I have done some more testing. Here are ATTO Disk benchmark:
1) RAID 5 with 5x HDD
2) RAID 5 with 4x HDD
3) RAID 5 with 3x HDD
4) stripe RAID 0 with 5x HDD - just for testing, if there is not some problem with five drives setup
I have done testing with 3, 4 and 5 drives in RAID 5 configuration with write back caching. As you can see, there is really some problem with more than four drives. But with basic stripping is everything ok.
It looks like there is some problem with parity calculations or caching.
Thank you very much and have a nice day
You may want to wait until the initialization is completed as the process may affect performance.
Thank you for the answer.
But I the raid volume with five drives was completely initialized. It took about 16 hours. The benchmark was done after the initialization was finished. So there is no problem.
I have tried two ways to configure RAID 5 with five HDDs:
1) Clean setup - I have configured all five drives during configuration wizard, I have selected all space with 128kB stripe size. I was waiting about 16 hours to finish the initialization and after that was made the first benchmark in my first post (I have also tried NTFS format with different allocation unit size 4kB,16kB, 64kB). The result was about 25MB/s.
2) HDD add - I have configured RAID 5 with four HDDs. I have made second benchmark with 240MB/s write speed, after the initialization was completed. I have added the fifth drive to the volume and gave it time to finish the rebuild. The write speed was the same like after the clean setup with five drives. Only 25MB/s.
On this picture you can see my raid setup with four drives, and with "Add disk" action I have added fifth drive.
I have seen the tomshardware forum, but it is write back cache configuration and even only with three drives. It is not my situation.
I found another person with similar problem on Z87 chipset.
Thank you very much and have nice day
I have done some more testing with the raid setup. Finally I found the solution with write performance. I have changed stripe size from 128kB to 32kB and write speeds are ok. joe_intel this is solution.
I am on a write speed about 300MB/s and it is great
Here you can see my RST volume setup and ATTO benchmark result:
I would consider this behavior as a RST bug. But I am happy now.
I hope, that this information will help somebody else in the future.
Have a nice day
Does anyone here at Intel have any remarks regarding this bug? I have struck this problem with 6 drives and had no issue with 5.
We have a small run of prototype appliances here and are running into this issue on all of them!
This is a major issue as we may have to abandon the use of INTEL RST tech altogether.need that 128k Stripe on "X" number of drives like usual.