Daily builds now hybrid CD/USB images

**VinDSL** · June 16th, 2011

The daily ISOs for the Ubuntu Oneiric development cycle (and all official Ubuntu CD releases going forward)
for i386 and x86_64 platforms will be now spun as hybrid ISOs.

SOURCE: https://lists.ubuntu.com/archives/ub...ne/033495.html (ubuntu-devel mailing list)

Colin Watson cjwatson at ubuntu.com
Wed Jun 15 21:22:34 UTC 2011

As of tomorrow's daily builds, all Oneiric amd64 and i386 CD images on
cdimage.ubuntu.com can also be written directly to a USB device. You
can still use usb-creator if you need to enable persistent storage on
the USB stick, but if all you need is to install from the stick then
this simplifies the process.

There is a small size cost to this feature; part of this is partition
alignment to 1MB "cylinders" (since the image now has to simultaneously
look like a CD and a partitioned USB disk), and part of it is a second
directory tree whose size is roughly proportional to the number of files
in the image. On the server CD (and probably the alternate CD too,
though I haven't measured that), this came out to about 5MB, but as luck
would have it I found a way to save about the same amount by hardlinking
some files together, so the size there stays roughly the same. On the
desktop CD, unfortunately, we lose about 1MB (although I consider myself
to have "paid" for this by way of the 2MB or so we gained by switching
to live-build ...). If this becomes a problem close to release time,
then we may be able to shave off a bit at the possible cost of some
USB-booting compatibility on a few machines by dropping the 1MB
alignment. See the recent thread on pkg-libburnia-devel for details.

I realise that we're behind a number of other major distributions on
this. The delay was because (like Debian) we couldn't simply use
isohybrid because that would break jigdo downloads, so we had to switch
to xorriso as the CD image generator on these architectures for its new
JTE support, and by the time all that landed in Debian I didn't really
want to cram it into 11.04.

See http://blog.einval.com/2011/01/07#isohybrid_CDs for the gory details,
and thanks a lot to Steve, Thomas, and George for their hard work on
that.

Please file bugs on https://bugs.launchpad.net/ubuntu-cdimage if this
change causes the image to stop working on machines where it previously
worked.

Cheers,

--
Colin Watson [cjwatson at ubuntu.com]

HOWTO: Write Oneiric amd64 or i386 Daily Build CD/USB images directly to USB stick

Install zsync package (if missing)

Code:

sudo apt-get install zsync

Acquire zsync Daily Build ISO (choose your architecture)

Code:

http://cdimage.ubuntu.com/daily-live/current/

Update zsync Daily Build ISO (for example)

Code:

zsync http://cdimage.ubuntu.com/daily-live/current/oneiric-desktop-i386.iso.zsync

Determine where your USB Flash Drive resides, using fdisk (from a terminal)

Code:

vindsl@Zuul:~$ sudo fdisk -l

Disk /dev/sda: 160.0 GB, 160041885696 bytes
255 heads, 63 sectors/track, 19457 cylinders, total 312581808 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x90909090

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63    20964824    10482381   83  Linux
/dev/sda2       156296446   312575999    78139777    5  Extended
/dev/sda3        20965376   154189823    66612224   83  Linux
/dev/sda4       154189824   156295167     1052672   82  Linux swap / Solaris
/dev/sda5       156296448   177268735    10486144   83  Linux
/dev/sda6       310474752   312575999     1050624   82  Linux swap / Solaris
/dev/sda7       177270784   310472703    66600960   83  Linux

Partition table entries are not in disk order

Disk /dev/sdb: 3926 MB, 3926949888 bytes
121 heads, 62 sectors/track, 1022 cylinders, total 7669824 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Or, use a GUI Disk Utility (from the desktop)

Write updated ISO directly to USB Flash Drive (for example)

Code:

sudo dd if=oneiric-desktop-i386.iso of=/dev/sdb

If you feel adventurous, adding the following seems to speed up the writing process considerably

Code:

sudo dd if=oneiric-desktop-i386.iso of=/dev/sdb oflag=direct bs=1048576

Configuring the BIOS in your PC, so it boots from a USB stick, is left as an exercise in the second-order coefficient.

**coffeecat** · June 16th, 2011

I'm probably being extremely dense here, but if one doesn't use usb-creator, how exactly does one write the ISO directly to the USB drive? Tbh, I'll be glad to not have to use usb-creator. The Natty version prompts you no less than three times for your password during the process of writing an ISO to a USB that need reformatting.

**m.rankovic** · June 16th, 2011

from: http://blog.einval.com/2011/01/07#isohybrid_CDs

"What does this mean for end users?

