VirtualBox client CentOS can’t boot up with error message:

1. [FAILED] Failed to start Virtual Machine and Container Registration Service.
2. [FAILED] Failed to start Login Service.
   

Solution

Disable SELINUX config with the following steps during boot up sequence:

1. During Grub boot up stage, press 'e' to edit grub sequence;
2. Add systemd.unit=rescue.target to the end of line with linux16 and boot with rescue mode;
3. Press ctrl+x to continue boot sequence

Config

• CentOS 7 3.10
• VirtualBox 6.0.10

Tricks

• The cause of this boot up issue was difficult to found and the original setting of SELINUX was ‘permissive’ not ‘enabled’. However, this issue may also be owing to bugs in VirtualBox 6.
• During boot up process, by default the boot up is quiet, i.e. no system message will be displayed, only the boot up progress bar is seen. However, pressing Esc key will let you see the detail boot up messages.

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Background

After installing WP Health, it’s shown that both MariaDB 5 (a default replacement of MySQL for CentOS7) and PHP5.6 are obsolete, i.e. no more formal support and no security patches will be released. It’s suggested to upgrade at least to MariaDB10 and PHP7.

Apart from security and support concern, it’s known that PHP7 has better performance than PHP5.

Issue

After upgrading, either the Virtualmin has problem in displaying submenu on the left panel or there’re “Internal Server Error” on some WordPress sites. It’s found out that during yum update MariaDB, it’s required to remove the old MariaDB5, however, for packages dependency needs, yum will at the same time remove Postfix and Virtualmin-base. If these 2 packages are reinstalled after upgrading to MariaDB, then WordPress has problem.

Solution

Use rpm -e –nodeps to skip removal of Postfix and Virtualmin-base.

Tricks

After removal PHP5.6, list out all the related packages, e.g. php-mysqlnd, php-gd, etc. depending on my case, there’re some others. All these have to be reinstalled after installing PHP7.2 base package.

For upgrade of PHP7, never upgrade to the lastest PHP7.3 as some of the PHP packages do not have PHP7.3 compatible rpm, only have PHP7.2 compatible rpm. There’re many CentOS PHP7 upgrade info. on the web, but some are not good, after try and error, I use TecAdmin.net’s advice and got no problem.

Config

• CentOS: 7.6
• Virtualmin 6.06
• WordPress 5.1
• MariaDB: 10.1

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“The selected virtual machine is inaccessible. Please inspect the error message shown below and press the Refresh button if you want to repeat the accessibility check.” After saving states of all virtual machines of VirtualBox running on Mac, rebooting the Mac host without any issue. Then it was a big surprised that all virtual machines are inaccessible. Not only the virtual hard disks, but all the virtual machines files.

Solution:

This case was caused by previously renaming the external SSD storing the virtual machine files. After renaming back to original disk name, still have to

• Remove the virtual machines and Add them back to VirtualBox by going to the VirtualBox application top bar
• Choose Machine -> Add
• Select the file with .vbox (that’s the virtual machine file, not the .vdi or .vmdk). In case, the there’s unexpected quit of VirtualBox, the .vbox may be corrupted, then it is necessary to rename the .vbox-prev to .vbox

Tricks:

• It is not easy to recognise that the issue was caused by renaming the path (in this case, the SSD disk) of the virtual machine as not until restarting VirtualBox, it is not observed there is any error on the virtual machines.
• Even after renaming back the path to the original one, VirtualBox still shows inaccessible virtual machine. The suggested solution of clicking the Refresh button located at bottom left cannot fix the problem. (Don’t know why Oracle is so stupid to suggest this!)
• The Machine -> Add appears only at the top bar of VirtualBox application, but not appear at the top bar of Oracle VM VirtualBox Manager
• It is easy to misinterpret the error message that it was due to inaccessible storage and it would be tempted to create new VM and access the same original storage, but it is not good in the sense that the virtual hard disk is located under the old VM’s directory.
• Mac users always have TimeMachine backup for the virtual machines, in such case restoring the VM directory is wasting time.

Config:

OS X           10.12.1

VirtualBox   5.0.28

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Deleting the oldest snapshot of virtual machine in VirtualBox is often difficult, sometimes there is error with detail “more than one child hard disk”.

Solution:

Open VirtualBox control panel, select:

File->Virtual Media Manager

click on the Virtual child hard disk within the appropriate virtual machine (don’t check for other non-appropriate virtual machines) one by one, at the lower part of the panel, there are some information about the hard disk, “Type”, … “Attached to:”, etc., normally all child hard disk of the same virtual machine should be “attached to” the name of the Virtual machine, but at the problem child hard disk, the info. about the “Attached to” is Not Attached, then you can select “Remove” to take it out, if ask whether to “Keep” or “Remove”, for safety, you can keep the file, then go back to Snapshots to remove again the snapshot, the error should be gone.

