Memory management with xp guests.

[marcgijsman]

Hi All,

Can anyone tell me how Memory is used by xp machines in an VDI environment. We have about 50 VD's running XP Prof. each with 1GB or 2GB RAM assigned.

When we boot all VD's the hosts use 80% mem (of 32GB each), guests report different mem. usage in the VI Client allthough they are not being used at the moment?

Can mem be released back to the esx host when it is not being used by the guest?

[nick_couchman]

First of all, I think each guest on ESX has about some amount of memory overhead (100MB or something like that), so take that into consideration. That aside, each XP machine will take up as much memory as the guest O/S requires, up to the amount of memory you've assigned to the guest. So, if you've assigned 1GB to each XP VM, it will take up 1.1 (or so) GB at most, maybe less than that. The guests tend to use their max when they first boot, then taper off as they settle down, until someone logs in and starts using them. The memory will be released back to the host up to a point when not used by the guests. I have VMs on ESX that are assigned 256MB of memory but only use 32MB of memory a lot of the time.

[marcgijsman]

Is there a way to force the XP guests to return the memory back to the host?

I"ve tried using a RAM management tool within XP but this does not help.

In our environment the xp-machines also give some memory back but very slowly and not nearly enough, max 50% of the assigned memory.

[TomHowarth]

one thing I would do is lower the amount of RAM you have assigned to the Guests. 512 is more than enough in the vast majority of cases.

[GBromage]

Marc, have you loaded the VMWare Tools onto the virtual XP boxes? The ESX memory sharing/balloon driver is what releases the memory back to the host.

The machines will use a lot of memory when they start up, on my systems they settle down once the boot is complete and the VMWare service loads.

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On a separate note, I've been running a test with users having 1Gb ram on their machines. They seem to be using about 600Mb tops at the moment. So, is it better to:

1) Set the machines to, say, 784Mb RAM; or

2) Keep it at 1Gb, trusting in VI3's memory sharing to keep everything playing nice?

Thanks for your input,

Greg