Is 8GB RAM needed for MB Air i7 with 4GB RAM and large Fusion file?

[Appleconsumer]

I'm considering a 4GB 11" MacBook Air with i7 processor and 4GB RAM.  My VMWare Fusion folder is now about 90GB, and I now allocate 1 core and 1536GB of RAM to the VM, on a 4GB MacBook Pro from 2008.  Currently, it's not snappy when running Mac and VM apps.  In the Activity Monitor, (a) I have 80MB Free, 1.96GB Wired, 1.36GB Active, and 615MB Inactive, (b) my VM size is 210GB, and (c) I generate 350MB Page ins, 270MB Page outs, and 190MB Swap used over the course of 4 hours of usage.

I'd appreciate your thoughts on whether 4GB RAM on a MB Air will probably be enough (there's no option on the Air for 8GB, only on the heavier new MacBook Pros).  I'm not sure how much the i7 hyperthreading will help.  Surely, the SSD will help, but I don't know how much.  One way to look at the SSD might be at 200MB/second speed of the SSD, the cumulative total of Page ins or outs is only about 1 second over 4 hours -- not much of a sacrifice, but I don't know if this thinking is correct.

Thanks in advance for any of your input!

[Appleconsumer]

Forgot to mention, if it's any use -- my vmware-vmx file in the Activity Monitor weighs in at 1.68GB at the moment, but has been as high as 2.3GB.  I have no idea why it's so large or why the size changes significantly from time to time.

Thanks again!

[WoodyZ]

What Guest OS is running in the Virtual Machine?

[Appleconsumer]

It's now running XP, but in about a month it will be changed to Windows 7.

[WoodyZ]

Forgot to mention, if it's any use -- my vmware-vmx file in the Activity Monitor weighs in at 1.68GB at the moment, but has been as high as 2.3GB.  I have no idea why it's so large or why the size changes significantly from time to time.

Just an FYI...  Aside from the VMware Fusion application and it various background program files that are using memory, the vmware-vmx process it the actual Virtual Machine and its initial size is in part based on what Guest OS is running and how much RAM it is assigned plus either an addition 128 ~ 256 MB for RAM used by the virtual graphics adapter.

So you say you've assigned "1536GB of RAM to the VM" and it's Windows XP so add another 128 MB to that and the base memory footprint is 1664 MB and if that was Windows 7 with the same amount of RAM assigned it be plus 256 MB or a base memory footprint 1792 MB and it can go up from there depending on what sort of activity is going on in the Virtual Machine.

[admin]

'I now allocate 1 core and 1536GB of RAM to the VM'  now the VM is XP, will be Windows 7. You currently don't find the solution to be snappy.

Based on that, I'd say you need to give the VM at least 2 GB, and yes, Fusion will use more than that. Depending on what you are running in the Windows 7 VM, you might need more (or less, the minimum is much less). Just treat the VM as a piece of Windows hardware, with regard to how much virtual RAM to give it. Giving it much more than it needs (check Task Manager from within Windows) is not good, either.

SSD will certainly help!  They are fantastic for Fusion and VMs in general.  For example I can even run an XP VM acceptably on a 1st generation Mac Book Air with low RAM.  The slow processor is substantially rescued by the SSD (it is a little slow, though, don't get me wrong).

A MacBook Air with an i7 and SSD should be very fast for running a VM.   As for 4 vs 8 GB RAM, if there is no possibility of upgrading it later, and it was not too exorbitantly priced, I'd buy 8 GB, if you can. UNIX loves RAM!

Not sure how long you keep the machine, but, in general, software won't be getting any smaller.