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| ubuntourist | tboimah, hi. Sorry I'm late.e | 14:18 |
|---|---|---|
| tboimah | Good morning Mr Cole | 14:18 |
| mulbah | Good morning | 14:18 |
| ubuntourist | hi mulbah sorry i'm late. | 14:18 |
| mulbah | Okay no problem | 14:18 |
| ubuntourist | I'm also sorry I haven't prepared anything. But I was planning to talk a bit about what "boot" means. | 14:19 |
| ubuntourist | First, do either of you have progress to report or questions to ask? | 14:20 |
| tboimah | yes | 14:21 |
| ubuntourist | tboimah, go ahead | 14:21 |
| tboimah | I have install the virtual machine manager and i am now trying to install some os on it | 14:21 |
| tboimah | and i am almost finish with the page that talk about the server | 14:23 |
| tboimah | ACTION done | 14:23 |
| ubuntourist | tboimah, good to know. | 14:23 |
| ubuntourist | mulbah, anything from you? Questions? Progress? | 14:24 |
| mulbah | Yeah progress | 14:24 |
| mulbah | I have been reading the book and writing down some questions and answering them | 14:25 |
| mulbah | the same tboimah said | 14:25 |
| ubuntourist | (I didn't get around to looking at specifics of BIOS verses UEIF.) | 14:25 |
| ubuntourist | mulbah, good to hear. | 14:26 |
| mulbah | that i will soon finish with the page that talk about server | 14:26 |
| ubuntourist | I wanted to talk a little about "booting" and it relates to BIOS / UEFI stuff. | 14:28 |
| ubuntourist | Computer chips are small and fast, but unfortunately expensive to produce. | 14:28 |
| ubuntourist | And, early chips needed electrical power to "remember" anything. If you turned the machine off, | 14:29 |
| ubuntourist | or cut the power, anything data on a computer chip would become random garbage. | 14:30 |
| ubuntourist | In contrast, magnetic storage --- magnetic tape and magnetic disks -- were inexpensive, and didn't | 14:31 |
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| ubuntourist | need power to "remember" what was stored on them. But they were big, slow, and inefficient. | 14:32 |
| ubuntourist | So, manufactuers needed to compromise: How do you balance the need for speed with the need for permanence? | 14:33 |
| ubuntourist | You can make chips with data burned into them that can never be changed. So, you could have an expensive chip with an | 14:34 |
| ubuntourist | application burned in, and that application would locate data on a tape or disk, read it into memory chips, and then start | 14:35 |
| ubuntourist | using what was loaded into memory. | 14:35 |
| ubuntourist | In Python, you have both used the "import" statement, right? | 14:36 |
| mulbah | Yeah | 14:37 |
| mulbah | to import module | 14:37 |
| ubuntourist | OK. So that is -- very roughly -- a similar idea: Imagine that your program was burned into a chip, and could never be changed. | 14:38 |
| ubuntourist | BUT, the module that you were importing was NOT burned into a chip, and you could edit it and improve it. | 14:38 |
| ubuntourist | The word "boot" comes from an old story or joke. Hold a sec... | 14:40 |
| ubuntourist | The story or joke refers to men who were trying to climb something impossble to climb. But the joke is, | 14:42 |
| ubuntourist | "Well, if they could reach down to their boots and pull the bootstraps hard, then they could 'levitate'." | 14:43 |
| ubuntourist | It's a silly, nonsense idea called "pulling yourself up by your own bootstraps". | 14:44 |
| ubuntourist | Early in the history of computers, someone came up with the expression "bootstrap loader" to describe the process of | 14:45 |
| ubuntourist | starting an operating system: A tiny program, burned into a small chip would read a larger program from tape or disk -- | 14:45 |
| ubuntourist | like importing a module -- and then use that module to read an even larger module from the tape or disk, and then use THAT module | 14:46 |
| ubuntourist | to read bigger and more modules iinto memory. The computer was "pulling itself up by its own bootstraps" or "booting". | 14:47 |
| ubuntourist | In the present, disks are becoming faster and smaller, and many aren't really even disks any longer, although we still use the word. | 14:48 |
| ubuntourist | (Early disks were really much more like phonograph records: They spun and had a movable arm that woul position itself over the magnetic impulses | 14:49 |
| ubuntourist | in a way that is similar to a phonograh needle positioning itself over a grove etched in vinyl.) | 14:50 |
| ubuntourist | Even though the difference between traditional hardware chips and "hard disks" is shrinking, the process of booting is still | 14:51 |
| ubuntourist | similar to ancient times. | 14:51 |
| ubuntourist | First, the computer's burned in program performs a quick self-check to see if memory and other components are working as they should. | 14:52 |
| ubuntourist | This is referred to as the POST -- Power On Self Test | 14:53 |
| ubuntourist | Then, it starts the boot process of reading a program to tell it what to do next. | 14:53 |
| ubuntourist | IMPORTANT: At this stage, the computer does not understand what a file is, or what a directory is. | 14:54 |
