The default results of diskutil list
on a clean Lion installation should be as follows:
mac:~ me$ diskutil list
/dev/disk0
#: TYPE NAME SIZE IDENTIFIER
0: GUID_partition_scheme *500.1 GB disk0
1: EFI 209.7 MB disk0s1
2: Apple_HFS Macintosh HD 499.2 GB disk0s2
3: Apple_Boot Recovery HD 650.0 MB disk0s3
My definition of a "clean install of Lion" involves letting Disk Utility from the installer partition the drive as GUID and telling it to use all space as a single partition.
Furthermore, your disk0s1 / EFI partition shouldn't show as partitioned according to disk utility:
mac:~ me$ diskutil info disk0s1
Device Identifier: disk0s1
Device Node: /dev/disk0s1
Part of Whole: disk0
Device / Media Name: EFI system partition
Volume Name: Not applicable (no file system)
Mounted: Not applicable (no file system)
File System: None
Partition Type: EFI
OS Can Be Installed: No
Media Type: Generic
Protocol: SATA
SMART Status: Verified
Total Size: 209.7 MB (209715200 Bytes) (exactly 409600 512-Byte-Blocks)
Volume Free Space: Not applicable (no file system)
Device Block Size: 512 Bytes
Read-Only Media: No
Read-Only Volume: Not applicable (no file system)
Ejectable: No
Whole: No
Internal: Yes
Solid State: No
Since your mac will boot, it may be overkill to erase everything and start over, but your EFI partition is hitting a check that Apple built into the Disk Utility, so do know that future updates could have problems and you might be forced to re-do things at a time less convenient if the difference between your system and an expected / Apple generated EFI actually breaks something Apple changes down the road (or when certain expected conditions arise like a firmware password, etc...).
On the flip side - it could be a simple check to alert you of a non-standard EFI and not that your EFI is in some way ever going to break. Can another vendor support your Microsoft EFI? If so, you might be able to leave it as is since it appears you are clearly using tools designed to make proper changes even if Disk Utility isn't able to guarantee the changes are appropriate.
You're on the right track with 9-10GB if you're doing a barebones OS X install. See the OS X Mavericks requirements. However...
If you're keeping the root /Applications on the same volume as the OS, then you might want to leave additional space if you plan on adding applications to the system. I've never tried to store /Applications on a separate volume from /System (the OS) and /Library (system-wide preferences, support files, etc.), but might be worth a shot if you have time to experiment.
My only concern would be disconnects between core OS X applications and their supporting frameworks. A prime example would be something like "DVD Player."
Best Answer
As mentioned by the other comments, Apple's default partition scheme is to have everything on ONE partition. While not recommended (potentially due to not being easy to do), it is possible to move a home folder to a different partition.
Here is how:
root
into the username field and supply the password you just gave it/Volumes/<volume_name>
resetpassword
and hit EnterIf this is working for you as expected, here is the clean-up:
In case it is not working (though I would understand that it will), you can use root to log in and move the home directory back to where it was using System Preferences > Users & Groups > Advanced Options (right-click on that user).
I hope this guide helps.