Rapid Storage Technology
Intel® RST, RAID
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[Z68] Another thread about RAID5 performances


Hello world,

I'm building a personal server based on a Z68 motherboard (Asrock Extreme3 Gen3) via a PCIe add-on card, so my Intel storage controller is totally free. I own 6* 1,5 TB HDD (4* Seagate 7200.11 + 2* WD Caviar Green WD15EARS) and I would like to make a RAID-5 array via Intel RST. I basically made a 6 HDD array, resultats : useless write performance (around 30 MB/s). Made the same with 5 HDD, the same. Then with 4 HDD, it's way better (120+ MB/s). For those 3 tests I was in 128 kbps stripe size (the RAID is to store large files, movies, etc.). Then I've read a lot of thread, here on Intel Support Community and also on Storage Review forums. I read that I must align my partition, that I must change my strip size, cluster size, etc... I'm lost ! Here are a few questions, if you can help me :

1/ why, in RST software, is it needed to initialize the volume only with 5 or 6 HDDs and not with 4 or less?

2/ how to chose the best stripe size, I thought it was about the file you were using... but I've read it depends on HDDs

3/ will having two different types of HDDs be a problem? (about performances)

4/ while initialising, can I do something with the volume?

5/ Is it better to stay with 5 HDDs than 6? (still about performances)

6/ when I'll have my futur RAID5 volume created (reading your advices), what next shall I do?

Best regards and thanks for any help,


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Hi again,

Without really understunding why, without any alignement, I tried 5 HDDs with 32 kb strip size and 64kb cluster NTFS size. Result : 30 > 135 MB/s !

I'm happy, but if you can explain me a little more why it change like this, it would be nice.



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