Tricks:

• Similar error occur only on deleting the oldest snapshot but not recent snapshots.
• It is dangerous to just remove the hard disk file stored in the Snapshot directory of the virtual machine, and indeed remove snapshot process of Virtualbox is not just removal of virtual disk file, but some kind of merging the appropriate snapshot content with the current virtual hard disk. Inappropriate removing any snapshot files would be a nightmare to restart the virtual machine.
• In many forums, it is known that the error of deleting the first snapshot is a bug of VirtualBox for quite some years since ver. 3.x, but it still exists till this version 5. A shame to the technology giant, Oracle!

Config:

VirtualBox  5.0.10r104061

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Starting Chrome in Windows 7 guest from Virtualbox happens to see only flicking windows with flashing rate around 2-4 rounds per sec.

Solution:

Turn off hardware acceleration in Chrome setting or uncheck 3D acceleration in Virtualbox.

Tricks:

When flicking occurs, you cannot start Chrome, thus no way to turn off hardware acceleration at setting. Either start Windows in safe mode, then start Chrome and change setting or shutdown windows then uncheck 3D acceleration setting in Virtualbox, and start windows again.

Config:

• Chrome 47.0.2526.80 m (64-bit) for Windows
• Windows 7 Service Pack 1
• Virtualbox  5.0.10

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Trying to set up another Drupal site on free tier of Amazon cloud, the feeling and setup are all good! After setting up LAMP stack, suddenly received an email from Amazon that I recently reached a limit on the volume of email I was able to send out of SMTP port 25 on my instance. I was shocked on the one hand worrying about if my webserver was compromised and on the other hand questioned why the Security Group pre-set by Amazon EC2 did not work according to my expectation. It led me to enable the firewall of my linux, i.e. CentOS 6.

Issue:

Although open the specific port for webmin on the linux firewall, I forgot to open the SSH port 22, it caused a tragic connection lost to the virtual machine. That is, it could neither be connected through SSH login nor webmin. That may be caused by incorrect set up of the firewall rules such that the specific port for webmin was unexpectedly blocked.

Solution:

• Terminate the virtual machine and set up a new instance.
• Use webmin’s standard linux firewall rules and add some ports, but not other rules.

Configuration:

• EC2 micro-tier
• CentOS 6.4
• Webmin 1.620

The post Amazon EC2 Total Connection Lost appeared first on LarryLai.

As more depending on iPad (now iPad mini), few tasks are to be done on my current notebook PC, Acer Aspire 1810Z running Windows 7 Home Premium.

Rebuild desktop PC, HP from previous CentOS 5 to OpenSuse, I want to have a virtual Windows for some special situations, e.g. web applications need to run on MS Internet Explorer. Actually, still most payment gateways connected to the Hong Kong Government’s agencies need IE to proceed the payment transactions even though some of them allow you to make booking reservation online with other browsers.

Choosing Oracle VirtualBox as the virtualization platform rather than OpenSuse’s preferred Xen and KVM tools because I used to running my virtualized guest OS’ on VirtualBox for quite some years. My CentOS guest has been running the main webserver Apache on VirtualBox deployed in my Mac Mini for 2 years.

Methodology for the migration is using Windows 7 built-in backup system utilities to backup the whole system to external disk, and made a ISO bootable file to be used as the virtual boot CD in VirtualBox.

Issues:

1. Making VirtualBox to operating properly in OpenSuse was the 1st issue. After installation, only the root user could start it, but not other normal users. I run my desktop as normal user instead of root just for security reasons.
2. Could not restore the Windows backup image to a new virtual disk with error stating that no valid disk is connected to the system. Actually, by inputing Windows command “DISKPART” followed by “LIST DISK”, the newly created disk was shown. Even though using Gparted utility to make partition table on the disk and format the disk to ntfs file system. All these did not work.
3. After recovering from the backup image, still could not kick of the Windows VM. After seeing the Windows 7 logo, total black screen and nothing happened.

Solutions:

1. Run VirtualBox as non-root user.
   1. Install VirtualBox from Oracle site rather than from OpenSuse software repository. Also install Oracle VirtualBox extension Pack.
   2. Change permission of /dev/vboxdrv to allow other users to access this driver.
2. Select SATA controller to configure the virtual system disk to run Windows though transferring of files is fine using other types of storage controllers, say IDE. Configure a larger disk, say 160GB. Using a disk with small capacity say 40GB would cause the error mentioned above.
3. Configure VM with 2 processors instead of 1.

Tricks:

1. After installing VirtualBox from Oracle site, still some minor errors occur. Need to install/update some software in OpenSuse to clear the errors.
2. Even though the windows image is small, say 30GB, but I guess the original disk being backup was 120GB, then the target disk should not be less than 120GB. In case no physical capacity for disk is available. Thin provisioning of disk by selecting dynamic disk space allocation in VirtualBox is good.
3. I focused on changing the video RAM allocation for the VM and unchecking 3D, 2D acceleration. All these changes suggested on the web could NOT help for this scenario.

Config:

• CPU E8400 dual-core 3GHz, with 4GB memory
• OpenSuse 12.2 (x86_64)
• VirtualBox 4.2.8 r83876, and VM configuration below:
  • Processor No =2
  • Memory = 1.5GB
  • 3D and 2D acceleration checked
• Windows 7 Home Premium

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