRITE caching. Enable it, no problems. __________________ Should I R0 my SSD? / SandyBridge / Ivybridge Overclocking Guide / AMD Overclocking Guide / Power Supply Guide SSD Reliability/Write Endurance / JOIN THE BENCHING TEAM! / Bulldozer Overclocking Guide / Forum Etiquette Want to see your writing featured on the overclockers.com Front Page? PM me, I can help! "We have more information and more ways of accessing it than ever, yet seem increasingly less inclined to do so."- Michael Wilbon
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11-19-09, 09:42 AM	#5
JCLW Member Join Date: Apr 2002 Location: Back in Toronto	What controller are you using? Do you mind running ATTO and posting a screenshot? http://www.techpowerup.com/downloads...ark_v2.34.html __________________ ♫♪ ☺ ♫♪
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Slow writes with disabled write caching on the disk

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11-19-09, 11:12 AM	Thread Starter #6
Nikooo New Member Join Date: Jan 2009 Location: Montreal	It's on ICH10R and I am using Windows XP sp3 I wasn't sure about the Direct I/O, so I made with and without it. Actually when I am copying big files with Windows Explorer or Total Commander the write speeds I am getting are those in the 3rd picture Attached Images
	QUOTE Thanks

11-20-09, 04:28 AM	Thread Starter #7
Nikooo New Member Join Date: Jan 2009 Location: Montreal	So, no ideas... come on guys ...
	QUOTE Thanks

11-20-09, 06:37 AM	#8
EarthDog Senior PITA Member Overclockers.com Editor Join Date: Dec 2008 Location: Stuck in Maryland...	Whats the issue? If you have write caching enabled, like you should, the disk performs fine right? __________________ Should I R0 my SSD? / SandyBridge / Ivybridge Overclocking Guide / AMD Overclocking Guide / Power Supply Guide SSD Reliability/Write Endurance / JOIN THE BENCHING TEAM! / Bulldozer Overclocking Guide / Forum Etiquette Want to see your writing featured on the overclockers.com Front Page? PM me, I can help! "We have more information and more ways of accessing it than ever, yet seem increasingly less inclined to do so."- Michael Wilbon
	QUOTE Thanks

11-20-09, 06:43 AM	#9
JCLW Member Join Date: Apr 2002 Location: Back in Toronto	I thought at first you were disabling the volume write back cache in the intel Matrix Storage Manager. Now I understand you are disabling the Windows write back cache. That is normal behaviour when disabling the Windows write back cache. You should leave your drives in AHCI mode if possible, as this is a newer and more advanced mode that offers more features. __________________ ♫♪ ☺ ♫♪
	QUOTE Thanks

11-20-09, 10:38 AM	Thread Starter #10
Nikooo New Member Join Date: Jan 2009 Location: Montreal	All clear now. Thanks a bunch !!! Enabled+AHCI it is !!!
	QUOTE Thanks

11-20-09, 12:06 PM	#11
deathman20 High Speed Senior Join Date: Aug 2002 Location: Where the Cheese Heads Live	Enabled... Period Problem solved. Be happy with more performance hehe. __________________ -=The Gamer=- MSI Z68A-GD65 (G3) \| i5 2500k @ 4.5Ghz \| 1.3875V \| 28C Idle / 65C Load (LinX) 8Gig G.Skill Ripjaw PC3-12800 9-9-9-24 @ 1600Mhz w/ 1.5V \| TR Ultra eXtreme 120 w/ 2 Fans Sapphire 7950 VaporX 1150/1500 w/ 1.2V/1.5V \| 32C Idle / 64C Load \| 2x 128Gig Crucial M4 SSD's BitFenix Shinobi Window Case \| SilverStone DA750 \| Dell 2405FPW 24" Screen -=The Server=- Synology DS1511+ \| Dual Core 1.8Ghz CPU \| 30C Idle / 38C Load 3 Gig PC2-6400 \| 3x Samsung F4 2TB Raid5 \| 2x Samsung F4 2TB Heat
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