12.04 LTS PAE Advice?

[frogotronic]

Hello,

I have a question regarding the PAE kernels. I am currently on a laptop with 8 GB RAM and using the 32 bit 12.04 LTS, which installed the PAE version of the kernel (3.2.0-26-generic-pae). Apparently Linus Torvalds no longer wishes to support PAE kernels (http://cl4ssic4l.wordpress.com/2011/05/24/linus-torvalds-about-pae/).

Question 1: Will the PAE kernel continue to be updated for 12.04 LTS by Ubuntu; or should I backup my data & scrap my drive and install the AMD64 version as soon there will no longer be updates of the PAE kernel available? In other words, will I fall behind in having installed the PAE version of the kernel relative to the AMD64 variant?

Question 2: Is the PAE kernel being simply incorporated in the "generic" kernel, so that eventually, there will be an upgrade from PAE=>Generic, and yet the Generic will handle the duties of the PAE?

Thanks,
CH

[dino99]

you also can install newer kernel like 3.4 or 3.5

https://launchpad.net/~ubuntu-x-swat/+archive/q-lts-backport/+index?field.series_filter=quantal

[frogotronic]

you also can install newer kernel like 3.4 or 3.5

https://launchpad.net/~ubuntu-x-swat/+archive/q-lts-backport/+index?field.series_filter=quantal

which will address the extra memory?

Sorry being obtuse, my grasp of kernels is very simplistic

[oldfred]

No you really want to install the 64 bit verison, but that will require you to backup /home and any other custom systems in /etc and erase the 32bit version.

Ubuntu was going to stop supporting the non-PAE version for really old computers. I think that is still available in Lubuntu or Xbuntu.

Also part of the reason most of us in the forum did not understand why Ubuntu kept recommending the 32 bit version. It seems they found many users were older systems and figured those with 64 bit systems would know to install the 64 bit version.

Why Ubuntu officially suggests 32bit (25% have 32bit systems)
https://lists.ubuntu.com/archives/ubuntu-devel/2012-April/035088.html

Shows some of the performance loss you get with PAE even back in 2009:
Essentially says if you can use the 64bit kernel you should.April 2011
http://www.phoronix.com/scan.php?page=article&item=ubuntu_natty_pae64&num=1
https://help.ubuntu.com/community/32bit_and_64bit
Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks Dec 2009
http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1

[frogotronic]

No you really want to install the 64 bit verison, but that will require you to backup /home and any other custom systems in /etc and erase the 32bit version.

Ubuntu was going to stop supporting the non-PAE version for really old computers. I think that is still available in Lubuntu or Xbuntu.

Also part of the reason most of us in the forum did not understand why Ubuntu kept recommending the 32 bit version. It seems they found many users were older systems and figured those with 64 bit systems would know to install the 64 bit version.

Why Ubuntu officially suggests 32bit (25% have 32bit systems)
https://lists.ubuntu.com/archives/ubuntu-devel/2012-April/035088.html

Shows some of the performance loss you get with PAE even back in 2009:
Essentially says if you can use the 64bit kernel you should.April 2011
http://www.phoronix.com/scan.php?page=article&item=ubuntu_natty_pae64&num=1
https://help.ubuntu.com/community/32bit_and_64bit
Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks Dec 2009
http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae&num=1

Thanks for this answer - Seeing as I've just installed 12.04 LTS a week ago, I think I'm going to go to the effort of backing up my home directory again and going with the 64 bit version. I'm running a laptop with 8 GB memory, so I should see a significant improvement with the AMD64 kernel on this machine. Previously, when I ran laptops/desktops with 2 GB of memory, I really didn't bother.

Regards,
CH

[darkod]

Thanks for this answer - Seeing as I've just installed 12.04 LTS a week ago, I think I'm going to go to the effort of backing up my home directory again and going with the 64 bit version. I'm running a laptop with 8 GB memory, so I should see a significant improvement with the AMD64 kernel on this machine. Previously, when I ran laptops/desktops with 2 GB of memory, I really didn't bother.

Regards,
CH

You can also use this occasion to move to a separate /home setup. Calculate from your current system how much you need for / and /home, and install the new 64bit with separate /home partition. (You will need to use the Something Else option for that).

Copy the data back into /home just the same (only this time /home is actually a different partition).

During future clean installs, you don't even bother copying /home, you simply attach the existing /home partition. Of course, this doesn't mean you shouldn't make backups of your data on regular intervals. :)

[frogotronic]

You can also use this occasion to move to a separate /home setup. Calculate from your current system how much you need for / and /home, and install the new 64bit with separate /home partition. (You will need to use the Something Else option for that).

Copy the data back into /home just the same (only this time /home is actually a different partition).

During future clean installs, you don't even bother copying /home, you simply attach the existing /home partition. Of course, this doesn't mean you shouldn't make backups of your data on regular intervals. :)

Will I have to do anything to *link* the new separate /home partition to my new install, or will it do it automagically?

