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Hi,<br>
<br>
When I make DVDs of Centos and any others for that matter, I take
the following steps:<br>
<br>
1. Find an official torrent if possible. (Centos has torrents for
the DVD. Unfortunately no Jigdo so far as I know.)<br>
<br>
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.<br>
<br>
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.<br>
<br>
<br>
2. Once the file is downloaded do a binary checksum using the
official checksums found on the vendors homepage or mirror you
downloaded from. <br>
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)<br>
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.<br>
<br>
<br>
3. Burning the DVD. This step is the trickiest part to get right.<br>
<br>
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.<br>
<br>
3.2. Use the following wodim command:<br>
<br>
"/usr/bin/wodim dev=/dev/sr0 driveropts=burnfree fs=14M speed=4 -dao
${ISO_FILENAME}" where /dev/sr0 is your DVD device and
${ISO_FILENAME} is your iso you are trying to burn.<br>
<br>
to burn the DVD at the slowest possible speed your DVD burner will
go for. Use DISK AT ONCE (dao) to write the whole file in one go.
Wodim will close the disk session after burning. I know nothing
about using windows tools to burn DVDs as I do this on Linux. <br>
<br>
<br>
4. Check the media against the official checksum you used in step
2. Here are my steps for doing this. Again this has to be done
right. Sometimes you will get different results if you try to
simply call sha512sum -b /dev/sr0 where /dev/sr0 is your DVD drive.<br>
<br>
4.1. Use the isoinfo tool to retreive the blocksize and blockcount
of the DVD you are checking. (/usr/bin/isoinfo -d -i /dev/sr0 where
/dev/sr0 is your DVD device.)<br>
<br>
4.2. Use dd to read the disk using the correct blocksize and
blockcount settings and pipe through the checksum tool. <br>
<br>
IE: "/bin/dd if=/dev/sr0 bs=${blocksize} count=${blockcount}
conv=notrunc,noerror status=noxfer | sha512sum -b" where
${blocksize} and ${blockcount} are the numbers you retrieved from
using isoinfo.<br>
<br>
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.<br>
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.<br>
<br>
<br>
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.<br>
I do not know of a better way, without actually installing the OS,
of verifying that the media is good.<br>
I have all this scripted so complete all these steps every time I
ship a DVD to any customer who orders one. <br>
<br>
Best regards<br>
David Latham<br>
<br>
<a class="moz-txt-link-freetext" href="http://www.thelinuxcdstore.com">http://www.thelinuxcdstore.com</a><br>
<br>
<br>
<span style="white-space: pre;">> Message: 1<br>
> Date: Mon, 03 Jan 2011 13:37:17 -0500<br>
> From: "Lisandro Grullon" <a class="moz-txt-link-rfc2396E" href="mailto:lgrullon@CityTech.Cuny.Edu"><lgrullon@CityTech.Cuny.Edu></a><br>
> Subject: Re: [CentOS] Centos 5.5 - Kernel Panic while
booting.<br>
> To: <a class="moz-txt-link-rfc2396E" href="mailto:amyagi@gmail.com"><amyagi@gmail.com></a><br>
> Cc: <a class="moz-txt-link-abbreviated" href="mailto:centos@centos.org">centos@centos.org</a><br>
> Message-ID:
<a class="moz-txt-link-rfc2396E" href="mailto:4D21D10D020000890000F53B@email2.citytech.cuny.edu"><4D21D10D020000890000F53B@email2.citytech.cuny.edu></a><br>
> Content-Type: text/plain; charset="us-ascii"<br>
><br>
> 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!<br>
><br>
>>>> Akemi Yagi 12/17/10 8:13 PM >>><br>
> On Fri, Dec 17, 2010 at 5:11 PM, Lisandro Grullon<br>
> wrote:<br>
>> Akemi,<br>
>> I went through the different mirrors and was unable to
locate the ISO as it<br>
>> is stated as deprecated or unsupported, is there any
plans to fix this issue<br>
>> in 5.6 or rather 6.x release. It appears that the latest
build from Centos<br>
>> was built back in may, lots of bugs have emerge since
them including this<br>
>> one relating to a kernel panic. Please advise in the
location of 5.4, i am<br>
>> willing to try it.<br>
><br>
> It's here:<br>
><br>
> <a class="moz-txt-link-freetext" href="http://vault.centos.org/5.4/">http://vault.centos.org/5.4/</a><br>
><br>
> Akemi<br>
><br>
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