| ubuntourist | At this point in the boot process, it is doing something purely mechanical. Think of gears in a car or a bicycle or some other mechanical | 14:55 |
| ubuntourist | device. | 14:56 |
| ubuntourist | FIrst BIOS then a little bit about UEFI. | 14:56 |
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| ubuntourist | Hold a sec. I want to find a good picture to link to... | 14:57 |
| ubuntourist | https://en.wikipedia.org/wiki/Cylinder-head-sector | 14:58 |
| ubuntourist | Cylinder, head, and sector. Sometime referred to as cylinder, sector and track. | 14:59 |
| ubuntourist | In your studies -- both mathematics, and world geography, you've probably learned about three dimensional | 15:00 |
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| ubuntourist | coordinate systems: X, Y, and Z in mathematics, latitude, longitude, and altitude in world geography. | 15:01 |
| ubuntourist | In computers, the three coordinates are cylinder, sector and track or cylinder, head and sector. | 15:01 |
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| ubuntourist | ACTION waits to see if tboimah and mulbah are on or off. Lots of quit / join / quit messages... | 15:03 |
| ubuntourist | tboimah, mulbah both still here? | 15:03 |
| tboimah | we are on | 15:03 |
| mulbah | we are on | 15:03 |
| ubuntourist | Ok. | 15:04 |
| ubuntourist | So. when BIOS finishes POST, it still doesn't know what a file is. But it does know very primitive instructions | 15:04 |
| ubuntourist | to position a mechanical arm over a specific cylinder, move inwards to a concentric ring, and read data from a "pie slice" | 15:05 |
| ubuntourist | on the hard disk. In other words, it finds a very specific location, based on three physical coordinates, and tries to read computer instructions | 15:06 |
| ubuntourist | from that. It is not looking for a file name, because it does not know what a file is. It only knows "Position a mechanical arm to X, Y and Z, and start reading | 15:07 |
| ubuntourist | magnetic pulses, and hope that those are statments that can be acted on. | 15:08 |
| ubuntourist | Understand so far? | 15:08 |
| tboimah | sure | 15:09 |
| ubuntourist | (Take a look at the Wikipedia article later for a better understanding.) | 15:09 |
| tboimah | getting the concert small small | 15:09 |
| mulbah | alright | 15:09 |
| ubuntourist | OK. So that brings us to what you're doing now: | 15:10 |
| ubuntourist | Oh. Before I go there: One more thing. We used to have just two concepts: | 15:11 |
| mulbah | What do you means Mr. Cole? | 15:11 |
| ubuntourist | Hardware -- which were either chips that were permanently programmed and unchangable, or were very changable but needed electical power all the time, | 15:12 |
| ubuntourist | Software -- which was stored on magnetic media. Slow to read and write, but able to stay the same without electical power. | 15:13 |
| ubuntourist | Now we have something between hardware and software -- firmware. | 15:13 |
| ubuntourist | Modern BIOS and UEFI are firmware. | 15:13 |
| ubuntourist | Saving firmware to chips ("flashing" the chips) is slow. But reading the fimware is "reasonably fast". | 15:15 |
| ubuntourist | So, firmware does not change often due to the slowness and difficulty of "flashing the chips". | 15:15 |
| ubuntourist | So. Your virtual machine is software that SIMULATES firmware. | 15:16 |
| ubuntourist | When you use virt manager to create a virtual computer, it sets up a file on your hard disk that has firmware that | 15:17 |
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| ubuntourist | reads from a virtual, unformatted hard disk. Again, IMPORTANT: The virtual computer firmware (BIOS / UEFI) does NOT know what | 15:18 |
| ubuntourist | a file is. It only knows X, Y, Z / latitude, longitude, altitude. | 15:18 |
| ubuntourist | When you are trying to load an operating system onto a real physical computer or a virtual computer, you must use a "file that is not really a file" | 15:19 |
| ubuntourist | It is a "disk imaage". A disk image is a "snapshot" of a hard disk that has a special cylinder, head and sector called the "boot sector". | 15:20 |
| ubuntourist | The boot sector has the module that tells the computer a lot of things. One of the important functions in the boot sector module | 15:21 |
| ubuntourist | tells the computer what a file and directory are. It is like drawing borders and naming countries on our latitude, longitude and altitude system. | 15:22 |
| ubuntourist | There is another special area of the disk called the "File Allocation Table" (FAT) that keeps a journal of which cylinders, sectors and tracks are currently | 15:23 |
| ubuntourist | in use (files containing data) and which are unused ("free disk space"). | 15:24 |
| ubuntourist | IMPORTANT: There are several DIFFERENT ways to do disk allocation -- the way that cylinders, sectors and tracks can be interpreted as files. | 15:25 |
| ubuntourist | These are called "filesystems". Linux understands several different file systems. Some file systems are good at speed. Others | 15:26 |
