5 Replies Latest reply on Aug 1, 2014 10:53 AM by kevin_intel

    Slow write speed on intel Raid 5 (6xRED 4tb)

    Tassadar

      Hi all,

       

      I hope someone can lend me a hand since now I have get out of ideas.

       

      I've built a raid 5 on a Asrock z87 extreme6 using six Western Digital RED 4tb that are connected to the six intel controller SATA3 ports, with the aim of creating a 20Tb Raid 5. The OS is Windows 8.1 x64.

       

      I created the raid from the BIOS utility selecting 64kb size (I had option of selecting 64 and 128 but the utility reccomended 64kb in case of raid 5). Once in Windows I formatted the raid unit with a 20Gb partition and write speed was really slow (10 MB/s max), even after waiting raid to be completely constructed (it took several hours)

       

      After reading and looking for information I enabled write cache and disabled write-cache buffer flushing. I also set simultaneous on in the Intel Rapid Storage Technology panel. After doing this the write speed increased to 25-30 MB/s.

       

      I have notice that physical cluster size is 4098 bytes (usual on those 4tb disks), but logical cluster size is 512 bytes:

       

      [IMG]http://i61.tinypic.com/2qkmsfa.png[/IMG]

       

      Shouldn't those cluster sizes match to have a good performance? In this case, how to change it?

       

      I've try to delete partition and create again, but selecting different cluster sizes for que partition, and the best performance is using 64kb (the stripes size), but it's only 50-60 MB/s actual speed copying a big MKV file from an SSD, and even doing it if doesn't makes any change on the capture where we see the 512 bytes for logical sector size.

       

      AS SSD Benchmark seems to tell that partition is correctly aligned:

       

      [IMG]http://i61.tinypic.com/23jlthz.png[/IMG]

       

      The results of the speed here seems ok, but as I told, real speed never exceeds 58-59 mb/s in writes.

       

      I attack a capture of fdisk, I really don't know if it's ok or bad aligned:

       

      [IMG]http://i61.tinypic.com/2z83leh.png[/IMG]

       

      ATTO DISK Benchmark:

       

      [IMG]http://i57.tinypic.com/13zread.png[/IMG]

       

      Those 6 discs were installed on a NAS, having a write speed higher than 80 mb/s, where is the problem here?

       

      Many thanks in advance