(solved)Virtual machine fedora does not boot, please help~~~

[Kurin]

I have been running fedora 12 as a virtual machine on a Windows 7 (64bit) host through VirtualBox.
Since the fixed size of the VDI file for fedora is only 10g, much more space is needed now for software deployment..
in fedora I usually install programs using yum install and it is generally not easy and straightforward to modify the installation folder. So it is desirable to simply enlarge the VDI size. Since the vdi was created with a fixed size,
after some research I found a way to implement resize (enlarge). It was a method that first creates a new vdi with
intended size (64G), then copies all partitions from current smaller vdi to the new vdi. So everything on the new vdi should be exactly the same as the old one. but now the new machine does not boot. What am I missing? Thanks in advance.

[stefan.becker]

Maybe new disk has a new UUID and you mount partitions with kernelnames and not with devicenames like /dev/sdaX.

[Kurin]

Maybe new disk has a new UUID and you mount partitions with kernelnames and not with devicenames like /dev/sdaX.

no, the new partitions have the same uuid as the old ones, as shown below, sda1-3 are copied to sdc1-3.
and in they are mounted by uuid in /etc/fstab

/dev/sda1: UUID="b81a489e-50af-4546-bbcb-3b25254adc98" TYPE="ext4"
/dev/sda2: UUID="30b58cd2-eec2-4ba9-828e-239b6577f465" TYPE="ext4"
/dev/sda3: UUID="f37019af-06ff-4e88-a1bb-8a65b12113ba" TYPE="swap"
/dev/sdb1: LABEL="/intelstudio" UUID="42d28d79-adf2-480b-a44f-75c3d86fec41" TYPE="ext4"
/dev/sdc1: UUID="b81a489e-50af-4546-bbcb-3b25254adc98" TYPE="ext4"
/dev/sdc2: UUID="30b58cd2-eec2-4ba9-828e-239b6577f465" TYPE="ext4"
/dev/sdc3: UUID="f37019af-06ff-4e88-a1bb-8a65b12113ba" TYPE="swap"

now the virtual machine still boots from the old vdi: sda but I want to boot from sdc.

[Kurin]

the system works again after a grub reinstall.