Hi,

I have a wierd problem. WinPE5.0 image do not boot once the size of the ISO exceeds ~1 GB. I am seeing this behaviour on  x86 based ISO, havent tried it on x64 yet.

When the size is less than 1 GB the ISO boots, I then copied some more files to the ISO to make its size exceed 1 GB and it don't boot. Any know issue with WinPE?

Is there any limit to the .wim file size?

Can someone please help me understand this behaviour.

Thanks in advance.

IIRC there is no upper limit to wim size for WinPE. However, understand how WinPE works, it runs itself from a RAMDISK. So the larger your wim is the more RAM is required to run it.

Hi,

I just make an supplement, Since Windows PE RAM Disk requires an active partition with a size no less than the size of your Windows PE image. However, according to the contents of the link below:

Virtual RAM Drive Emulator supports a maximum size of 1024MB on your RAM disk. 

See: https://technet.microsoft.com/en-us/magazine/gg132831.aspx

This should could be explain why WinPE size couldn't be larger than 1GB.

Hi Tripredacus and Roger,

Yes, it looks like there is no limit to the size of WinPE image. As I am able to create x64 based ISO of 1.7GB and it boots perfectly well with 3GB RAM.

If RAM drive size was the issue then it would be there for x64 too. Looks like there is something else leading to failure for x86.

Thanks

The RAM problem does happen in x64 as well. My wonder is why your PE is so big to begin with. The largest one I have is 276MB, WinPE5 x64 and has a minimum RAM requirement of 1GB and on some configurations something just over 1GB.

I have installed powershell, .net, .wmi and other packages, which makes the wim size 500MB+. In addition I have some other binaries that I want to used after the OS comes up.

I am wondering why the wim size is affecting the boot. I am observing the boot failure only when the wim size is going above 900MB.

You need to know what your actual footprint is. Most WIM file are compressed. When you boot to a WIM, everything gets uncompressed and put into memory to run.