| ubuntourist | are good at efficient use of space. And others are good at redundancy and preservation -- making sure that if a file is damaged, the computer can make an | 15:27 |
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| ubuntourist | "educated guess" about what information went missing. | 15:28 |
| ubuntourist | The average Linux user today uses the "ext4" file system. See | 15:29 |
| ubuntourist | https://en.wikipedia.org/wiki/Ext4 | 15:29 |
| ubuntourist | So. When you are loading up your virtual machine, the disk image contains a boot sector, and a File Allocation Table with a "file system" -- probably "ext4" | 15:30 |
| ubuntourist | and, with those two pieces of information (boot sector and fie system FAT) the rest of the disk image file looks like something you're already familiar with: | 15:31 |
| ubuntourist | directories and files. | 15:32 |
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| ubuntourist | REMEMBER: ISO disk images, even though they look like ordinary files, are NOT ordinary. they are like ZIP files or tarballs but the special parts | 15:33 |
| ubuntourist | are the boot sector and the file system FAT that tells the computer how to break the file into "real" files and directories. | 15:34 |
| ubuntourist | You CANNOT just "copy" an ISO to another computer and expect to read the files in it. You cannot unpack it or unzip it or expand it. It is a special thing that must be | 15:34 |
| ubuntourist | "written" to a hard disk in a special way. (Your virtual machine software will know how to do this.) | 15:35 |
| ubuntourist | Anyway, that's all I wanted to talk about today: | 15:36 |
| tboimah | okay that was great | 15:36 |
| ubuntourist | After installing virt manager and creating an empty virtual machine, you need a special ISO disk image to be put on the virtual hard disk. This is like | 15:37 |
| ubuntourist | formatting a hard disk and copying a bunch of files all at once. Once those steps are finished, you can "boot" your virual machine. | 15:37 |
| ubuntourist | When you boot your virtual machine you will have a "virgin" operating system that you can destroy without worry. | 15:38 |
| tboimah | alright | 15:39 |
| ubuntourist | If somehing breaks, you just delete the virtual machine, create a new virtual machine, and reload the ISO disk image to get back to a "virgin opeating system". | 15:39 |
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| ubuntourist | I don't know yet if the book will have you do it, but we might try several different Linux operating systems using different ISO disk images. | 15:40 |
| ubuntourist | And, as systems administrators, eventually, you may want to create your own disk images. | 15:41 |
| ubuntourist | For example, let's say you're running a school's computer center. for four years. | 15:41 |
| ubuntourist | Eventually, you will become tired of saying "apt install most", "apt install tmate", "apt install bla-bla-blah", "useradd sysadmin", "vim /etc/profile", ... | 15:42 |
| ubuntourist | on every single machine again and again. | 15:43 |
| ubuntourist | Eventually, you'll decide "I always want these packages, these users and these configurations on ALL of my lab's computers." | 15:43 |
| ubuntourist | Well, once you have something that you think is the "perfect" set up. you can create an ISO disk image snapshot of your perfect machine, | 15:44 |
| ubuntourist | and just load the ISO disk image onto every computer. It will erase all of the old information on the computer and set up a complete environment that is identical | 15:45 |
| ubuntourist | to the environment on your perfect computer. | 15:45 |
| tboimah | wow | 15:45 |
| ubuntourist | This is also a good backup. Suppose one of your students -- or teachers -- completely mess up, and delete everything or edit files they shouldn't edit. | 15:47 |
| ubuntourist | Well, there is no way to recover their data and prgrams if no one is backing them up regularly -- we'll talk about scheduled backups later. BUT, you can at least "reset" the computer | 15:48 |
| ubuntourist | back to a "known working state" by using the ISO to erase and restart from scratch. And because you know the ISO you're working with, you will know "Oh, yes: most and tmate are already installed, | 15:49 |
| ubuntourist | and these aliases and shortcuts are already configured for every user." | 15:50 |
| ubuntourist | And NOW, I'm REALLY finished talking for today. ;-) | 15:50 |
| tboimah | Okay thanks for today | 15:51 |
| tboimah | have a nice day | 15:52 |
| ubuntourist | Good luck getting your ISO loaded onto the virtual machine. | 15:52 |
| ubuntourist | Bye for today. | 15:52 |
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| scooper | Fkoikoi | 21:28 |
| fkoikoi | yes scooper | 21:28 |
| scooper | Did you tried attempting the question on your own??? | 21:28 |
| scooper | and did you also comment those work that was done in the lab too??? | 21:29 |
| fkoikoi | no but I will do that after this | 21:29 |
| scooper | I m about to leave from here now... | 21:30 |
| scooper | see you tomorrow | 21:30 |
| scooper | ACTION signing up | 21:30 |
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