Arch Linux

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

LTS Kernel + remote server

Hi all,

I rent a dedicated server running archlinux on which I want to have the lts kernel so I installed it.

I do not have any physical access, only ssh, so I wanted to make sure it will reboot. Is there a way to check that the grub configuration is OK?

For now, my /boot/grub/menu.lst looks like this:

default=0
timeout=5

    title linux archlinux2009-08
    kernel /boot/bzImage-2.6.38.2-xxxx-grs-ipv6-32 root=/dev/sda1  ro
    root (hd0,0)

Yes, that's it but I obviously did not make the install and have no idea about how they manage this in the datacenter. So, to what should I change this?
It does not look as my arch home installation at all (no initrd line).

Any help would be appreciated

EDIT: maybe this could help (content of /boot )

bzImage-2.6.38.2-xxxx-grs-ipv6-32
lost+found
grub
System.map-2.6.38.2-xxxx-grs-ipv6-32
kernel26-lts-fallback.img
System.map26-lts
kernel26-lts.img
vmlinuz26-lts

Last edited by Rolinh (2011-06-03 09:00:11)

Ramses de Norre

Member

From: Leuven - Belgium

Registered: 2007-03-27

Posts: 1,289

Re: LTS Kernel + remote server

Add this for the LTS kernel:

title  Arch Linux LTS
root   (hd0,0)
kernel /boot/vmlinuz26-lts root=/dev/sda1 ro
initrd /boot/kernel26-lts.img

Also, consider using persistent block device naming for your partitions to avoid a kernel panic during boot when the device nodes for your partitions get swapped. I encountered this once at work and it was a pain to have to go to the server room and fire up a live disc.

So give your root partition a label, e.g. root, and change the kernel line to

kernel /boot/vmlinuz26-lts root=/dev/disk/by-label/root ro

And do this for all partitions in fstab as well.

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Thanks for your answer .  On my laptop, I just use the UUID as so:

# (0) Arch Linux
title  Arch Linux
root   (hd0,6)
kernel /vmlinuz26 root=/dev/disk/by-uuid/4d3a1122-5177-4556-9740-0e23e57a8643 ro vga=0x0365
initrd /kernel26.img

I was told it is the best way to do.

I think this is weird

bzImage-2.6.38.2-xxxx-grs-ipv6-32

Why the ipv6 in the name? and those xxxx ?

And, I repeat my first question: how to be sure it will boot? Because if it does not, I will loose control of my machine

Ramses de Norre

Member

From: Leuven - Belgium

Registered: 2007-03-27

Posts: 1,289

Re: LTS Kernel + remote server

Using UUIDs is perfectly fine too, I just prefer labels because they are a lot more readable, less error-prone when copying (you can spot a typo or missing character) and they don't have to change when you change your physical partition layout.

The name of the kernel image has no reason, whoever made the image decided to use that name for some reason.

For your first question: I do not know of any fail-proof mechanism to assure you the machine will boot... Trying out a new kernel _can_ lead to problems and I don't think you can be sure that it works without trying it out. If you absolutely cannot afford to gain physical access to the server or get someone else there, you shouldn't change kernels.

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Again, thanks for your reply.

If you absolutely cannot afford to gain physical access to the server or get someone else there, you shouldn't change kernels.

I will never be able to have physical access nor someone I know as the server is in a datacenter in some place I do not know. If it fails, I will have to ask the hosting provider to reinstall the server and, beside having to reconfigure all the services running on my server, I will have to pay for this.

So, I will just stick with the current kernel for now but... there should be a way, no? This is a pretty common situation.

tomk

Forum Fellow

From: Ireland

Registered: 2004-07-21

Posts: 9,839

Re: LTS Kernel + remote server

Of course there's a way - it's called KVM access (Keyboard/Video/Mouse).

Of course, you would first have to see if your datacenter provides it, and then you would presumably have to pay for it.

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Ok, I did not know about KVM access until now.
It is 49€ for installing KVM + 29.99€ to rent it for a month.
So... I will forget about the LTS kernel I guess...

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Well, finally, it seems that I can use a rescue mode to boot on some other kernel the hosting provider has using a netboot. So, I will just try and see what happens.

