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  • 1.  vSAN in 2Host Cluster??

    Posted Apr 11, 2017 01:37 PM

    Hi,

    First of all im rather new to vmware, currently running a ESX 5.5 server with local storage with 4 non critical guests with great success

    Its time for us to update sevral of our servers so we are talking about going for vmware and virtulize them instead. Questions were raised about how we should do it best way, and as allways we have a budget that is quite tight. We do allow some downtime, only requirement is that we can get back online as soon as human possible, today we have identical servers that we need to startup.

    To start with we are going to host between 8-12vms (will probaly grow in the future). For this we were thinking to get 2x Dell poweredge 730, 256gb ram, 1x400gb SSD 2x1.2TB Spinning. 1CPU 16C/32T (best license wise?, Windows 2016 Datacenter=Cores and vmware=CPU Socket), NIC Ports 4x 1GBE 2x 10GBE

    Our Initial plan was to use them as two invidual hosts (aka no cluster or shared storage) issue is going to be to keep the vms updated on the "offline" host. Ive started to lean against vSAN with a 2host cluster, hybrid disk solution, and use vmware witness appliance.

    Seeking advice on whats the best possible solution?

    When using 2host cluster if i set FTT=1 one can go down And without impact right?

    HDDs: Do i do RAID1 (or RAID10, requires more disk ofc) on each host before adding them to vSAN storage or do i just run them as individual hdds?

    If going for hardware spec above i will require 2x vSAN standard license and for Essentials (no VM-HA and so on) or Essentials Plus?

    vmnetwork and vSAN will be using the 10GBE NIC ports

    Br

    Simon



  • 2.  RE: vSAN in 2Host Cluster??

    Posted Apr 11, 2017 11:54 PM

    Hello Simon,

    Firstly, welcome to Communities and using VMware products, pop in when you can!

    Configuration:

    As per your question regarding licenses, as one is based on cores and the other sockets you will have to do the math on that based on the requirements and cost of each with comparison of the possible configurations.

    Maybe check out the prices of 3x800GB HDD vs 2x1.2TB HDD configuration as this will likely have better performance and less issues with multiple components of larger vmdk objects being forced to use the same disks.

    Also, try to avoid SATA HDDs, they cannot keep up compared to SAS HDD drives.

    Downtime:

    Assuming you have a VMFS datastore on the existing standalone ESXi host, you should be able to Enhanced vMotion (storage and compute) from that local datastore to vsandatastore and the vSAN hosts(assuming Essentials Plus or higher licensing AFAIK) once they are managed by the same vCenter.

    Alternatively, if you have some shared storage (SAN or NAS) you could migrate the VMs and/or back-up/restore/convert the physical boxes to here as a staging for migrating to vSAN (probably not necessary but depends on the situation).

    vSAN implementation:

    If 2 nodes with the specified compute resources will comfortably run the workload (low-ball this as in a node/disk-group failure scenario all will be running on the remaining host until the other is recovered/remediated) then a 2-node Direct-connect set-up would work.

    Note that the Witness Appliance needs another ESXi cluster to run in, or alternatively I have seen some customers running them in the cloud when latency was within what is required (it is basically just a small VM that is added as a host to the vCenter in use by the vSAN).

    Redundancy and failover:

    In the simplest of terms, FTT=1 on an object (e.g. a vmdk - a hard disk from a VM) means that two copies (data components) of it are created, one is stored on each node (and a tiny witness component stored on the Witness), in the event of a failure of one copy (single-disk failure, disk-group failure or node failure) the VM can keep running from the remaining copy of the data component.

    However in the case of a node failure (Hardware failure, Power issue, PSOD etc.) the VMs on this how will go down but can be restarted/re-registered right away on the remaining host manually (or using HA if using Essentials Plus or higher and set-up to do this).

    I am aware that there is a substantial difference in cost between Essentials and Essentials Plus, there is also a lot of key features not in the latter (for this reason assumedly) and also the added benefit of support at a reasonable cost should you need/require to have it.

