9 Replies Latest reply on Nov 1, 2018 11:28 AM by adgate

    High availability with shared datastore

    brothersofield Lurker

      Hello guys,

       

      I have to set up 2 machine with Vmware 6 and at the same time providing high availability fot the VMs created over there, but in this my project we do not gonna use External storage, because it will use just to couple vms, and then I was searching of how to use local shared datastore, nonetheless I've read some thing regarding of VSan, but I can't understand it very well and if i would be able to set up this machine in order to share their datastore.

      I've found some post, but it wasn't clear.

       

      Can someone help me with that pls?

       

       

        • 1. Re: High availability with shared datastore
          TheBobkin Virtuoso
          vExpertVMware Employees

          Hello brothersofield,

           

           

          Welcome to Communities.

           

          "and then I was searching of how to use local shared datastore"

          There is no feasible way in ESXi to share locally-attached drives for the purpose of availability - even if this was possible, how can you access the storage on a host when it has lost power/network or otherwise crashed?

           

          "nonetheless I've read some thing regarding of VSan, but I can't understand it very well and if i would be able to set up this machine in order to share their datastore."

          vSAN provides availability to the data by storing multiple replicas of the data on multiple hosts (+ Witness data to confirm which copy of the data is most current in the event of loss of a replica); e.g. in a 3-node cluster, Host1 has the 1st copy of the vmdk data, Host2 has the 2nd copy of the vmdk data and Host3 has the Witness-component - we can lose any one host here and still have a) a full copy of the data available and b) Quorum (e.g. >50% of all components available).

          Unfortunately it is not just a case of enabling vSAN on the hosts - this requires its own licensing (on top of ESXi licensing), hardware components that are certified and supported for running vSAN (controller(s), cache-tier SSD(s) and capacity-tier HDD(s)/SSD(s)) and if you were going to operate with just 2 data-nodes then you would require some other infrastructure (or Cloud) to host the Witness Appliance on.

          I would advise talking to your partner/hardware vendor for pricing of a 2-node (+ Witness) set-up (either ReadyNodes or Build-Your-Own) and maybe consider the pricing of this vs a small NAS (if high performance isn't a requirement).

           

           

          Bob

          • 2. Re: High availability with shared datastore
            vijayrana968 Master
            vExpert

            Local storage can be only shared as a vSAN. And there are some pre-requisites to configure vSAN, very basics are..

             

            1. Local storage should have SSD drives installed.

            2. vSphere Enterprise Plus license.

             

            Many more there VMware Knowledge Base

            • 3. Re: High availability with shared datastore
              TheBobkin Virtuoso
              VMware EmployeesvExpert

              Hello vijayrana968

               

               

              "Local storage can be only shared as a vSAN. And there are some pre-requisites to configure vSAN, very basics are..

              1. Local storage should have SSD drives installed.

              2. vSphere Enterprise Plus license."

               

              You should consider reading the kb article you linked - it doesn't say you need vSphere Enterprise Plus to run vSAN because this is false - vSAN licensing is independent of vSphere licensing and one can run vSAN on vSphere Essentials if they want to.

              https://www.vmware.com/content/dam/digitalmarketing/vmware/en/pdf/products/vsan/vmware-vsan-66-licensing-guide.pdf

               

              Also there is no "should" as to having SSDs - you MUST have SSDs (or NVMe) as cache-tier devices.

               

               

              Bob

              1 person found this helpful
              • 4. Re: High availability with shared datastore
                brothersofield Lurker

                Hi Guys, tks for answering me.

                 

                So, in other words, it means that if I wanted H.A between my physicals machines I would have to have 3 local server or more, and then I would be able to use vsan and then share the local datastore in order to remain high  availability.

                So, What would you suggest to this project, once H.A is mandatory?

                 

                Tks

                • 5. Re: High availability with shared datastore
                  vijayrana968 Master
                  vExpert

                  I am very clear on SSD's part, however checking licensing requirements. Thanks for info

                  • 6. Re: High availability with shared datastore
                    TheBobkin Virtuoso
                    vExpertVMware Employees

                    Hello brothersofield,

                     

                     

                    "So, in other words, it means that if I wanted H.A between my physicals machines I would have to have 3 local server or more, and then I would be able to use vsan and then share the local datastore in order to remain high  availability."

                    If HA (e.g. the ability to restart VMs following the host they were running on becomes unavailable) is a requirement then you must have some form of shared storage, be it VMware vSAN (or similar alternatives) or hosts connected to a SAN/NAS.

                     

                    For vSAN you wouldn't necessarily have to have 3 full servers as I said previously; you can run a 2-node Direct-Connect (no switch in-between required) + Witness on some other infrastructure/Cloud (requires <200ms RTT latency and pretty low bandwidth ~2MBps per 1000 components) or 1+1+1 Stretched-Cluster (data-node in 1st site, data-node in 2nd site, Witness in 3rd site).

                     

                    "So, What would you suggest to this project, once H.A is mandatory?"

                    I would advise talking to the stakeholders/business/customer regarding priorities and budget, and then based on this engage your partner(s)/hardware vendor(s) regarding pricing for said solution and then comparing this to other potential options, if not going with ReadyNodes then do please ensure the BOM for controllers+SSDs+HDDs/SSDs are all on the vSAN HCL or potentially we will be having a non-pleasant support call in the future   .

                    If this is an environment that has the potential to grow or change over time then vSAN is a good choice as it is just a case of adding more nodes and/or storage for expansion.

                     

                    vijayrana968  - Apologies if I came across as barky or abrupt before, but I operate in a space where incorrect or misinformation can be very dangerous (especially in unskilled hands); rule of thumb on Communities (or anywhere) should be that if you are not 99% (or greater) sure about something then better to not say anything than to say something incorrect - you can't know what impact this may have in the future e.g. someone setting up a solution with bad info and having serious negative outcomes when it goes wrong (e.g. loss of job, customers, sanity).

                    Tis only fake internet-points/pixels to be gained so in my opinion it is not worth it (unless you are sure ).

                     

                     

                    Bob

                    • 7. Re: High availability with shared datastore
                      vijayrana968 Master
                      vExpert

                      I respond in general as question was for basic understanding.... so I wrote it 'should'  (I know this is 'Must') and for rest of the things I referred KB.

                       

                      on vSAN part, we haven't that single setup since we have all FC SAN so I was digging up vSAN HOL by vmware and learnt basics, skipping licensing details. Post your comment I recall vSAN is available as separate product functional with vSphere. Your point is agreed and noted

                      • 8. Re: High availability with shared datastore
                        patrickds Expert

                        Instead of vSan, you could look at other products that provide replicated shared storage, running in VMs, so you could use internal storage for HA.

                        For example (many more exist, some open source):

                        https://www.starwindsoftware.com/

                        https://www.datacore.com/products/hyper-converged-infrastructure/