- Joined
- Jul 18, 2002
- Location
- Citadel Station
I knew going in that this was going to be tricky, but I am annoyed nevertheless.
I have three Seagate ST1500DL003 drives connected to the Intel SATA2 ports of an ASRock Z68 Extreme4 board. I want to run these in RAID5.
I believe that when everything it working together I should see sequential read and write speeds of over 200MB/s from the array (as each drive is capable of over 100MB/s sustained):
http://forums.storagereview.com/index.php/topic/29166-raid-5-technical-questions/page__st__10
http://www.overclockers.com/forums/showthread.php?t=679046
http://www.overclockers.com/forums/showpost.php?p=5382038&postcount=20
I knew that this was going to take the perfect stripe size, cluster size, and partition alignment. What I didn't expect is that it may take the perfect astrological alignment as well! I have gotten very different results while using exactly the same settings for stripe, partition, and format.
I was using a fixed stripe and cluster size, and trying different align=X settings using diskpart to see what worked best. Most were giving write speeds 10-30MB/s, but I hit upon one (align=64, FWIW) that gave me 90MB/s. I wrote it down and continued trying other values, but I didn't find anything else as fast. When I repeated the settings however I got 20MB/s writes! I was determined to get the higher speed again, so I kept trying. To cut it short, I have found that perhaps one in a dozen times, using the same settings, the array will test fast, but all other times it will test slow. (I ran ATTO, CrystalDisk, and AS SDD to make sure the faster result was not an error.) Further, the "fast" ones (which I have had occur about four times now) do not seem to be exactly the same speed as each other. Worse, I had a "fast" array become slow after a reboot, so I cannot even depend on it staying the same! How can I possibly optimize the settings if the results change capriciously?
After realizing that Intel RAID5 was behaving erratically, I thought I would try RAID1, as either that or RAID1+0 was my backup plan if I could not get RAID5 working as I hoped. I built a RAID1 with Intel RST, but the results were poor. The writes were fine at 115MB/s, but the reads were slow, between 37 and 80 MB/s in ATTO. I wondered how Windows RAID would behave, so I built a mirror in Disk Management using the same cluster size. The results were much better than the Intel RST. Reads were 140MB/s in ATTO, and writes were not far behind. I tried a few different settings with Intel RST RAID1 but I never got good results.
I am frustrated with Intel RST RAID. Both level 1 and level 5 appear to be problematic, and level 5 at least, capriciously so. I am using the latest drivers, and I have tried earlier drivers as well with similar results. It was my intention to "accelerate" whatever array I built using SSD caching (Intel Smart Response Technology), and I wanted to use RAID5, otherwise I would just use Windows RAID (which allows neither).
What should I do or try now?
I have three Seagate ST1500DL003 drives connected to the Intel SATA2 ports of an ASRock Z68 Extreme4 board. I want to run these in RAID5.
I believe that when everything it working together I should see sequential read and write speeds of over 200MB/s from the array (as each drive is capable of over 100MB/s sustained):
http://forums.storagereview.com/index.php/topic/29166-raid-5-technical-questions/page__st__10
http://www.overclockers.com/forums/showthread.php?t=679046
http://www.overclockers.com/forums/showpost.php?p=5382038&postcount=20
I knew that this was going to take the perfect stripe size, cluster size, and partition alignment. What I didn't expect is that it may take the perfect astrological alignment as well! I have gotten very different results while using exactly the same settings for stripe, partition, and format.
I was using a fixed stripe and cluster size, and trying different align=X settings using diskpart to see what worked best. Most were giving write speeds 10-30MB/s, but I hit upon one (align=64, FWIW) that gave me 90MB/s. I wrote it down and continued trying other values, but I didn't find anything else as fast. When I repeated the settings however I got 20MB/s writes! I was determined to get the higher speed again, so I kept trying. To cut it short, I have found that perhaps one in a dozen times, using the same settings, the array will test fast, but all other times it will test slow. (I ran ATTO, CrystalDisk, and AS SDD to make sure the faster result was not an error.) Further, the "fast" ones (which I have had occur about four times now) do not seem to be exactly the same speed as each other. Worse, I had a "fast" array become slow after a reboot, so I cannot even depend on it staying the same! How can I possibly optimize the settings if the results change capriciously?
After realizing that Intel RAID5 was behaving erratically, I thought I would try RAID1, as either that or RAID1+0 was my backup plan if I could not get RAID5 working as I hoped. I built a RAID1 with Intel RST, but the results were poor. The writes were fine at 115MB/s, but the reads were slow, between 37 and 80 MB/s in ATTO. I wondered how Windows RAID would behave, so I built a mirror in Disk Management using the same cluster size. The results were much better than the Intel RST. Reads were 140MB/s in ATTO, and writes were not far behind. I tried a few different settings with Intel RST RAID1 but I never got good results.
I am frustrated with Intel RST RAID. Both level 1 and level 5 appear to be problematic, and level 5 at least, capriciously so. I am using the latest drivers, and I have tried earlier drivers as well with similar results. It was my intention to "accelerate" whatever array I built using SSD caching (Intel Smart Response Technology), and I wanted to use RAID5, otherwise I would just use Windows RAID (which allows neither).
What should I do or try now?
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