bootable flash for centos 7

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kbr
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Re: bootable flash for centos 7

Post by kbr » 2019/05/22 14:30:35

Well for me personally if it solves my problem then it's the right tool for the job. LibreOffice is a bad example because it consistently mangles both plaintext and .docx files. But again, nobody's saying you can't use win32 disk imager, if for some reason you find it more suitable.

Edit: Without specific examples, it seems primarily opinion-based to state one is better than the other. Do you have any specific examples of a case of a particular CentOS ISO that worked on win32 disk imager, but didn't work using Rufus, when you tried to install it on a particular model of server/desktop/laptop?

owl102
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Re: bootable flash for centos 7

Post by owl102 » 2019/05/22 18:48:45

kbr wrote:
2019/05/22 14:30:35
Do you have any specific examples of a case of a particular CentOS ISO that worked on win32 disk imager, but didn't work using Rufus, when you tried to install it on a particular model of server/desktop/laptop?
Yes.

Just make a quick search in this forum (and in the Fedora forum and in the Debian forum and...) and you'll find such instances. Furthermore I often join meetings of my local Linux group, and we often had to fix Rufus problems, too. (Usually Linux was installed in BIOS/CSM mode since Rufus broke UEFI support of the ISO, and therefore dual boot with MS-Windows did not work via Grub.)
Last edited by owl102 on 2019/05/22 21:04:06, edited 1 time in total.
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TrevorH
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Re: bootable flash for centos 7

Post by TrevorH » 2019/05/22 19:32:22

For a Windows machine I would recommend using rawrite2 if dd is not available. We have a link to a known working copy in our wiki USB install page. Information on USB key based installs can be found at http://wiki.centos.org/HowTos/InstallFromUSBkey. It does one thing - it copies disk images to disk. It doesn't modify them and it's been working since 3.5" floppies were a thing.
CentOS 6 died in November 2020 - migrate to a new version!
Info for USB installs on http://wiki.centos.org/HowTos/InstallFromUSBkey
CentOS 5 is dead, do not use it.
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kbr
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Re: bootable flash for centos 7

Post by kbr » 2019/05/22 19:58:43

owl102 wrote:
2019/05/22 18:48:45
Yes.

Just make a quick search in this forum (and in the Fedora forum and in the Debian forum and...) and you'll find such instances. Furthermore I often join meetings of my local Linux group, and we often had to fix Rufus problems, too. (Usually Linux was installed in BIOS/CSM mode since Rufus broke UEFI support of the ISO, and therefore dual boot with MS-Windows did not work.)
Ok, so to confirm, you have the examples, but you are not willing to link them or be in any way specific other than listing a number of distros. However, you are willing to take the time to keep responding to this post.

I'd say if there is an actual problem with rufus, be specific, state which computers/setups it failed for. If we compile this information I can even make a bug report on the rufus repository, as it is currently being actively developed. Maybe the problem would even get fixed if you were interested in providing specific failure cases (i.e. an instance where running rufus in the correct mode creates a non-working ISO).

Disclaimer: I am not a developer for rufus or in any way affiliated with their project, but I am opposed to people bashing open-source projects in a non-constructive way. Furthermore it is completely inaccurate to call a project *obsolete* when it:
  • Successfully creates an ISO for CentOS 7
  • Supports a large number of Linux distros
  • Is being actively developed (latest commit 22 hours ago)

owl102
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Re: bootable flash for centos 7

Post by owl102 » 2019/05/22 21:42:30

kbr wrote:
2019/05/22 19:58:43
Ok, so to confirm, you have the examples, but you are not willing to link them or be in any way specific other than listing a number of distros. However, you are willing to take the time to keep responding to this post.
And you are willing to take the time to keep responding, too, but are not willing to search for "Rufus" in Linux forums.

However, I will collect some threads on the week-end and/or will do own tests. (Sorry, I don't have time for this during the week-days.)

In the meantime I would like to quote from https://wiki.centos.org/HowTos/InstallFromUSBkey:
https://wiki.centos.org/HowTos/InstallFromUSBkey wrote: Rufus (may depend on options selected, there have been reports of failure with rufus too)
especially the "there have been reports of failure" part of it.
but I am opposed to people bashing open-source projects in a non-constructive way.
IMHO you are missing the point here. This has nothing to do with bashing. Rufus was a very useful tool in the past, and it was necessary to use tools like Rufus or Unetbootin to get booting USB sticks. I have used them myself with success, and I was very glad that these tools exist. But since all Linux ISO are hybrid ISO now the main functionality of these tools (means: writing a modified version of the ISO to the USB stick) is simply not needed anymore, instead, it could break things.

