I’ve just finished my second installation of XP on my EeePc. The first time, I did it with my original Windows CD, separately loading SP1 and SP2. After SP2, I had run out of disk space – just about 100Mb remaining of my 4 gigs. Therefore, I manually created a Windows XP + SP3 CD via nlite, and viola! the whole thing takes just 1200Mb or so of disk space. The question is: why? It’s the same darn Windows that I’m installing, isn’t it?
Functionally, yes. But there’s a subtle difference.
Every time that you install a Windows patch, the files modified by that patch are backed up to a sub-folder of your %systemroot% folder (usually C:\Windows\ in the case of XP) so that the patch can be uninstalled later. The name of each subfolder will be something like “NtUninstallKB951698”. Each Windows Service Pack is basically just a collection of all the patches that have been released since the last service pack.
So when you install a service pack, to an existing installation, a whole bunch of backup dirs are made (unless they already exist because your system already had those particular patches installed). However, when you slip-stream a service pack into the original installation media, these folders aren’t created on the CD. A system installed from an SP3 disc can’t be rolled back to a pre-SP3 state, unlike a system that was installed and then patched.
The patch backup folders are compressed by default if Windows XP is installed on an NTFS volume (as opposed to FAT32, which you shouldn’t be using even if XP does allow it). They’ll show up in blue if you have the “display compressed files/folders in an alternate color” option enabled for Explorer. Still, they can take up quite a lot of space when you add them all up for 3 service packs.
There may also be a difference in the %systemroot%\ServicePackFiles\ folder. Normally, all of the binary files from the latest service pack are copied into this folder when you install the service pack, whether or not all of the individual files were actually installed to your system. The reason for this is that the service pack may include patches for Windows components that you don’t currently have installed. If at some point in the future you decide to install one those components, Windows needs to fetch the source files from somewhere. Normally this would be your Windows CD, but this won’t work right if your CD is older than your system’s current service pack level. So instead the files are loaded from the ServicEPackFiles folder first, and then from your CD if they aren’t located there. That way you don’t wind up installing old, unpatched versions of Windows components.
If your installation CD matches your system’s SP level (because you slipstreamed it), then this folder is unnecessary. I don’t remember whether or not the Windows Installer is smart enough to realize this, though. If it is, that would also account for some of the size difference.
When you install a new patch or service pack, I would recommend keeping its uninstall folder around for at least a few days until you’re sure that the patch isn’t going to screw anything up for you. If all is good, you can safely delete the NTUninstallKBxxxxxx folders to free up space as needed/desired. Do not delete the ServicePackFiles folder.
In any case, slipstreaming is a good idea even though you can work around the space issue. Unpatched Windows systems (especially pre-SP2) are very vulnerable to remote exploits until you have the latest service pack installed. You should always patch the system to the latest SP level before giving it any kind of internet access. The easiest way to do this is to install from a patched CD to begin with, and then connect it to the internet.
Did you notice that you can also eliminate a lot of unnecessary parts of an XP installation with nLite? You can choose to not even put things like the Indexing Service, Language packs, Games, etc. on the CD if you know you will not need them. If you do a bit of research to determine what you actually need you can make a very small installation.
Service Packs for XP are cumulative. You don’t need to install SP1 if you then install SP2, and you don’t need to install either if you are going to install SP3.
I did, and that was extremely helpful in this particular case. Saved me about 250MB of installation room, as I recall.
Stathol, thanks for the explanation! I noticed when I put SP1 on that that still had the option of disabling the backup – SP2 and 3 seem to be lacking that. Very annoying. GSV, that’s odd, because I tried to do SP3 first, and it said that some version checks failed to correspond to what the service pack expected and refused to update the system. Possibly there was some corruption during the initial Windows installation?
Apologies for my overconfidence. It seems MS does require at least SP1 to be installed before installing SP3. Technet article This is against the usual policy for Service packs, which ARE supposed to be cumulative.