recovering LUKS encrypted Ubuntu LV Group when mounting on a different Ubuntu system

I mirror my hdd, and keep swapping them in and out of test system. Often I mirror ( using external dock, such as - http://www.ebay.in/itm/Anker-Uspeed-USB-3-0-and-ESATA-To-SATA-External-Hard-Drive-Docking-Station-/161201311080 ). This leads to an issue.

 Ubuntu during installl with luks+lvm configuration will name the vg as "ubuntu--vg". And when you plug in another drive on which ubuntu was installed, would lead to a naming conflict and failure to activate the lvm after luks open.

) Ubuntu will give you a passphrase dialog when you plug the device in (if you're in a gui) but will fail to mount after the password is entered. The reason for this is that the volume group of your old partition, and your current OS partition are the same. However, if you enter the password, it will still create a node in /dev/mapper/. If you run ls -la /dev/mapper/ you should see a luks-xxxxxx-xxxxx-xxxx or some such file. That's the mapping that was created when the password dialog failed. Note, that all the dialog did was to call: luksOpen and map it to that /dev/mapper/luks-xxx file.

1) Make sure your physical volume is available by running the pvdisplay command. It should be /dev/mapper/luks-xxx-whatever. Notice that the VG Name of both drives is the same; this is problematic and will prevent you from being able to mount the drives both at the same time (very frustrating).

2) To fix this, get the uuid of the volume by running "pvs -o +vg_uuid". The uuid will be the value displayed all the way to the right, containing 7 dash-delimited values. Copy those somewhere as we'll be using them in the next step. DO NOT CONFUSE UUIDS AND COPY DOWN THE WRONG ONE. Only copy the one for your current luks-xxx-whatever device.

3) Change the volume group for your old disk by running the following command "vgrename UUIDOFYOURDISKHERE oldhd" You can change the "oldhd" to whatever you want so long as it's differing from the volume group name of your current disk. Performing this step removes the conflict with volume group names which will allow you to now make volumes available.

4) Run the command "vgchange -a y" to make the volumes active.

5) Create a mount point somewhere, for example create mount point /mnt/oldhd/ by running mkdir /mnt/oldhd/.

6) Now, mount the root partition of the oldhd volume group by running the following command: "mount /dev/oldhd/root /mnt/oldhd"

7) You should now be able to cd into /mnt/oldhd and acc

reference:

http://www.reddit.com/r/Ubuntu/comments/1wjhzf/recover_luks_encrypted_ubuntu_lv_group_from/

Shrink VMs on virt-manager/KVM

  I tend to use rsync to backup my system ( including VMs) thanks an anoying bug[1] . Turns out, this would sync the entire sparse file, expanding from 11gb on disk to 64gb on target system.

 To "fix" this I now use qcow2 for disk image, based of instructions from here[2].

•  Move existing images to qcow2 , if not done. This also would allow us to use snapshots via virt-manager [3]

# convert existing raw images to qcow2 image $ qemu-img convert -O qcow2 $ mv orig.img orig.img.bak $ mv new.img orig.img # assuming the first device marked raw is the hdd $ sed -i 's/raw/qcow2/' /etc/libvirt/qemu/orig.xml

• Fill VMs with zeros to allow them to be compressed

$ dd if=/dev/zero of=/mytempfile $ rm -f /mytempfile

• Shut down the VMs, and run from host 

$ mv original_image.qcow2 original_image.qcow2_backup

$ qemu-img convert -O qcow2 original_image.qcow2_backup original_image.qcow2

[1] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1259829
[2] http://www.jamescoyle.net/how-to/323-reclaim-disk-space-from-a-sparse-image-file-qcow2-vmdk
[3] http://www.phoronix.com/scan.php?page=news_item&px=MTQ0NjM

Windows 7 on KVM - High CPU usage on host while guest is idle

remove the usb tablet device, and the cpu usage drops .

reference: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=672720

Unity vs gnome-shell : the small things - status tray

Unity vs gnome-shell : the small things - status tray 

gnome-shell status tray is an interesting implementation , written in js. Consequently, easy to learn, write for, and extend. What does bother me here, is the focus steal.

When a user click on a status tray icon and moves the cursor down diagonally, focus will switch to next nearest tray icon. This is rather annoying, and more so due to the space between the menu and the icon.

A bug has been filled for this ( gtk menu grab ? ), which Iam unable to locate.

With Unity, this is not seen as the icons are smaller and consequently user has very minimal chance of switching applet when a user moves the cursor diagonally down. Seems to me a good implementation of UI ( or is this fitt's law ?)

edit: gnome-shell has made the larger, thus fixing this issue for me.

Closing apps in "window pickermode " in gnome-shell

One of the problems when working with touch screen is closing apps in window picker mode. I say,  add a "trash can" to the dock where I can drag and drop applications to close. This would only be visible in window picker mode.

Thoughts?

Tablets : Unity and gnome-shell

I have thinking about writing this down for quite a while, my experiences with WeTab running Unity and gnome-shell.


Unity seems a good interface for a netbook ( I have not used this on 396.2mm laptop yet). The chink being, poor Tablet support. On install, I had setup auto-login, and was presented with the desktop and launcher. Opening up an app, and maximizing it hides the launcher, which I found really hard to find again. The scroll bar is something I was unable to find in applications, and Touch gesture has not been implemented yet for scrolling. Otherwise, a good deal.


gnome-shell is one the best interface I have seen ( I have limited exposure to KDE ) , when it comes to touchscreen devices. The toggle buttons are huge and easy target to access. The application switch is trivial, as "Activies" is always visible. Switching workspace is easy, not that it is not completely hidden off during "Window Picker mode. The notification is one thing, which I easily miss out on and consequently every action which needs my attention. I would be really happy, if I could show/hide notification from system menu's notification toggle switch.


The good about both, Tiling and "auto-maximization" of Windows works good. We could try working with a Tiling window manager on Tablet, with multiple desktop. What we would need is Thumb keybord, or a keyboard which can stick to one corner assuming we use a single hand to type.


The bad about both, we need bigger fonts and target area. X still lacks a sound multi-touch foundation in most distribution. Scrolling is still a bit painful on touch devices, without gestures such as two finger scroll. Will everyone have a multitouch device ?  gnome-settings-daemon xrandr plugin should also probably rotate the Touchscreen input.



reference:
https://desktopsummit.org/program/sessions/towards-multitouch-gnome-shell
http://live.gnome.org/GnomeShell/Design
http://unity.ubuntu.com/projects/
http://who-t.blogspot.com/2011/12/multitouch-patches-posted.html
https://wiki.ubuntu.com/Multitouch
https://bugzilla.gnome.org/show_bug.cgi?id=652247
https://bugzilla.gnome.org/show_bug.cgi?id=659498

Not so mad over donuts - a terribly written review of a bad experience

You can pick any colour for your car,  as long as it is black.  So says,  mad over donuts. 

  I tend to like plain donuts,  and one thing which is which comes out of kitchen is a plain freshly prepared hot crunchy donut. The one thing which mad over donut refuses to sell is a freshly prepared hot crunchy plain donut. For some reason whatever else is being sold on,  tastes stale to me.

Speaking over there hot line does help much,  except for the usual corporate rant of standardization and the inability for the customer to choose.

   This sucks,  and leaves a terrible bitter bad taste in my mouth for not so mad over donuts.