For this reason I call tools like Rufus obsolete, at least when it comes to writing Linux ISO to a USB stick. Again, this has nothing to do with bashing, and this does not make them bad tools. One of the main reasons for their existence has gone, it's simply that. You only need such tool for non-hybrid ISOs, i.e. very old versions of CentOS, Fedora, Debian etc.

Furthermore I tend to differ about "using" and "recommending". There are a lot of tools I use and like, but I would not recommend them to (new) users. For me Rufus fits into this category, too, since the easiest and safest way to get a 1:1 copy of the ISO to the USB stick is by using a tool which just does this. So even if I would use Rufus myself, I would not recommend it, but instead recommend tools like Win32 Disk Imager or the Fedora Media Writer.

Writing a bug report seems useless to me since Rufus modifies the ISO on purpose. That's its job and that was the reason why Rufus was written in the first place. Fixing this would mean stripping Rufus down to a simple 1:1 copy application, or at least hide all options which do modify the ISO behind a "expert mode" button or menu.
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owl102
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Re: bootable flash for centos 7

Post by owl102 » 2019/05/27 12:04:16

I gave an intern the job to put a CentOS 7 Minimal ISO on two USB sticks, one using Win32 Disk Imager and the other one using Rufus with default settings, i.e. loading the ISO and putting it onto the stick without changing any parameters in Rufus. Afterwards I have read back the ISO from the USB drives and have checked the sha256. The result:

Code: Select all

# dd if=/dev/sdb of=CentOS-7-x86_64-Minimal-1810-Rufus.iso bs=1M count=918
...
# dd if=/dev/sdb of=CentOS-7-x86_64-Minimal-1810-W32DI.iso bs=1M count=918
...
# sha256sum CentOS-7-x86_64-Minimal-1810*
38d5d51d9d100fd73df031ffd6bd8b1297ce24660dc8c13a3b8b4534a4bd291c  CentOS-7-x86_64-Minimal-1810.iso
6768b216d8745f0398e8d1de54db961500a38bf3bf10ee74beac10d461ecdd21  CentOS-7-x86_64-Minimal-1810-Rufus.iso
38d5d51d9d100fd73df031ffd6bd8b1297ce24660dc8c13a3b8b4534a4bd291c  CentOS-7-x86_64-Minimal-1810-W32DI.iso
# more sha256sum.txt 
..
38d5d51d9d100fd73df031ffd6bd8b1297ce24660dc8c13a3b8b4534a4bd291c  CentOS-7-x86_64-Minimal-1810.iso
...
So Rufus has altered the contents of the ISO before writing it to the USB stick. Furthermore the media check will be skipped (with an error message? It happens to fast too for reading the message) when booting the stick written by Rufus. I haven't check the installation from USB since the altered ISO and the missing media check is sufficient to not recommend Rufus, at least for me.
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Akeo
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Joined: 2021/04/05 15:55:46

Re: bootable flash for centos 7

Post by Akeo » 2021/04/05 16:26:34

Rufus developer here.

This claim is wrong.

If you do write the ISO in DD mode, you will find that Rufus does not alter the content of the ISO.

This is a test I just ran on CentOS-8.3.2011-x86_64-minimal.iso after writing it with Rufus in DD mode:

Code: Select all

root@nano:/mnt# dd if=/dev/sda of=centos.iso bs=1M count=1780 status=progress
1862270976 bytes (1.9 GB, 1.7 GiB) copied, 78 s, 23.9 MB/s
1780+0 records in
1780+0 records out
1866465280 bytes (1.9 GB, 1.7 GiB) copied, 78.5396 s, 23.8 MB/s
root@nano:/mnt# sha256sum centos.iso
191daa949a021733bbc19ae42dd1280b30d4ded7e316733461a2efb4463fbfed  centos.iso
root@nano:/mnt# sha256sum CentOS-8.3.2011-x86_64-minimal.iso
191daa949a021733bbc19ae42dd1280b30d4ded7e316733461a2efb4463fbfed  CentOS-8.3.2011-x86_64-minimal.iso
Of course, if you write the ISO in ISO mode rather than DD mode, a.k.a. file copy mode, the SHA256 won't match since the underlying partitions and file system structure will be different (for one thing FAT32 will be used instead of ISO9660), in which case you should compare the SHA/MD5 of the individual files.

