I have a mid-2012 3.2 GHz quad-core Mac Pro with 12 GB RAM, 1 TB system drive and 2 TB drive for VMs. I'm currently running Mavericks and Fusion 6.0.4. The host OS and all applications are installed on the system drive. All VMs and folder that is shared with all VMs are located on the 2TB drive. I typically have two VMs running simultaneously and sometimes want additional VMs running simultaneously. One VM is always 64-bit Win 7, 1 GB RAM, 1 processor, used for running Microsoft Office. All other VMs are different version of Windows, typically 64-bit Win 7, typically 2-4 GB RAM, used for C++ development in Visual Studio. Because the product I develop supports multiple versions of the host product, ESRI ArcGIS, I have a large collection of VMs for different versions of ArcGIS. Most VMs are less than 50 GB in size, all are less than 100 GB. I'm generally happy with performance when running only the Microsoft Office VM and one ArcGIS VM. However, when I launch a second ArcGIS performance often comes to a crawl, even when one VM is being used to merely edit source code and the other to compile and link, and does not improve when one of the VMs is suspended or shut down. The slow down doesn't start the moment I load the third VM, but seems to start once one or the other is loaded up with a compile or something. To return to normal it seems necessary to restart Fusion.
So, I have the opportunity to perform some modest upgrades to my system. A primary goal is to improve performance when running three or more VMs. The obvious upgrade is to bump the RAM up to 16 GB using a 4-4-4-4 configuration instead of the current 4-4-2-2. The other seems to be an SSD, but I'm uncertain as to how and how effective would it be? I know SSDs typically accelerate system boot and application launch times, neither of which are of much concern to me. I'm more concerned about slow downs in compiles, links and Visual Studio's Intellisense. I can't afford a 2 TB SSD, even if those exist. Looking at prices, 100-200 GB is more likely. I am using about 100 GB of the 1 TB system drive, so replacing this with an SSD or a Fusion drive should be possible. But will that help with the specific performance issues I'm seeing? Is it more likely my issues are the result of swapping on the system drive, or I/O to the drive hosting all the VMs? If the former then replacing the system drive with an SSD seems the way to go. If not, then I'm not sure there's any way an SSD could help. Maybe hosting the VMs of a RAID array instead of a single drive?
TIA for any advice.
Alan