Karl Larsen wrote: All people are asking is to stick to fedora-related topics here, and at least try to be be accurate in your descriptions so some cause/effect logic can be attempted. Most people search this list for answers to questions before asking them again. Just imagine how hard that will be now for the new user looking for the one simple command line it takes to use dd. Also, it helps both people reading the discussion currently and in the archives to reply to existing threads when continuing that topic and to start new threads with different subjects when the topic changes. You don't need to stop posting to stop making it difficult for others. -- Les Mikesell lesmikesell(a)gmail.com

Karl Larsen wrote: There is nothing really fedora-specific about using dd to copy things. It has worked the same way in all unix-like systems for decades. The device names and what you have to fix in grub.conf and fstab are somewhat linux specific if you copy partitions instead of the whole disk. But, no one objects to simple question/solution threads on how to do something in fedora even if it is the same in many other distributions. I think this: http://fedoraproject.org/wiki/Communicate/MailingListGuidelines has already been pointed out. In particular, try the search tips before posting to see if your question has already been asked and has a known answer. Then, when you are posting something new, try to do it in a way that the next person who needs the same answer will be able to find it quickly with an archive search. Remember, everything you are posting will be archived away (virtually) forever. -- Les Mikesell lesmikesell(a)gamil.com

On Sun, 2007-09-02 at 22:50 -0500, Arthur Pemberton wrote: I thought Les did a mighty fine job of addressing the issue. It was clear, concise, informative, suitable for archive and non-judgmental. The last time I ever used dd was to create boot-floppies back in the day from a disk image. Otherwise, cp does the job of copying files, not dd. As Les pointed out it copies blocks as opposed to files. The entire episode was kinda like watching someone using a pipe wrench to put up a picture frame on the wall. The group just wanted the OP to grab a hammer. Live long and prosper. Ric -- ================================================ My father, Victor Moore (Vic) used to say: "There are two Great Sins in the world... ..the Sin of Ignorance, and the Sin of Stupidity. Only the former may be overcome." R.I.P. Dad. Linux user# 44256 Sign up at: http://counter.li.org/ http://www.sourceforge.net/projects/oar http://www.wayward4now.net <---down4now too ================================================

On Sun, 2007-09-02 at 23:11 -0500, Arthur Pemberton wrote: Why not here where, this longish discussion has gone on? Heck, I learned something out of Les's comment. It doesn't get anymore Fedora centric than here! :) Ric -- ================================================ My father, Victor Moore (Vic) used to say: "There are two Great Sins in the world... ..the Sin of Ignorance, and the Sin of Stupidity. Only the former may be overcome." R.I.P. Dad. Linux user# 44256 Sign up at: http://counter.li.org/ http://www.sourceforge.net/projects/oar http://www.wayward4now.net <---down4now too ================================================

On Sun, 2007-09-02 at 18:11 +0100, Ian Malone wrote: Man pages are not useful to someone without considerable background. As you gain experience (and the knowledge that others are willing to share with you), they become more helpful. Most man pages are only basically useful, which is what spurred the development of Info as I understand it, and of course I often see even the most knowledgeable of our compatriots here refer to wiki pages, wiki books, Fedora documentation, and other sources, and some of these sources conflict, but if you have some other knowledge and experience, you can sort the wheat from the chaff (most of the time anyway), and get what you need. For someone like Karl, who is using the machine for a task, and only learning what he needs to get by, these sources are often less than useful. Trust me, I remember learning on my own decades ago. That is why I try to be clear, concise and helpful. If you have "the gift" of technology comprehension, you are lucky. Most folks are not. I hope you can find the help you need in those resources, but I also hope that I and others on this list will be helpful to you as well. Regards, Les H

Craig White wrote: I will wear it and just read info dd for about the 4th time in 5 days. The first time I read it I was not aware that dd sends Everything including the file system. The info dd does not say this. I tried to copy this f7 which is about 8 Gbytes to another partition that was 10 Gbytes. The transfer failed because the 8 Gbyte f7 was from a 40 Gbyte partition :-) If you read everything in info dd you will not see this listed. Google of dd gives you a lot of information but I have not seen any example of a 40 Gbyte copy. So it may be time to get the author of the dd info to add something about large copies and the use of the Rescue CD. -- Karl F. Larsen, AKA K5DI Linux User #450462 http://counter.li.org.

