[CentOS] Centos 5.5 - Kernel Panic while booting.

David Latham david at thelinuxcdstore.com
Wed Jan 5 06:50:17 EST 2011


Hi,

When I make DVDs of Centos and any others for that matter, I take the
following steps:

1. Find an official torrent if possible.  (Centos has torrents for the
DVD.  Unfortunately no Jigdo so far as I know.)

1.1 Torrents come with checksums and the torrent app I use will check
the downloaded file against the checksums. Otherwise find a stable
mirror close to where you are for better speed.

1.2 If you cant get a torrent find out if the distro vendors offer any
other options.  IE: Jigdo, zsync etc. etc.  I usually try for one of
these before going for a strait FTP download.  FTP downloads often fail
and are not always recoverable in the event of an interruption.  Jigdo
is my favourite as each and every package and file is downloaded and
verified and then the DVD image (.iso) made up from all the packages. 
It is basically a self checking system and has proven to be very reliable.


2. Once the file is downloaded do a binary checksum using the official
checksums found on the vendors homepage or mirror you downloaded from. 
Information on how to call sha512sum or any checksum tool to make it do
a binary level checksum can be found in the man pages. (sha512sum -b
filename.iso)
I always go for the largest checksum algorithm provided.  IE: SHA512SUM
if available otherwise SHA256SUM, SHA1SUM or as a last resort MD5SUM. 
If this passes proceed to step 3.


3. Burning the DVD.  This step is the trickiest part to get right.

3.1. Find **reliable** media.  Always choose DVD-R.  Go with a named
brand.  I usually go for spindles of 50 or less.  I have found that the
100 unit spindles get a bit heavy on the ones at the bottom and I am
unsure of the effect shipping and handling has on them.

3.2. Use the following wodim command:

"/usr/bin/wodim dev=/dev/sr0 driveropts=burnfree fs=14M speed=4 -dao
${ISO_FILENAME}" where /dev/sr0 is your DVD device and ${ISO_FILENAME}
is your iso you are trying to burn.

to burn the DVD at the slowest possible speed your DVD burner will go
for.  Use DISK AT ONCE (dao) to write the whole file in one go.  Wodim
will close the disk session after burning.  I know nothing about using
windows tools to burn DVDs as I do this on Linux.


4. Check the media against the official checksum you used in step 2. 
Here are my steps for doing this.  Again this has to be done right. 
Sometimes you will get different results if you try to simply call
sha512sum -b /dev/sr0 where /dev/sr0 is your DVD drive.

4.1. Use the isoinfo tool to retreive the blocksize and blockcount of
the DVD you are checking. (/usr/bin/isoinfo -d -i /dev/sr0 where
/dev/sr0 is your DVD device.)

4.2. Use dd to read the disk using the correct blocksize and blockcount
settings and pipe through the checksum tool.

IE: "/bin/dd if=/dev/sr0 bs=${blocksize} count=${blockcount}
conv=notrunc,noerror status=noxfer | sha512sum -b" where ${blocksize}
and ${blockcount} are the numbers you retrieved from using isoinfo.

conv=notrunc,noerror come from another post I found once.  So far so
good...  The dd man page explains that notrunc means do not truncate the
output file and noerror means continue after read errors.
status=noxfer is just to keep the whole thing a little quieter by not
displaying transfer statistics.  You can play with these settings if you
like.  They have done me fine for over 400 burns since I started doing
this over 2 years ago.


This will produce a checksum you can visually compare with the official
checksum you retrieved from the mirrors to confirm if your disk is good.
I do not know of a better way, without actually installing the OS, of
verifying that the media is good.
I have all this scripted so complete all these steps every time I ship a
DVD to any customer who orders one.

Best regards
David Latham

http://www.thelinuxcdstore.com


> Message: 1
> Date: Mon, 03 Jan 2011 13:37:17 -0500
> From: "Lisandro Grullon" <lgrullon at CityTech.Cuny.Edu>
> Subject: Re: [CentOS] Centos 5.5 - Kernel Panic while booting.
> To: <amyagi at gmail.com>
> Cc: centos at centos.org
> Message-ID: <4D21D10D020000890000F53B at email2.citytech.cuny.edu>
> Content-Type: text/plain; charset="us-ascii"
>
> This was very helpful Akemi...I was loading centos in two other
identical servers today and was having such a hard time loading it from
DVD, DVD appears to be crashing, I even re-downloaded the image 3 times
from three different mirrors and burn them with different applications
(Nero, Roxio, and poweriso), worse case scenario it must be something
with the Memorex DVD Media. Anyway, after two hours of trying I decided
to do a network install and everything went flawless. Good to have many
options, Centos rocks!
>
>>>> Akemi Yagi 12/17/10 8:13 PM >>>
> On Fri, Dec 17, 2010 at 5:11 PM, Lisandro Grullon
> wrote:
>> Akemi,
>> I went through the different mirrors and was unable to locate the ISO
as it
>> is stated as deprecated or unsupported, is there any plans to fix this
issue
>> in 5.6 or rather 6.x release. It appears that the latest build from Centos
>> was built back in may, lots of bugs have emerge since them including this
>> one relating to a kernel panic. Please advise in the location of 5.4, i am
>> willing to try it.
>
> It's here:
>
> http://vault.centos.org/5.4/
>
> Akemi
>
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