# How To Improve RAID 0 Performance?



## dcf-joe (Apr 9, 2010)

I am currently running two 150 gb velociraptors in RAID 0 using the on-motherboard sata II connectors. I believe that I read somewhere that using a RAID controller that plugs into the PCI-E 2.0 slots actually increases read/write performance. Is this true?

This is my current read/write performance while reading and writing a 1000 mb file 9 times, using the onboard controller:


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## wrathchild_67 (Apr 9, 2010)

You could increase your RAID stripe size to 128KB if it's not already, but I can't imagine you gaining more than 30MB/s on that benchmark. Since you're running Vista, I'm going to assume your first partition on the array is aligned. Really those are the two biggest factors affecting performance. Increasing your stripe size may lower performance if you are using the array for your OS drive. You could create two separate arrays, one with a stripe size of 16-32KB, and the other with a stripe size of 128KB. The first array would be for the OS, plus it would be short-stroked which will lower your access times for partitions on that array.


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## dcf-joe (Apr 10, 2010)

What do you mean aligned? I only have two drives in raid 0, and one partition to hold everything, in other words, I have one large 300 gb space being used from the two 150 gb's.


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## AsRock (Apr 10, 2010)

All so the Allocation size can make a big difference too. you would test it out for your needs as for example large  allocation size  is bad for the OS but i find better for a game partition.


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## wrathchild_67 (Apr 10, 2010)

AsRock said:


> All so the Allocation size can make a big difference too. you would test it out for your needs as for example large  allocation size  is bad for the OS but i find better for a game partition.



Right.

For a non-OS partition, you should set the allocation size to 64KB if the majority of the files that are accessed are over 64KB in size. Any file smaller than the allocation size automatically takes up the allocation size when measured on the disk. You will have some wasted space due to to this effect, but it will give you the best transfer rates overall when dealing with 64KB or larger files with a RAID stripe size of 64KB or higher.




dcf-joe said:


> What do you mean aligned? I only have two drives in raid 0, and one partition to hold everything, in other words, I have one large 300 gb space being used from the two 150 gb's.



If you formatted the partition during Vista setup, then it is aligned. See here: http://sqlblog.com/blogs/linchi_shea/archive/2007/02/01/performance-impact-of-disk-misalignment.aspx


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## dcf-joe (Apr 10, 2010)

Okay, that is good to know since I did use the Vista installer. I setup my raid in the bios though, after pushing I think ctrl-f7. 

I also had already set my stripe size to 128kb.


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## Carl2 (Apr 17, 2010)

I set up a Raid O array using 2 HD502HJ Samsung sata 500G 16Mb to decrease boot time, 250 Mb read, 240 mb write.  Same boot time Same performance index in Win 7 of 5.9.  Put in an Intel 160 Gb SSD to see some performance increase.
Carl2


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