On Sun, 2007-09-02 at 21:23 +0100, Ian Malone wrote: Hi, Ian, This is one of the aspects of computers that someone with experience understands and someone else may not. Karl, The disk contains not only the partition table, files and data, but also many blocks of data that contain information about how the files are stored, the superblocks. These are linked. If one changes, they all change. The dd utility looks at the disk and finds its size, then copys that to the output file system. This will include the superblocks and everything else that is tied to the disk structure that is visible to the outside world. There is also data on the disk that is not visible to the outside world that is used by the interface, but dd won't see that, and won't copy it (doesn't have access). The disk structure then is spread out over the full size of the disk. Moreover, when you edit or update a file, it is not generally done "in place", but rather a new file is created, then the old one is erased. This means a disk can have voids in its cylinders (not a bad thing, because this process prevents excessive writes to the same areas of the disk to some extent, thus prolonging the life of the disk slightly). As a result, the "clone tools" such as dd and a few others that I used to use, will copy the disk literally. As long as the disks are the same basic physical structure this works. But if the size is different, the cylinder size is different, or the sector size is different then it will not work well, although it may complete successfully. If the cylinders have more sectors, some will be left blank, and due to the design of the superblocks, not accessible after the clone is complete. If the cylinders have fewer sectors (not a likely scenario today, but used to happen), then the clone would overwrite on successive sectors past the physical number unless it detected the error. If the disk is faster or slower in rotation, it can also cause problems, as can relative bandwidth of the heads, but generally the controller will attempt to set this correctly. Thus dd has evolved over the years to detect most of the possible errors and prompt you to not continue. However, since dd is also a catastrophe tool, it will proceed if told to do so, so that someone in a bad situation may be able to clone the disk to a larger disk and hopefully recover their data. It has been pointed out in this thread that this is also sometimes the process used by computer forensics folks to clone the disk to avoid tampering with its contents, and then work only on the clone. This is one of those tools that can do a lot of damage if used unwisely, and so as many folks here told you, using the same identical hardware is critical to ensuring success in the most basic manner. Another issue that arises in dynamic systems that are interrupt and demand driven like all modern multithreaded systems is the possibility of file modifications. This would result in a "snap shot" of a file system in transition, which could possibly cause catastrophic failure should the cloned system be used to boot. One of the responders I felt gave a really good example of a book being written as it was copied. And, no, the man and info pages do not detail exactly what dd does or the potential interactions. However I do believe that they say to not perform the operation on mounted systems, and that the systems should be the same or at least the same size. In short, man pages are abbreviated to "just the facts, Ma'am" as Joe Friday used to say. Therefore using commands just based upon man one should always follow very carefully every argument, every precaution, and not do anything else. Otherwise, you need more information. This is true of most every *nix command, as most have evolved over the years to much greater capability than was originally envisioned. The original mantra was for each command to do one thing, but do it well and be capable of chaining to other command through pipes or I/O redirection to accomplish complex tasks. However as systems have grown, our ability to segment the complex tasks is being overwhelmed, so commands get more and more capabilities, necessitating manuals for some of the commands, and more understanding of the OS and system functions and processes. The command dd falls into this category, but so do most other commands. I do not believe that man should be your only source, but I do agree that one should read and follow the man recommendations religiously. This applies to old hands as well as new. I have seen "we've always done it this way" go too far wrong in many cases. Be careful. And by the way, Karl, you did the right thing. Write down what you did. Get it clarified, and improve it, whether for yourself or for wider dissemination. That is the true spirit of open source. The gentleman here said make a contribution to man. I believe you have made a contribution, perhaps not to man, but to several folks out there who did not understand what was happening or why. I hope I have helped here. But if not... at least I tried. Good luck to you both. Regards, Les H

Ian Malone wrote: Unless you use the -vw option. :-) -- Everything is controlled by a small evil group to which, unfortunately, no one we know belongs.