Thanks,
CH

[darkod]

Right now, the process would go like:
1. Boot the current system and copy everything you need from Home and all other folders where you might have your data.
2. Boot with the 64bit CD and start the install, select the Something Else method. That will show list of all partitions on the disk.
3. Delete all of them (easier) one by one, and create the following three:
root partition, primary, filesystem ext4, size 15-20GB (or more depending on current use), mount point /
/home partition, logical, ext4, size all the rest - determined swap size, mount point /home
swap partition, logical, use as swap area, size 2GB or 1.5 x RAM if you plan to hibernate, no mount point
The bootloader goes to /dev/sda. That's it.

Note that when I say delete all partitions above, I assume you are running only ubuntu since you didn't mention windows. If you do have dual boot, you will delete only the ubuntu partitions of course, not windows too. In that case create all three partitions as logical, it's usually better.

After you finish the install you will copy back your data into Home of the new installation.

In any future clean install, you will use Something Else again, but this time DO NOT delete any partitions. The installer marks all partitions as not used by default, to avoid using them wrongly.
So you will need to select them one by one, click the Change button below, and change the Use As from 'do not use' into ext4 for / and /home and swap area for swap. You set the correct mount point for / and /home and you tick the format box for / but you make sure you DO NOT tick the format box for /home.

That will format only / so it can make a clean install, but it will not format /home thus leaving all your data there. And you will always need to create the user during the installation the same as in the first install. You can add more users after the OS is installed. Their Home folders are kept too.

[frogotronic]

Right now, the process would go like:
1. Boot the current system and copy everything you need from Home and all other folders where you might have your data.
2. Boot with the 64bit CD and start the install, select the Something Else method. That will show list of all partitions on the disk.
3. Delete all of them (easier) one by one, and create the following three:
root partition, primary, filesystem ext4, size 15-20GB (or more depending on current use), mount point /
/home partition, logical, ext4, size all the rest - determined swap size, mount point /home
swap partition, logical, use as swap area, size 2GB or 1.5 x RAM if you plan to hibernate, no mount point
The bootloader goes to /dev/sda. That's it.

Note that when I say delete all partitions above, I assume you are running only ubuntu since you didn't mention windows. If you do have dual boot, you will delete only the ubuntu partitions of course, not windows too. In that case create all three partitions as logical, it's usually better.

After you finish the install you will copy back your data into Home of the new installation.

In any future clean install, you will use Something Else again, but this time DO NOT delete any partitions. The installer marks all partitions as not used by default, to avoid using them wrongly.
So you will need to select them one by one, click the Change button below, and change the Use As from 'do not use' into ext4 for / and /home and swap area for swap. You set the correct mount point for / and /home and you tick the format box for / but you make sure you DO NOT tick the format box for /home.

That will format only / so it can make a clean install, but it will not format /home thus leaving all your data there. And you will always need to create the user during the installation the same as in the first install. You can add more users after the OS is installed. Their Home folders are kept too.

I have only Ubuntu (run WinXP as VB if needed)

I'll need 16 GB SWAP (hibernate 8GB RAM)

Q1) bootloader on device sda & would be the root "/" partition? (like here: http://imgur.com/a/rw1r2#10 )

Q2) and the installer will recognise the "/home" as the location of the home directory?

- Thanks

[darkod]

I have only Ubuntu (run WinXP as VB if needed)

I'll need 16 GB SWAP (hibernate 8GB RAM)

Q1) bootloader on device sda & would be the root "/" partition? (like here: http://imgur.com/a/rw1r2#10 )

Q2) and the installer will recognise the "/home" as the location of the home directory?

- Thanks

A1. bootloader on sda which is the MBR of the disk, like on your pic. Not on sda1 which is the root partition. Bootloader always goes to the MBR since that is where the booting process starts.
A2. Correct. The beauty of linux is that it's working with mount points, not partitions. It couldn't care less what you use. By setting the mount point as /home, you tell it where to look for /home. For the OS, the location for the Home directory for all users will be sda3, but from "inside" you can't even notice it. The path is /home the same as it would be if it was only a folder on / (without separate /home partition).

EDIT PS: 16GB swap might be overkill, but if you can spare that space on the hdd go for it. Ubuntu boots fast enough for me so i don't even consider hibernation and I have 2GB swap which is not even getting used at all. 16GB might be a real waste of space, except for the hibernation process.

[oldfred]

Just to reinforce Darko's comments.

Your screenshot is a VM install so the install to sda it really to a MBR of the VM, but otherwise yours will be the same.

Also the screenshot shows /home being formated. That is correct if you are just creating it, but once you have data in it, then you would never check the Format as that would erase your data.

Screenshot also shows a small / of 5 to 6GB. I normally suggest 10 to 25GB as you need some space. I use about 7GB in a 25GB / (root) partition with lots of applications installed.

[frogotronic]

@oldfred

Understood.

Installed and now copying over my /home

That was SO easy, I can't believe I didn't do it sooner

I made 30 GB for the /, 16 GB SWAP, and 4XX GB for the /home

- CH