I created a live cd using uck and want it to boot to ram by default. How can I do this? I know I can hit f6 while booting and insert toram=yes, but like I mentioned I want this to be setup by default. Thanks in advance. Also I am a rookie when it comes to setting up ubuntu so more detailed instructions are needed.
Live CDs using file storage in RAM anyway. What specific needs do you have that can't be satisfied by the normal way live CDs mount their filesystems? Wouldn't "toram=yes" make boot incredibly slow and use more memory than the usual approach of aufs, etc?– thomasrutterSep 8, 2014 at 0:22
2He may be wanting to decompress the sqaushfs and other components to RAM so you can remove the boot media. This can be extremely helpful when USB booting a computer with limited USB ports. I wish the feature was not removed and would be added again to the Live CDs.– user344315Oct 31, 2014 at 14:24
1Chris is correct. I want to be able to remove the boot media. This will be performed on laptops that have no internal CD Rom drive. I would like to be able to remove the connection to the drive once the boot process is complete.– phifer2088Nov 12, 2014 at 8:54
I've done this before, add the
toram option to the grub/grub.cfg file, turning the
linux ... noeject noprompt --
boot line into
linux ... noeject noprompt toram --
If you've got the live iso on a usb drive with a FS that's writable it's a lot easier, just mount & edit the grub file.
If you're using a cd/dvd or just
dd'ing the iso straight to a usb then you'll have to edit the iso file before writing it, changing the grub file first and then write to cd/usb. I once found a nice little gui program that could do that, could've been
isomasterbut not sure. Or extract files -> edit -> make new iso with anything like mkisofs, k3b, brasero, etc.
(FYI, I can't recommend
dd'ing an iso to usb, less than optimal and shreds the usb's MBR/fat)
toram option is different from the regular overlayfs (formerly aufs?) that all Ubuntu (all Debian too?) live iso's use. This option copies all the needed data from the cd/dvd/usb into ram, so you can remove or edit the cd/usb, and generally run with ram FS read/write speeds (+2GB/sec) instead of cd/usb speeds (1-10MB/sec). But the expense is using up about a GB of ram.
All live CDs "boot to RAM".
That is, for any volatile storage they use RAM.
This is technically achieved using a union filesystem such as aufs which allows you to mount a read-only filesystem (eg, the CD) and combine it with free RAM to enable writes, but the writes are gone when the computer is rebooted. This may also be combined with a compressed filesystem (such as squashfs) so that the read-only filesystem can be compressed and thus fit more data.
If you have any specific needs in terms of how you want to mount the filesystem, you'll have to be more specific.