Compressing a VirtualBox VDI file for a Windows guest running on a Linux Host

Recently, I had a situation where my the VDI files for my Windows 10 virtual machine expanded in size all of a sudden and I needed to reduce them. My downloading maps for use with Routebuddy may have been the cause so I moved the ISO installation files onto the underlying Linux Mint drives. With that space, I then set to uncovering how to compact the virtual disk file and the Sysinternals sdelete tool was recommend for clearing unused space. After downloading, I set it to work in a Powershell session running on the guest operating system from its directory using the following command:

./sdelete -z [drive letter designation; E: is an example]

From the command prompt, the following should do:

sdelete -z [drive letter designation; E: is an example]

Once, that had completed, I shut down the VM and executed a command like the following from a bash terminal session:

vboxmanage modifyhd [file location/file name].vdi --compact

Where there was space to release, VDI files were reduced in size to return more disk space. More could be done so I will look into the Windows 10 drives to see what else needs to be moved out of them.

Migrating to Windows 10

While I have had preview builds of Windows 10 in various virtual machines for the most of twelve months, actually upgrading physical and virtual devices that you use for more critical work is a very different matter. Also, Windows 10 is set to be a rolling release with enhancements coming on an occasional basis so I would like to see what comes before it hits the actual machines that I need to use. That means that a VirtualBox instance of the preview build is being retained to see what happens to that over time.

Some might call it incautious but I have taken the plunge and completely moved from Windows 8.1 to Windows 10. The first machine that I upgrade was more expendable and success with that encouraged me to move onto others before even including a Windows 7 machine to see how that went. The 30-day restoration period allows an added degree of comfort when doing all this. The list of machines that I upgraded were a VMware VM with 32-bit Windows 8.1 Pro (itself part of a 32-bit upgrade cascade involving Windows 7 Home and Windows 8 Pro), a VirtualBox VM with 64-bit Windows 8.1, a physical PC that dual booted Linux Mint 17.2 and 64-bit Windows 8.1 and a HP Pavilion dm4 laptop (Intel Core i3 with 8GB RAM and a 1 TB SSHD) with Windows 7.

The main issue that I uncovered with the virtual machines is that the Windows 10 update tool that is downloaded onto Windows 7 and 8.x does not accept the graphics capability on there. This is a bug because the functionality works fine on the Windows Insider builds. The solution was to download the appropriate Windows 10 ISO image for use in the ensuing upgrade. There are 32-bit and 64-bit disk images with Windows 10 and Windows 10 Pro installation files on each. My own actions used both disk images.

During the virtual machine upgrades,most of the applications that considered important were carried over from Windows 8.1 to Windows without a bother. Anyone would expect Microsoft’s own software like Word, Excel and others to make the transition but others like Adobe’s Photoshop and Lightroom made it too as did Mozilla’s Firefox, albeit requiring a trip to Settings in order to set it as the default option for opening web pages. Less well known desktop applications like Zinio (digital magazines) or Mapyx Quo (maps for cycling, walking and the like) were the same. Classic Shell was an exception but the Windows 10 Start Menu suffices for now anyway. Also, there was a need to reinstate Bitdefender Antivirus Plus using its new Windows 10 compatible installation file. Still, the experience was a big change from the way things used to be in the days when you used have to reinstall nearly all your software following a Windows upgrade.

The Windows 10 update tool worked well for the Windows 8.1 PC so no installation disks were needed. Neither was the boot loader overwritten so the Windows option needed selecting from GRUB every time there was a system reboot as part of the installation process, a temporary nuisance that was tolerated since booting into Linux Mint was preserved. Again, no critical software was lost in the process apart from Kaspersky Internet Security, which needed the Windows 10 compatible version installed, much like Bitdefender, or Epson scanning software that I found was easy to reinstall anyway. Usefully, Anquet’s Outdoor Map Navigator (again used for working with walking and cycling maps) continue to function properly after the changeover.

