Using dotISO Files

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For General Users

Purpose

Files having the extension *.ISO may be new to some readers.

  • now available for download, to reinstall failing Windows 8, 10 or 11
  • continue to be the main format for Linux downloads

These files are essentially an image of a CD, DVD (or BlueRay ?) optical media and usually images of bootable media. dotISO files may be downloaded, saved, copied to other disks/volumes/folders etc, exactly like any other file. However, they require special processing to achieve their usual purpose of producing a bootable media

  • originally dotISO were intended for CD/DVD media
  • the same files may now be used on bootable USB/SD media
    • this requires a different program to write the media

The bootable media are typically used for one of:

  • a "live" demonstration system - often based on Linux
  • running software for backing up systems and/or data
  • installing operating systems
  • "rescue" systems
those not familiar with operating systems need to execise caution with the last two


Writing Bootable USB/SD

ISO files are typically more than 1 GB in size and will load relatively slowly from USB 2.0 media. New, quality USB 3.0 "thumb drives", of at least 8 GB capacity, are advisable and relatively inexpensive.

Cautions re SD Cards

  • even quality, fast-rated SD cards are highly dependent on the card reader used - USB thumb drives are a better choice for beginners
  • "File Explorer" might not be able to optimally reformat used SD cards. SD Card Consortium provides an App "SD Formater" for best re-formatting of SD cards

Writing ISO Files

  1. this method is relatively safe for Linux & Windows users
    • it should suceed with all dotISO files, provided that those are bootable images
  2. obtain and install "Ventoy" Ventoy
    • available for Windows or Linux
  3. as a precaution, disconnect all other USB devices from the computer
    • including scanners, mobile broadband sticks, modems etc
  4. launch Ventoy
    • select the USB/SD media to be written
    • click OK
  5. locate the downloaded dotISO file(s) on hard disk
    • drag & drop the file(s) to the removable media
    • Windows shows the two volumes on Ventoy media as the same drive letter
    • drag only to the exFAT volume

Booting Live Media

  1. take the Ventoy device containing dotISO files to the computer to be used
    • boot/reboot and go to "Setup"
    • in "Boot" tab, ensure that booting from USB HDD is enabled
      • a Ventoy device does not behave as a USB DVD
    • (optionally) make USB HDD the first boot device
      • if this is not done, the relevant Function key will need to be pressed, at boot time, to select the Ventoy device
    • save settings and reboot
  2. select required dotISO
    • Ventoy should display a menu, from which the desired dotISO can be selected
    • a dotISO can take a minute or longer to load, even on fast USB drives
    • most dotISO display some form of progress "meter"
    • a few do not

Running from Live Media

  • a session may be run indefinitely
    • any work created/edited will generally not be saved
  • a running dotISO will generally have a menu item/icon to "shutdown"
    • no additional action is required to close a Ventoy session

Getting Technical

non Windows users README

Writing Bootable USB/SD

Linux users need to execise great caution with the this procedure - an error in selecting the USB/SD device could result in hard disk partition being overwritten

Linux users can use the command

# lsblk

to cross check which storage devices are recognised

All users should cross-check which removable device is to be written by examining the manufacturer ID, partition size, filesystem type (FAT 32) reported by the Operating System

Writing ISO Files

  1. this procedure can be achieved via GUI tools
    • it shoulc suceed with all dotISO files, provided that those are bootable images
  2. obtain and install a suitable program
    • unetbootin is one of the better known
  3. ensure that the USB/SD media to be used is formatted FAT 32
  4. as a precaution, disconnect all other USB devices from the computer
    • including scanners, mobile broadband sticks, modems etc
  5. launch unetbootin
    • locate the downloaded dotISO file on hard disk
    • select the USB/SD media to be written
    • click OK

Burning Bootable CD/DVD

  1. this will be the simpest and most reliable approach for beginners
    • virtually any computer now in use can boot CD/DVD
    • most OS have suitable software for burning CD/DVD
  2. a common mistake made by novices is to use their favourite burner software to copy a *.ISO file to a blank CD/DVD - incorrect as explained at http://www.puppylinux.com/cd-puppy.htm
Correct procedure is to use a special option in the burner software to "burn CD ISO image" or "burn DVD ISO image".

