From MEPIS Documentation Wiki
Simple way to boot MEPIS from CD and yet have it quick and use CD for other things.
When this helps
- You want to experience MEPIS speed without installation. With fromiso cheatcode, you can boot MEPIS from the Live CD, yet read most data from a copy of this CD stored in one file on your harddisk. This makes it nearly as quick as your MEPIS will be after installation.
- You want to backup your data before installation. After boot with fromiso cheatcode, you can eject the CD and do e.g. backups using K3b.
How to do it
- Copy (or just move, if you burned the CD yourself) your MEPIS CD iso image to e.g. C:\xxx\mepis.iso or /home/xxx/mepis.iso (use "mepis.iso" or any other short name to make it easier to type it when you reboot, "xxx" stands for whatever folder you choose to save the file to)
- Boot from the physical CD and type a cheatcode "fromiso=/xxx/mepis.iso" at the initial screen (you don't need to specify the name of the disk/partition, the system will search automatically for the file)
How it works
Your CD will just serve you as a bootloader. This way you do not have to install GRUB. After boot, all 'CD reads' are served from the harddisk copy instead.
- Partition holding the CD iso image gets a bit 'blocked', it is mounted read-only at /isosrc. You do not have to specify which partition it is, boot system will search all around. You can remount this partition read-write if you want. But it would be quite risky to resize this partition during install.
- Cheatcode specifies a name within partition, and the example above expects /home to be a separate partition. If you are using the same partition for both your system and your user directories, the cheatcode is "fromiso=/home/xxx/mepis.iso". See output of the mount command or look at the fstab file - if /home is not mentioned there, this is the case.
- Using your old OS, you downloaded MEPIS ISO and burned it to CD.
- You booted from the CD. You like it and would like to install it. There are however two issues:
- you would like to see MEPIS at full speed - now it is slow due to CD
- you would like to backup your old data before touching your disk
- Back in your old OS, you still have that MEPIS ISO image used to burn the CD. Now you just rename it to something simple and move it to directory with simple name.
- Boot from the CD again, now using the fromiso cheatcode as described above (you have to enter the file location by hand). MEPIS is fast now! You can eject the CD and do backups of your old OS.
- Reboot from the CD once again, now without the fromiso cheatcode. Now you can resize partitions holding your old OS and install MEPIS.
Of course, there are many possible shortcuts in this scenario. With future steps in mind, you can store the ISO image directly to some easy-to-type location. Or you can move it while first running MEPIS (if you dare to mount the partition read/write). Or you can copy the CD image directly from /dev/cdrom to file (if you burned the CD on another computer). If you do not need to resize partition holding the CD image, you can boot the CD once only.
Why to backup this way
It is of course quite possible to backup most of your data directly from your old OS. Using the here described method however may have some advantages:
- System being backed up is not running, so is may be easier to take a snapshot of some system files (or to access them at all).
- MEPIS Live CD may provide you better tools than your old OS.
- MEPIS Live CD may provide you better drivers for your CD/DVD burner.
One obvious disadvantage is that the ISO file itself may become part of the backup, making it bigger (if you e.g. backup your partition as one big compressed file). If you have this problem, you could perhaps save the Live CD ISO image file on an USB stick instead.
How to use no CD at all
It also possible to boot from a downloaded ISO without ever burning a CD (maybe using the fromiso cheatcode). See Boot from ISO for instructions.