If you are assuming that ISO mode should be the same as DD mode, then I have to ask you, why exactly do you believe that these two options are there in the first place? If the end result of ISO mode is meant to be the exact same thing as DD mode, why on earth would Rufus ask users to choose between the two?

Oh, and if you believe that DD mode is a panacea, and should be the only option offered to users (whereas distros like Arch, Debian and Ubuntu do understand that users, especially ones running UEFI platforms, should be offered the choice of installing their OS by simply extracting the ISO content to a FAT32 partition, as it may be more convenient), you may want to read this.

owl102
Posts: 394
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Re: bootable flash for centos 7

Post by owl102 » 2021/04/05 17:07:09

Akeo wrote:
2021/04/05 16:26:34
If you do write the ISO in DD mode, you will find that Rufus does not alter the content of the ISO.
Yes, but the DD mode is not the default mode in Rufus. And it is much easier to tell users to simply not use Rufus than explaining to them what mode and what settings they need to choose to get a proper result.

For CentOS ISOs Rufus is just a dd with additional options which causes the result to be incorrect, at least from my point of view. So why use Rufus in the first place? Why not simply use dd or another tool which only makes 1:1 copies instead? (Same with Fedora, Debian, ... and nearly all Linux ISOs.)

(Rufus may be a great tool for power users but for non-power users it's IMHO just too error prone.)
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Akeo
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Re: bootable flash for centos 7

Post by Akeo » 2021/04/05 17:43:12

I very much like that your reasoning for not having to explain technical details to end users (such as why Windows will not display the USB content because it doesn't support the file system commonly used to produce a ISOHybrid) is the precise reason why Rufus recommends ISO mode.

If you read the link I pointed you to, you will see, through literally dozen of examples, all referenced on that link, that DD mode is actually very confusing for Windows users, and especially first time Linux users, who will think that their media was not created properly and decide not install Linux as a result.

But obviously, this aspect of things seems to be missed on DD über alles proponents, who appear to be completely oblivious to the plight of first time Linux users coming from Windows, and seem to dismiss the idea that the situation between ISO and DD mode is a bit more nuanced than "You should only ever use DD", despite being provided with verifiable evidence that DD for ISOHybrid is not always a panacea (and I could also point you to cases where a media created in ISO mode boots fine, whereas the same media created in DD mode doesn't).

And this had nothing to do with Rufus, or other utility being used. Just that DD doesn't always help users.

So, to answer your "Why not simply use dd or another tool which only makes 1:1 copies instead?", I will refer you once again to this, that explains why.

Akeo
Posts: 10
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Re: bootable flash for centos 7

Post by Akeo » 2021/04/05 19:27:08

EDIT: The previous post, to which this one is a reply, was deleted, so it may not make sense without the full context.

I beg to differ. A lot of the conversations I am seeing have the moderators asking OP to try with a different utility, and OP reporting that it did not fix their issues. And, I can also very easily point you to this where user with a problem got through the usual "Oh you created your media using Rufus ISO mode? Don't ever do that, instead recreate in DD mode instead" and where they ended up with something that did not boot at all.

So your "typical" differs greatly from my "typical".

As to your "I never get complaints about this", it seems to indicate to me that you're not looking very hard outside your immediate surroundings, as other user forums are replete with these kind of issues from Windows users, and I can't vouch for why the people who do report that DD mode is confusing for them do not report it directly to you. That, however, and I hope you can appreciate that, doesn't mean that those issues aren't real.

Now, my current understanding is that, as opposed to what Arch, Debian and Ubuntu are doing, which is to ensure that one can just pick an ISO, extract the content to a FAT32 file system (possibly after editing the config options to make the installation disk's label compatible with the FAT32 one), and use that media for booting a UEFI system (which can be more convenient than using DD mode), CentOS 8.3 has taken the path to remove that option, whereas it was still achievable in 8.2.

Obviously, this means that this will create problems with ISO mode, which is not a big deal, as we just can do what with the couple other distros that have chosen to go down that road and force DD mode always. But I sure wouldn't mind if CentOS maintainers would look around at what other distro maintainers have chosen to do, and possibly try to understand why, "surprisingly", the most popular distros are still not jumping onto the "DD only" bandwagon (which, again, has to do with trying to provide the users with choice and ultimately improving their experience).

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