12 Replies Latest reply on Jun 26, 2019 1:15 AM by khairulnixam

    Very slow speed on SSD

    rajibimran Lurker

      Hi experts,

      I am getting strange behavior for ESXI6.5 (installed as test at my home clone server). Like i have installed 2 SSD, one is Intel M.2 and another is transcend SATA III SSD. from both SSD i have created datastore. But i am getting different speed on the 2 SSD like on intel i am getting full speed but on transcend i am getting only 16mbps speed. tried to search google, but didnt got any solution. my ESXI is installed on intel M.2 SSD.



      Pls find the speed diff (2.02 vs 22.77 MB/s) t10.ATA is transcend and NVMe is Intel M.2


      Pls suggest what to do.


      My server config:

      Processor: Intel(R) Core(TM) i7-6800K

      RAM: 128GB

      Motherboard : GA-X99-Ultra Gaming

      No RAID


        • 1. Re: Very slow speed on SSD
          peetz Master
          vExpertUser Moderators

          Hi Rajib,


          welcome to the forums!


          ESXi 6.5 includes a new native driver (vmw_ahci) for SATA AHCI controllers, but that introduces performance problems with a lot of controllers and/or disks.

          Try to disable the native driver and revert to the older sata-ahci driver by running


          esxcli system module set --enabled=false --module=vmw_ahci

          in an ESXi shell. Reboot the host to make the change effective.

          - Andreas

          4 people found this helpful
          • 2. Re: Very slow speed on SSD
            JonReevesUSA Lurker

            This fixed it for me.


            Was experiencing Latency of > 1000ms and Write Speed of 1Mbps on my M.2 SSD (Transcend 2260). Motherboard is a H110T/CSM.


            Thanks for the advice.

            • 3. Re: Very slow speed on SSD
              roblangston Lurker

              I was also having this issue, after 3 days trying to troubleshoot found this solution on a blog post.


              One issue I still have is that my 4 port Syba PCIe controller card now vanishes after disabling vmw_ahci and I am restricted to using the SATA ports on the motherboard.  Is there also a workaround for this?

              • 4. Re: Very slow speed on SSD
                rajibimran Lurker

                Thanks Andreas,

                Your suggestion worked for me, now i am getting avg speed 250Mbps from SATA III SSD .


                Hope will get the full I/Ops from SSD.



                Rajib Imran

                • 5. Re: Very slow speed on SSD
                  BrianCunnie Novice

                  Thanks peetz, you saved me: I spent hours trying to determine why my 1TB Crucial MX300 M.2 2280 SSD had such abysmal performance (updating BIOS on my skull canyon, updating ESXi, etc...), and now, thanks to your post, I'm getting ~500MB/s read write.

                  • 6. Re: Very slow speed on SSD
                    MauriceD Lurker

                    Does this or something like it apply to ESXi 5.5 ?


                    I have an IBM X3550M5 and boot ESXi off an internal SD card.

                    The ESXi was installed from the latest download of 5.5 (U3?)

                    There is a single SSD drive for VMware View desktops -

                    But actions like clone to replica take well more than the 90-minute limit for a simple Win7 VM.

                    Even creating the clone files (not replica) for View desktops was impossible.

                    Trying to migrate a 36GB Win2012R2 Terminal server to the SSD is about 50% done after 3 hours.

                    The SSD is unusable...



                    • 7. Re: Very slow speed on SSD
                      getarhythm Lurker

                      What is the permanent fix for this issue, should we expect a corrected native driver from VMware, or will this require a firmware upgrade on the part of the drive vendors?

                      • 8. Re: Very slow speed on SSD
                        amd2002a Novice

                        I can confirm that this works for me to increase SSD access speed on my Intel NUC (BOXNUC7I7BNH).

                        • 9. Re: Very slow speed on SSD
                          gecman47 Novice

                          This was my problem as well.


                          WARNING: Doing this at least for me erases all the VMs on the aforementioned drive. Migrate as needed.

                          • 10. Re: Very slow speed on SSD
                            mackuzz Lurker

                            Please tell the noob, does this problem affect ESXi 6.7? And how can I check, does it affect my system?
                            And what will happen with my ESXi, installed on one of the SSD's?

                            • 11. Re: Very slow speed on SSD
                              pasqua Lurker

                              tried the command on a 6.7.

                              Deploying an OVA and I am getting 22.82....


                              I have a Samsung 860 EVO mSATA 1Tb SSD.


                              i re-enabled it, I got max 11.81.


                              Kind of crappy either way. Not SSD speeds IMO.

                              • 12. Re: Very slow speed on SSD
                                khairulnixam Lurker



                                Running 6.7u2XXX

                                this does not help to solve my problem... esxcli system module set --enabled=false --module=vmw_ahci


                                EDIT. However, the native driver did increate the performance around 17% of read and write speed.


                                Doing further testing and look like Hyper-V is ways faster then esxi.. tested using same box and same storage....



                                So believe this is esxi driver limitation.