Last edited by Rolinh (2011-06-03 19:23:28)

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

All right. I modified my /boot/grub/menu.lst as follow:

default=0
timeout=5

# original setup
#    title linux archlinux2009-08
#    kernel /boot/bzImage-2.6.38.2-xxxx-grs-ipv6-32 root=/dev/sda1  ro
#    root (hd0,0)

# kernel LTS
    title linux archlinux2009-08
    root (hd0,0)
    kernel /boot/vmlinuz26-lts root=/dev/disk/by-uuid/9d3e0112-834d-42e7-9648-ace061722ed7 ro
    initrd /boot/kernel26-lts.img

Here is the output of fdisk -l

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes
255 heads, 63 sectors/track, 121601 cylinders, total 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00050a12

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        4096    20975616    10485760+  83  Linux
/dev/sda2        20975617  1952468992   965746688   83  Linux
/dev/sda3      1952468993  1953520064      525536   82  Linux swap / Solaris

And here is the output of ls -lF /dev/disk/by-uuid

total 0
lrwxrwxrwx 1 root root 10 Jun  1 11:32 2552539a-3629-4d2e-b31c-84c5661ca2ee -> ../../sda3
lrwxrwxrwx 1 root root 10 Jun  1 11:32 68de703e-efa0-4ea7-b49a-5456b4258e80 -> ../../sda2
lrwxrwxrwx 1 root root 10 Jun  1 11:32 9d3e0112-834d-42e7-9648-ace061722ed7 -> ../../sda1

The image is in /boot:

total 19M
-rw-r--r-- 1 root root 5.3M Apr 26 10:22 bzImage-2.6.38.2-xxxx-grs-ipv6-32
drwxr-xr-x 2 root root 4.0K Jun  3 21:52 grub
-rw-r--r-- 1 root root 7.3M Jun  3 21:45 kernel26-lts-fallback.img
-rw-r--r-- 1 root root 1.7M Jun  3 21:45 kernel26-lts.img
drwx------ 2 root root 4.0K Dec 17  2009 lost+found
-rw-r--r-- 1 root root 1.6M Apr 26 10:22 System.map-2.6.38.2-xxxx-grs-ipv6-32
-rw-r--r-- 1 root root 1.1M May 24 12:19 System.map26-lts
-rw-r--r-- 1 root root 1.8M May 24 12:19 vmlinuz26-lts

Can someone confirm I should be OK with this setup?

Last edited by Rolinh (2011-06-03 19:56:29)

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Well, it did not reboot. Thanks to the rescue mode of my hosting provider, I could rollback my changes and boot on the usual kernel after having lost access to my server for about 1 hour.
Does anyone have any idea why? I do not see where I did wrong.

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

No one?

twl

Member

Registered: 2011-05-30

Posts: 20

Re: LTS Kernel + remote server

Im curious myself, Im no expert in this area but your settings looked like they would work

stqn

Member

Registered: 2010-03-19

Posts: 1,191

Website

Re: LTS Kernel + remote server

Your menu.lst looks ok to me too; maybe the hosting provider includes some important driver in their bzImage that you don't have in the default LTS kernel...

Why do you want to use a different kernel anyway?

I'm wondering what happens when you run pacman -Syu and there is a new kernel though... Does it use their own mirror to install their own strange kernel?

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Why do you want to use a different kernel anyway?

Well, for me it seemed obvious: a server needs to be up and running as much as possible. Having the LTS kernel means less reboot.

I'm wondering what happens when you run pacman -Syu and there is a new kernel though... Does it use their own mirror to install their own strange kernel?

Actually, I'm curious too. I read this and this but I am not sure if it means I cannot use Archlinux's own kernel. What do you think about?

stqn

Member

Registered: 2010-03-19

Posts: 1,191

Website

Re: LTS Kernel + remote server

Yeah, it looks like they don't expect you to use anything else than their pre-built kernels.

Edit: I guess the kernel26 package isn't installed, or doesn't need to be installed, then...

Last edited by stqn (2011-06-07 17:20:04)

Rolinh

Member

From: Switzerland

Registered: 2011-05-07

Posts: 144

Website

Re: LTS Kernel + remote server

Hmmm... So I need to dig further about their kernels.

You're exactly right: kernel26 is not even installed...