how to fix disk partition which is not in order?

Posted by daygamer77@reddit | linuxadmin | View on Reddit | 9 comments

Hi,

How do you fix this setup

Device       Start       End   Sectors   Size Type
/dev/sda1     2048      4095      2048     1M BIOS boot
/dev/sda2     4096    208895    204800   100M EFI System
/dev/sda3 1257472 536870878 535613407 255.4G Linux LVM
/dev/sda4   208896   1257471   1048576   512M Linux extended boot

As you can see it seems that /dev/sda4 should be /dev/sda3

I am planning to add space on the root partition which is currently on /dev/sda3

Thanks

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bufandatl@reddit

Order doesn’t really mean anything. Except for bios boot and EFI they should come at first. The rest isn’t really important since they are used by path or UUID anyway and not their „drive letters“.

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hrudyusa@reddit

This. Unfortunately , Linux re-enumerates the drives each time it boots, so if you add additional drives and/or controllers even the drive letters will change. Which is why they use UUIDs or labels in /etc/fstab. If you are using Logical Volumes, then the drive letters and partition numbers become moot because all that is abstracted.

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michaelpaoli@reddit

Pretty dang easy, e.g. (I used loop1 to test/check, backed by sparse file, my comments on lines starting with "//"):

# fdisk /dev/loop1
// ...
Command (m for help): p
// ...
Device         Start       End   Sectors   Size Type
/dev/loop1p1    2048      4095      2048     1M BIOS boot
/dev/loop1p2    4096    208895    204800   100M EFI System
/dev/loop1p3 1257472 536870878 535613407 255.4G Linux LVM
/dev/loop1p4  208896   1257471   1048576   512M Linux extended boot
// ...
Command (m for help): x

Expert command (m for help): m
// ...
   f   fix partitions order
// ...
Expert command (m for help): f
Partitions order fixed.
// ...
Expert command (m for help): r

Command (m for help): w
// ...
# fdisk -l /dev/loop1
// ...
Device         Start       End   Sectors   Size Type
/dev/loop1p1    2048      4095      2048     1M BIOS boot
/dev/loop1p2    4096    208895    204800   100M EFI System
/dev/loop1p3  208896   1257471   1048576   512M Linux extended boot
/dev/loop1p4 1257472 536870878 535613407 255.4G Linux LVM
#

Note that the kernel may not immediately pick up the change (because in use), however, should be able to read and see the changes easily enough on the drive itself.

Also, if you've got stuff using/referencing the (soon to be old) partition numbering, you may need to correct that to avoid issues/pain, but all should be fine once any such reconfigurations are completed, and reboot is completed. E.g. you may have to tweak EFI configuration, GRUB configuration, /etc/fstab configuration. But hopefully in most cases you're using UUID, rather than partition #, so hopefully few to zero configuration changes need be made.

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daygamer77@reddit (OP)

thank you so much for the response and all the explanation, really appreciate it, its really helpful

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chock-a-block@reddit

You need to write a udev rule to force the name to be what you want. Pretty sure this opens a can of worms for you.

Your other choice is to make aliases for all the partitions..

[-]

deeseearr@reddit

Do not mess with that partition table. Partitions 1 and 2 look like your EFI boot partitions, 4 is the /boot partition and everything else is in LVM. Renumbering them will only bring you pain.

If you need to add space to the root partition you just need to add more disk space to the Volume Group it is in. The easiest way to do that is to add a new disk then add it to the same volume group, and then you will be able to extend any of the logical volumes in there.

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daygamer77@reddit (OP)

Hi thank you for the response, do you mean I will have no problem if i just extend or add space on partition 3 which is /dev/sda3, considering that there is /dev/sd4 after it?

I am thinking it will have no problem because the end sector is on /dev/sda3.

[-]

deeseearr@reddit

If this is a virtual disk and you can just extend it by adding sectors after 536870878. Any empty space would be after sda3 so you could just extend that. The partition numbers don't mean anything.

If you're not sure what you're doing then the safest approach is to add a whole new disk, add it as a physical volume and put that in the existing volume group. That will give you additional space with no risk of messing up the first disk, be easier to do, and the end result will be exactly the same -- more space in the volume group which you can use to extend your logical volumes.

Or it is better to add new disk, and add it to root volume group?

TL;DR: Yes, that's what you should do.

[-]

daygamer77@reddit (OP)

Thank you, I was able to expand /dev/sda3. Really appreciate the help specially the explanation. Thanks again