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prab4th
Asked: 2015-12-05 09:51:22 +0800 CST

If I'm reinstalling ubuntu, would there be a problem if I installed with uefi enabled. Previous installation was installed with csm

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I'm reinstalling ubuntu 15.10 because I feel as if it's slowing down (I installed gnome-shell along with unity and it hasn't been the same ever since)

And the current config was installed with 'csm' boot config. And if I installed over the current one with uefi enabled would there be a problem.

Model: ATA TOSHIBA MQ01ABF0 (scsi)
Disk /dev/sda: 976773168s
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start       End         Size        Type      File system     Flags
 1      2048s       968624127s  968622080s  primary   ext4            boot
 2      968626174s  976771071s  8144898s    extended
 5      968626176s  976771071s  8144896s    logical   linux-swap(v1)
boot

2 Answers

  1. Best Answer

    Given that your disk currently uses MBR partitioning (Partition Table: msdos in your parted output), it's safest to stick with BIOS/CSM/legacy-mode booting. Generally speaking, for a single-OS installation, there's little advantage to be had for booting in one mode vs. the other. If you have a specific reason to want EFI-mode booting, please say what it is.

    If you want to switch to EFI-mode booting, you (pretty much) have to switch from MBR to GPT. This can be done dynamically with gdisk; see this page for details. This may require some additional re-partitioning, though -- in particular, booting in EFI mode requires an EFI System Partition (ESP), which your disk doesn't seem to have at the moment.

    Your partition table doesn't seem to show a separate /home partition, so preserving /home will require backing up your current /home and then restoring it when you're done. OTOH, maybe I'm missing something -- which brings me to....

    For future reference, whenever somebody asks for program output, please either edit your original question or post it to a pastebin site and provide a link to your document there. Pasting program output into a comment causes the formatting to go all wonky, as you've seen. That makes it harder for the people who are trying to help you. (We're all volunteering our time.)

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  2. Unless you have multiple operating systems running, reinstalling Ubuntu in EFI mode won't make any issue. Since your disk uses MBR partitioning scheme you should first convert it to GPT. However MBR-to-GPT conversion could sometimes leave gaps because of alignment policies.

    Next time you partitioning also consider LVM

    Since you don't seem to have a separate /home partition consider backing up any important files there.

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