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    RAID Performance Calculators

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    • DustinB3403D
      DustinB3403
      last edited by

      Just doing some searching around to calculate the performance of a specific build I'm proposing and would like some clarity on RAID Performance Calculators. Specifically this one. http://wintelguy.com/raidperf.pl

      In my proposal I'm using Samsung EVO 850 1TB drives.

      RAID Type: RAID 5 (stripe with parity)

      Number of drives in a RAID group: 12

      Number of RAID groups: 1

      Single disk performance: IO/s MB/s
      Read performance: 540
      Write performance: 520

      Read operations (%): (using the stock 50%)

      But where would I find existing "Read operations percentage" ? This seems odd to calculate. I'm sure it has a logical reason for being there.

      Does this mean: "What percentage of your access is people only reading something and then closing it?" And if so, how would I calculate this?

      scottalanmillerS Reid CooperR 3 Replies Last reply Reply Quote 3
      • DashrenderD
        Dashrender
        last edited by

        That Dell tool (was it called DMAC?) can do this. You have to run a utility on your system that watches for these types of things. It's not perfect, but you're only looking for a rough guess.

        scottalanmillerS J 2 Replies Last reply Reply Quote 0
        • DustinB3403D
          DustinB3403
          last edited by

          Can anyone think of a good tool that could be used free of charge?

          Searching around there are a ton of paid solutions, but this seems rather excessive for the limited use we'd actually use it.

          1 Reply Last reply Reply Quote 0
          • scottalanmillerS
            scottalanmiller
            last edited by

            MB/s is not something you generally care about at all. It's IOPS that matter.

            1 Reply Last reply Reply Quote 0
            • scottalanmillerS
              scottalanmiller @DustinB3403
              last edited by

              @DustinB3403 said:

              But where would I find existing "Read operations percentage" ? This seems odd to calculate. I'm sure it has a logical reason for being there.

              Because it changes significantly what the IOPS are based on the RAID level. You get generally quite different read and write performance, so knowing you read and write blend is necessary to know how many IOPS you will get from your setup.

              1 Reply Last reply Reply Quote 0
              • scottalanmillerS
                scottalanmiller @Dashrender
                last edited by

                @Dashrender said:

                That Dell tool (was it called DMAC?) can do this. You have to run a utility on your system that watches for these types of things. It's not perfect, but you're only looking for a rough guess.

                DPACK

                1 Reply Last reply Reply Quote 0
                • J
                  Jason Banned @Dashrender
                  last edited by

                  @Dashrender said:

                  That Dell tool (was it called DMAC?) can do this. You have to run a utility on your system that watches for these types of things. It's not perfect, but you're only looking for a rough guess.

                  DPACK and it's not a calculator it runs on the system to calculate used IOPS.

                  DashrenderD 1 Reply Last reply Reply Quote 0
                  • scottalanmillerS
                    scottalanmiller @DustinB3403
                    last edited by

                    @DustinB3403 said:

                    Does this mean: "What percentage of your access is people only reading something and then closing it?" And if so, how would I calculate this?

                    Sort of. It is "What percentage of IOPS are reading from storage versus writing to it."

                    1 Reply Last reply Reply Quote 1
                    • DashrenderD
                      Dashrender @Jason
                      last edited by

                      @Jason said:

                      @Dashrender said:

                      That Dell tool (was it called DMAC?) can do this. You have to run a utility on your system that watches for these types of things. It's not perfect, but you're only looking for a rough guess.

                      DPACK and it's not a calculator it runs on the system to calculate used IOPS.

                      yep and it should be telling you how many for write vs how many for read... there's your percent.

                      1 Reply Last reply Reply Quote 0
                      • StrongBadS
                        StrongBad
                        last edited by

                        You could use tools inside of the operating systems to determine the W/R mix on a per OS basis. Or similar, I suspect, in most hypervisors.

                        1 Reply Last reply Reply Quote 0
                        • Reid CooperR
                          Reid Cooper @DustinB3403
                          last edited by

                          @DustinB3403 said:

                          Single disk performance: IO/s MB/s
                          Read performance: 540
                          Write performance: 520

                          Those numbers are very small for IOPS from SSDs. I would expect at least one hundred times those numbers. Maybe more.

                          donaldlandruD 1 Reply Last reply Reply Quote 0
                          • donaldlandruD
                            donaldlandru @Reid Cooper
                            last edited by donaldlandru

                            @Reid-Cooper said:

                            @DustinB3403 said:

                            Single disk performance: IO/s MB/s
                            Read performance: 540
                            Write performance: 520

                            Those numbers are very small for IOPS from SSDs. I would expect at least one hundred times those numbers. Maybe more.

                            Those numbers are the max r/w speed is MB/s not iops numbers, as @scottalanmiller pointed out above really don't matter in this question...

                            1 Reply Last reply Reply Quote 0
                            • DustinB3403D
                              DustinB3403
                              last edited by

                              So here's a link to the exact drive I'm looking at.

                              To save a few clicks

                              Performance
                              Max Sequential Read Up to 540 MBps

                              Max Sequential Write Up to 520 MBps

                              4KB Random Read
                              Random read (QD1) [IOPS]: up to 10,000 IOPS
                              Random read (QD32) [IOPS]: up to 98,000 IOPS

                              4KB Random Write
                              Random Write (QD1) [IOPS]: up to 40,000 IOPS
                              Random Write (QD32) [IOPS]: up to 90,000 IOPS

                              1 Reply Last reply Reply Quote 0
                              • DashrenderD
                                Dashrender
                                last edited by

                                IOPs with SSD are so large in comparison to their HDD brethren, just one drive often beats an entire array of SAS 15K RAID 10 drives (8 drives @190 IOPs/drive = 1520 random read / 760 random write).

                                These are just simple ballparks.

                                1 Reply Last reply Reply Quote 0
                                • DustinB3403D
                                  DustinB3403
                                  last edited by

                                  Yeah I did the math on the SSD drives above, and the rates IOPS is 4.4 GB/m.

                                  Which there's no way SR (spinning rust) could keep up.

                                  scottalanmillerS 1 Reply Last reply Reply Quote 0
                                  • coliverC
                                    coliver
                                    last edited by

                                    Can a SSD drive saturate the SATA connection they are attached to? Or are they not that fast yet.

                                    I know most enterprises will probably start moving to PCIe SSD drives or at least a controller to integrate them.

                                    1 Reply Last reply Reply Quote 1
                                    • DustinB3403D
                                      DustinB3403
                                      last edited by

                                      Well SATA supports up to 6GB/S

                                      With my calculations I can push 4.4GB/m or 700MB/S (write)

                                      So I don't think so.

                                      coliverC DashrenderD 2 Replies Last reply Reply Quote 0
                                      • coliverC
                                        coliver @DustinB3403
                                        last edited by

                                        @DustinB3403 said:

                                        Well SATA supports up to 6GB/S

                                        With my calculations I can push 4.4GB/m or 700MB/S (write)

                                        So I don't think so.

                                        Thanks.

                                        1 Reply Last reply Reply Quote 0
                                        • DashrenderD
                                          Dashrender @DustinB3403
                                          last edited by

                                          @DustinB3403 said:

                                          Well SATA supports up to 6GB/S

                                          With my calculations I can push 4.4GB/m or 700MB/S (write)

                                          So I don't think so.

                                          Not a single drive. But an array definitely can.

                                          DustinB3403D 1 Reply Last reply Reply Quote 0
                                          • DustinB3403D
                                            DustinB3403 @Dashrender
                                            last edited by

                                            @Dashrender my calculations are a 12 disk RAID 5 array.

                                            A bigger system might.

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