    On Dell 730s the controllers work in pass-through mode, no R1 or R0 at the disk-level. This 'Raiding' is handled down the line by vSAN using Storage Policies as discussed above - e.g. FTT=1 applied to a VM or its disks is basically a R1 - striping for performance is also applicable (so yes can be essentially R10, but this is applied at the object level not at the controller/physical disk level).

    I hope this helps clarify things and if nothing else to give you some insight into vSAN!

    Bob

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  • 3.  RE: vSAN in 2Host Cluster??

    Posted Apr 12, 2017 08:08 AM

    Hi Bob,

    Thx alot for your input, answered many of my questions. I just realized something If/when i go for a 2-Node Direct connect i need to have both hosts in the same rack in the same room to be able to use vSAN standard? As soon as i move one host to another physical room inside the gates for our factory it will be considered a stretched cluster?

    if budget is running tight i get the feeling that i should get vSAN first and then upgrade Essentials to Essentials Plus, since vSAN seems abit harder to implement later on an already running enviroment.

    Configuration: It will probaly be 3x600 or 3x800 SAS instead of the two 1.2TB SAS

    vSAN implementiation:  The planned VM's will without a doubt run on one of the hosts, it seems like the 2-Node Direct Connect setup will be the way to go for us. When it comes to the witness i can either run a seperate hardware for that (have a spare server thats not to old) since essentails will provide licenses for 3 hosts, or i will use witness appliances. in either case i need to put them in a seperate "witness cluster"?

    Br.

    Simon Sundkvist



  • 4.  RE: vSAN in 2Host Cluster??

    Posted Apr 12, 2017 08:39 AM

    I just realized something If/when i go for a 2-Node Direct connect i need to have both hosts in the same rack in the same room to be able to use vSAN standard? As soon as i move one host to another physical room inside the gates for our factory it will be considered a stretched cluster?

    The vSAN EULA states that in the case of a 2 node configuration you are allowed to have them in separate buildings or rooms, without the need for the Enterprise license. In other words, this would be fully supported and legal in a 2 node configuration when using "vSAN Standard".

    When it comes to the witness i can either run a seperate hardware for that (have a spare server thats not to old) since essentails will provide licenses for 3 hosts, or i will use witness appliances. in either case i need to put them in a seperate "witness cluster"?

    Note that you will need to run this in a 3rd location when you are stretching the other two nodes across locations



  • 5.  RE: vSAN in 2Host Cluster??

    Posted Apr 12, 2017 12:13 AM

    Another thing which our sales-team or vendor-partner might be able to provide better information on:

    ROBO might be cheaper here vs 2-node Direct Connect set-up as ROBO is licensed per pack of 25 VMs (so maybe 1 vSAN license for the 2-data nodes vs 2 vSAN licenses)

    https://blogs.vmware.com/virtualblocks/2015/09/11/vmware-virtual-san-robo-edition/

    Don't quote me on this though as I don't typically deal with that side of things (I am the guy that resolves the situation when someone inadvertently gets their hardware immersed in water and wants their Prod VMs to be happy again :smileygrin: )

    Bob

    -o- If you found this comment useful please click the 'Helpful' button and/or select as 'Answer' if you consider it so, please ask follow-up questions if you have any -o-



  • 6.  RE: vSAN in 2Host Cluster??

    Posted Apr 25, 2017 08:21 AM

    I've been considering a two-host vSAN cluster for my environment a while ago with almost the same constraints you've got. Unfortunately, I could not afford a proper third host for stretched cluster and the pricing tag for the vSAN licensing was out of my budget. I've gone with StarWind VSAN StarWind Virtual SAN® – VSAN Storage Cost for ROBO and SMB  instead. It does exactly the same what vSAN does at a lower price but what was even more crucial for me - they are totally OK with only two hosts (directly connected over 10 Gbe) switchless. And since I had only SSDs in my physical servers, I could go all-flash without paying additional money for this feature. These guys also offer pre-built hyperconverged nodes (AFAIK DELL-based) which I am considering right now for my next purchase.