For the Windows 7 laptop, it was much the same story albeit with the upgrade being delivered  using Windows Update. Then, the main Windows account could be connected to my Outlook account to get everything tied up with the other machines for the first time. Before the obligatory change of background picture, the browns in the one that I was using were causing interface items to appear in red, not exactly my favourite colour for application menus and the like. Now they are in blue and all the upheaval surrounding the operating system upgrade had no effect on the Dropbox or Kaspersky installations that I had in place before it all started. If there is any irritation, it is that unpinning of application tiles from the Start Menu or turning off of live tiles is not always as instantaneous as I would have liked and that is all done now anyway.

While writing the above, I could not help thinking that more observations on Windows 10 may follow but these will do for now. Microsoft had to get this upgrade process right and it does appear that they have so credit is due to them for that. So far, I have Windows 10 to be stable and will be seeing how things develop from here, especially when those new features arrive from time to time as is the promise that has been made to us users. Hopefully, that will be as painless as it needs to be to ensure trust is retained.

A few more shell commands

Here are some Linux commands that I encountered in a feature article in the current issue of Linux User & Developer that I had not met before:

cd --

This returns you to the previous directory where you were before with having to go back through the folder hierarchy to get there and is handy if you are jumping around a file system and any other means is far from speedy.

lsb_release -a

It can be useful to uncover what version of a distro you have from the command line and the above works for distros as diverse as Linux Mint, Debian, Fedora (it automatically installs in Fedora 22 if it is not installed already, a more advanced approach than showing you the command like in Linux Mint or Ubuntu), openSUSE and Manjaro. These days, the version may not change too often but it still is good to uncover what you have.

yum install fedora-upgrade

This one can be run either with sudo or in a root session started with su and it is specific to Fedora. The command performs an upgrade of the Fedora distro itself and I wonder if the functionality has been ported to the dnf command that has taken over from yum. My experiences with that in Fedora 22 so far suggest that it should be the case though I need to check that further with the VirtualBox VM that I have created.

Controlling clearance of /tmp on Linux systems

While some may view the behaviour in a less favourable, I always have liked the way that Linux can clear its /tmp directory every time the system is restarted. The setting for this is in /etc/default/rcS and the associated line looks something like:

TMPTIME=0

The value of 0 means that the directory is flushed completely every time the system is restarted but there are other options. A setting of -1 makes the directory behave like any other one on the system where any file deletions are manual affairs. Using other positive integer values like 7 will specify the number of days that a file can stay in /tmp before it is removed.

What brought me to this topic was the observation that my main Linux Mint system was accumulating files in /tmp and the cause was the commenting out of the TMPTIME=0 line in /etc/default/rcS. This is not the case in Ubuntu and using that is how I got accustomed to automatic file removal from /tmp in the first place.

All of this discussion so far has pertained to PC’s where systems are turned off or restarted on a regular basis. Things are different for servers of course and I have seen tools like tmpreaper and tmpwatch being given a mention. As if to prove that there is more one way to do anything on Linux, shell scripting and cron remain and ever present fallback.

Restoring GRUB for dual booting of Linux and Windows

Once you end up with Windows overwriting your master boot record (MBR), you have lost the ability to use GRUB. Therefore, it would be handy to get it back if you want to start up Linux again. Though the loss of GRUB from the MBR was a deliberate act of mine, I knew that I’d have to restore GRUB to get Linux working again.So, I have been addressing the situation with a Live DVD for the likes of Ubuntu or Linux Mint. Once one of those had loaded its copy of the distribution, issuing the following command in a terminal session gets things back again:

sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda

When there were error messages, I tried this one to see if I could get more information:

sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda --recheck

Also, it is possible to mount a partition on the boot drive and use that in the command to restore GRUB. Here is the required combination:

sudo mount /dev/sda1 /mnt
sudo grub-install --root-directory=/mnt /dev/sda

Either of these will get GRUB working without a hitch and they are far more snappy than downloading Boot-Repair and using that; I was doing that for a while until a feature on triple booting appeared in an issue of Linux User & Developer that reminded me of the more readily available option. Once, there was a need to manually add an entry for Windows 7 to the GRUB menu too and, with that instated, I was able to dual-boot Ubuntu and Windows using GRUB to select which one was to start for me. Since then, I have been able to dual boot Linux Mint and Windows 8.1 with GRUB finding the latter all by itself so your experiences too may show this variation so it’s worth bearing in mind.