How much VM overhead? 2

[MasterRacker]

I have a ESXi host connected to an iSCSI SAN. On the SAN I created a 512GB volume that I connected to as a datastore in VMWare. VMWare sees it as a datastore with 511.75GB capacity. I created a 511GB virtual machine (2 MB block size) and that went fine. However, when I try to boot the VM to install the OS I get Insufficient disk space on datastore*.

This would seem to tell me that I need a little smaller VM to leave some slack for overhead. My question is how much?

Jeff
[small][purple]It's never too early to begin preparing for [/purple]International Talk Like a Pirate Day
"The software I buy sucks, The software I write sucks. It's time to give up and have a beer..." - Me[/small]

 

[Roadki11]

It wants the space to write out the .vswp file, it will be about the same size as the amount of ram you allocate to the VM. But I would leave a gig or so more than that even to leave room for log files and such.

RoadKi11

"This apparent fear reaction is typical, rather than try to solve technical problems technically, policy solutions are often chosen." - Fred Cohen

 

[eritguy]

If you plan on doing snapshots, suspends, etc, leave tons more, like around 20 to 100 Gb of free space.
Also, if you have a cluster and migrate VM's from host to host, it basically copies the vswp file along side (I had problems migrating, but later found I could live migrate if I manually set dedicated ram, then it wouldn't create the vswp copy).
vSphere starts complaining when my datastores are utilizing more than 60% of the size.