Windows 7

  1. via Windows Explorer is the simplest procedure for beginners
    • locate the ISO file in Windows Explorer and right-click it. You will get various options
    • click on 'Open with' then choose 'Windows Disc Image Burner' to produce a bootable CD/DVD
    • to be prudent, tick the 'Verify disc after burning' box
  2. popular burner software Nero has a similar option. Detailed procedure is available at the following site: http://partedmagic.com/doku.php?id=creating_the_livecd_with_nero
    • simply select your dotISO file in lieu of partedmagic.iso
  3. if none of the above options are available get the product ftp://terabyteunlimited.com/burncdcc.zip and install that
It makes the operation foolproof, because its only function is to burn ISO images to CD/DVD

Other OS

  1. most Linux will include CD/DVD burning software such as k3b, XFreeBurn etc, which include the function to "burn CD ISO image"


Choice of Optical Media

  1. dotISO disks must be "bit-perfect"
    • avoid using cheap media blanks that are sold primarily for audio/video use
    • setting a slower burn speed might produce more reliable results when using untested burner/media combination
  2. dotISO images that are smaller than 700 MB may be burnt to DVD media
    • most burner software will cope with this
    • doing so is likely to result in the media reading somewhat faster than would be the case with CD media and this can be advantageous for the uses described above.
  3. dotISO images >700 MB but << a full DVD of 4.3 GB will often be encountered
    • these must be burned to DVD media
  4. dotISO images > a full DVD size of 4.3 GB are occassionally encountered
    • these can be burned only to dual-layer DVD media
    • such media is relatively expensive and
    • not all releases of burner software handle it reliably
  5. avoid burning dotISO to 80 mm diameter mini-CD/DVD
    • from which the read process would be relatively slow
    • not all releases of burner software handle it reliably


Strictly for Geeks

SD Cards

If an SD card is to be re-used then the following preparation should be followed

  1. attach the card to a Linux PC via a card reader
  2. use # lsblk
    • to identify the device as sd(x)
  3. run # dd if=/dev/zero of=/dev/sd(x) bs=1M count=8
    • to zero the first 8M
    • this is the notional "first cylinder" used by Windows devices and to which they might store filesystem metadata

Experienced users tend to use "dd" to write ISO images to SD cards

  • SD cards use very large block sizes and will write slowly with the common 4 kiB block size
  • small block sizes might also cause unnecessary write cycle - the mortal enemy of flash memory devices

Therefore run # dd if=<path to ISO image> of=/dev/sd(x) bs=4M

  • to write the image.

Using/Creating ISOhybrid Files

This task is for intermediate/advanced users

Overview

Some dotISO files are now being provided as "ISOhybrids"

  • which have the main advantage of typically booting much faster from USB/SD devices
    • because most OS use conservative settings to boot USB/SD devices, in order to cope with older/buggy BIOS
  • boot speed is also highly dependent on the "Class" of SD media and (probably) unstated/indeterminate grade of USB "thumbdrive"

ISOhybrids may also be burnt to conventional CD/DVD/Bluray optical media, or written to USB/SD media, as in general/intermediate procedures above

  • hence the "hybrid" descriptor
  • but require the alternative procedure below to achieve faster performance from USB/SD devices

Hybridisation

  1. this procedure may be skipped, if the ISO is known to already be hybridised
  2. dotISO of unknown type may safely be converted to hybridISO via the program "isohybrid"
    • the conversion adds a few tens of kB, if the ISO is not already hybridised
      • which may push the ISO beyond the maximum capacity of optical media
      • alhough these ISOhybrids could still be written to USB/SD media, as in intermediate procedures above, or advanced precedures following.
    • it makes no perceptable difference if the ISO is already hybridised


execise great caution with the following procedure - an error in selecting the USB/SD device could result in hard disk partition being overwritten

Writing ISOhybrids

  1. as a precaution, disconnect all other USB devices from the computer
    • including printers, scanners, mobile broadband sticks, modems etc
      • any of which could include "storage"
  2. verify the drive letter/number of the USB/SD media
    • in Windows use "Computer" menu and open the drive
    • in other OS use "My Computer", hdparm, fdisk etc
    • check by manufacturer ID, size, partitioning etc
  3. the partitioning/format of the USB/SD media to be used is probably immaterial
    • if in doubt, format the single/first partition as FAT 32
  4. launch a program for direct writing disk images of storage media eg
  5. more detailed instructions are at:

http://en.opensuse.org/SDB:Live_USB_stick#Bootable_USB_from_DVD_or_Net-install

execise great caution with the above programs - an error in selecting the USB/SD device could result in hard disk partition being overwritten

Booting from Media

Booting from Removable Media


--Rpeters 12:09, 24 August 2012 (EST) --

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