Instead of having to specially prepare USB sticks for the installer, you can now simply use dd to write the image straight to the raw stick, e.g.:

# dd if=debian-testing-i386-netinst.iso of=/dev/sdX"

**coffeecat** · June 16th, 2011

Originally Posted by m.rankovic

from: http://blog.einval.com/2011/01/07#isohybrid_CDs

Yes, I thought it might be dd. I missed the link in VinDSL's quote of Colin Watson. Sorry about that and thanks.

**jerrylamos** · June 16th, 2011

Originally Posted by coffeecat

I'm probably being extremely dense here, but if one doesn't use usb-creator, how exactly does one write the ISO directly to the USB drive? Tbh, I'll be glad to not have to use usb-creator. The Natty version prompts you no less than three times for your password during the process of writing an ISO to a USB that need reformatting.

Coffeecat,

I use gparted to format 2 partitions on the USB, the first F32 for the image and the 2nd EXT3 labeled casper-rw for persistent. I've had trouble trying to get usb-creator to behave. Ubuntu install has screwed me up as well so I use gparted before doing an install.

I then just plain flat copy the .iso to the first partition on the USB.

I add the following to /etc/grub.d/40_custom

Code:

menuentry "Ocelot sdb1 USB" {
set isofile="/boot/iso/oneiric-desktop-i386.iso"
loopback loop (hd1,1)$isofile
linux (loop)/casper/vmlinuz boot=casper persistent iso-scan/filename=$isofile noprompt noeject
initrd (loop)/casper/initrd.lz
}

then sudo update-grub.

This has been working for me. Note you can put the .iso into a folder on the hard drive example /boot/iso which is a bit faster than the USB. In either case size of the daily build is no longer an issue. I even boot the .iso from a hard drive and install to a 2nd hard drive or a USB hard drive. I haven't tried installing to the same hard drive as the .iso is on. Chicken.

Now this is all before the changes Colin mentioned. I'm doing a zsync right now.

Coffeecat, I'd appreciate it if you could interpret colin's explanation to us ordinary testers.

Thanks, Jerry

**Grenage** · June 16th, 2011

Originally Posted by VinDSL

The daily ISOs for the Ubuntu Oneiric development cycle (and all official Ubuntu CD releases going forward)
for i386 and x86_64 platforms will be now spun as hybrid ISOs.

SOURCE: https://lists.ubuntu.com/archives/ub...ne/033495.html (ubuntu-devel mailing list)

Fantastic news, and something I've been waiting for.

**jerrylamos** · June 16th, 2011

Just did a zsync on the 16 June to a folder on the hard drive, and booted the .iso with grub2 O.K. as usual.

So I don't know what Colin & crew have done or what to do to take advantage of it?

This entry is from the usual way I boot .iso as given in my previous post. I've put the .iso on a USB and boot the same way, but so far haven't been stung by just booting the .iso from the hard drive. Famous last words.

Progress, nm applet successfully connected wireless today. It's been crashing.

I did get a lightdm crash but it's still running. Crash report in process...launchpad bug #796272.

Jerry

**coffeecat** · June 16th, 2011

Originally Posted by jerrylamos

Coffeecat, I'd appreciate it if you could interpret colin's explanation to us ordinary testers.

I don't think it needs that much interpreting. Perhaps, like me, you missed this bit:

Instead of having to specially prepare USB sticks for the installer, you can now simply use dd to write the image straight to the raw stick, e.g.:
# dd if=debian-testing-i386-netinst.iso of=/dev/sdX

Obviously, substituting the Ubuntu ISO filename for the debian one.

**fjgaude** · June 16th, 2011

I dd copied the i386.iso daily of today to a fresh 4G thumb and when I booted the msg "no operating system", repeated over and over.

Any help? Thanks!

**jerrylamos** · June 16th, 2011

Originally Posted by fjgaude

I dd copied the i386.iso daily of today to a fresh 4G thumb and when I booted the msg "no operating system", repeated over and over.

Any help? Thanks!

I can't tell from your note whether you added the above to /etc/grub.d/40_custom?

And then did the sudo update-grub?

On the fresh 4G thumb, did you partition it with gparted and format it, first partition to F32? A fresh USB might come formatted I don't know how, example F16 which I've had no luck with.

Do note that I used hd(1,1) for the USB drive which is how it comes up on my pc. You should be able to tell from gparted whether it is /dev/sda or /dev/sdb (as mine is) or /dev/sdc which it is on another of my pc's.

Jerry