Hello,

I have Fedora 17 and Scientific Linux 6.2 guest systems running under VirtualBox 4.1.18.

I read here that there is a way to shrink a guest machine's VDI hard disk image. However, its Linux guest instructions say that the method only works for ext3 filesystems. The article was written in 2009, probably why a method for ext4 was not mentioned. My virtual machines use ext4.

Is there a way to effectively shrink my Linux guest VDI in VirtualBox, perhaps similar to the method described in the linked article?

Thanks!

It states it doesn't work for ext4, so it was at least considered - maybe even tested.

Perhaps try just creating an empty (as in /dev/zero) file of sufficient size using "dd" then delete it. Then try the compact.

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OK, I think I will try your suggestion and just take advantage of /dev/zero. However, the RHEL documentation (I presume it will work for Scientific Linux 6.2, and more or less for Fedora 17??) said there are three "recovery modes": rescue, single-user, and emergency.

Do you know which one is more appropriate for this attempt? I guess probably not single-user mode, because the documentation said "it does not give you the option to mount the file systems as read-only or not mount them at all" (from here). What about the other two?

Thanks!

Sorry, this thread got "lost" in my mail.
I don't understand your question. Log into the relevant guest, create a "big" zero-fill file, then delete it. Do it from a "normal" user should suffice I would think.
Shut the guest down, and try the compact run on the inactive guest.

Sorry about the confusion, what I meant was that the original instructions I saw (in the linked blog post from my original post), it said I should zero-fill my virtual hard disk inside the guest Linux system's recovery mode (instead of logged in as normal user).
Therefore I was wondering *which* recovery mode I should boot the guest system into, because RHEL/Fedora has *three* different recovery modes...