For a very long time, iSystems offered only limited support for Evolution instances running in a virtual environment due to concerns about performance or configuration. After having seen some very poor VM installations in the past, I understood this.
But this has not been the case in years; Evolution works great in a properly-configured virtual machine, especially on the Windows side, and customers have used both VMware and Hyper-V very successfully.
The classic SaaS environment built by iSystems was entirely VM on the Windows side, and in the current AWS pods, all parts (db and middle tiers) are virtual.
If a customer is purchasing new gear to host more middle-tier resources, I always recommend getting a good solid machine with SSD storage, plenty of RAM, and to split it into VMs of 8 CPU each; a 24-core machine would conveniently host three VMs.
Evolution is still a 32-bit program with a two gigabyte per-process memory limit, and it runs only as many tasks as there are CPU cores. Though technically it can use all 24 cores of a big machine, all 24 concurrently-running tasks have to fit in that limited 2 gigabyte memory space, and it's very, very common to run out of memory if the mix of jobs just happens to go over the 2G limit. This is painful.
In practice, bureaus with memory issues have to artificially lower the max-tasks that Evolution will run at one time. This alleviates the memory issue, but everybody hates it that a 24- or 32-core machine is only using 8 of them for Evo. What a waste!
But turning this same machine into three VMs - of 8 cores each - then you now have three request processors and three separate 2 gigabyte process limits, and it can well and truly use all the power of the machine.
The Linux DB server requires much more thought, as Evo will actually use a very very powerful machine without the artificial 32-bit process constraints that limit the middle tier.
Most customers are no longer purchasing new gear for their self-hosted Evolution instances, as they're planning to move to an AWS pod sooner or later, but those doing a hardware refresh may well wish to consider going the VM route, especially if they're a VM shop already.
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