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.

The post CentOS VM Client Can’t Boot Up appeared first on LarryLai.

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

The post Centos7 Virtualmin Upgrade PHP7 MariaDB appeared first on LarryLai.

when launching iTunes, it closed immediately after clicking the icon and appeared in half a second, then error screen appeared to ask for “ignore”, “report”, etc.

Solution:

1. Finder -> Applications -> iTunes.app
2. right click -> Get Info
3. Expand “Sharing & Permissions”
4. click bottom right lock icon and input admin password
5. select system permissions
6. click bottom wheel icon and select “Make system the owner”
7. install the latest iTunes pkg

Tricks:

• Without step 6 above, no matter how uninstall, remove iTunes.app and reinstall the latest version, it will fail to restore it properly.
• System always complains when simply removing iTunes.app by stating that iTunes is required by MacOS.
• Even login as root in Terminal command, the directory iTunes.app cannot be removed.
• Asking Apple support through discussions.apple.com, people only suggest reinstall the latest version of iTunes but no one suggest checking wheel icon under Sharing & Permissions of Get Info window.

Config:

• MacOS: High Sierra 10.13.2
• iTunes:  12.7.2.60

The post Cannot launch or remove iTunes from Mac High Sierra appeared first on LarryLai.

When open an email box, error appeared on iPhone warning: Cannot verify Mail Server Identity. One solution for this problem is to delete that mail account on iPhone and add it back. However, after account deleted, I could not add it back with the following warning:

Mail Account already exists

Solution:

Logout iCloud on the iPhone

Add the deleted mail accounts

Tricks:

In previous version of iOS, when it showed that the system could not verify the mail server, it was easy to fix by accepting the certificate of the mail server. In my case, the certificate was expired, and I did not want to pay for SSL certificate renewal.

After deleting the mail account, actually it will not be listed on the account list. Thus, there is no clue why the error message was prompted.

Config:

• hardware: iPhone 6S
• iOS:  11.2.1

The post Mail Server Already Exists error iPhone iOS 11 appeared first on LarryLai.

After updating iOS from version to 11, there are some installed apps not ready for this version.

The worst is that I stored all important passwords in an app called Keyring, but after iOS update, I cannot get any of the stored password because of incompatibility of this app with this iOS ver.

Solution: NO

The post iOS 11 incompatibility appeared first on LarryLai.

After moving mounted volumes from Qnap NAS to iMac as host with CentOS as client, the directory and file ownership cannot be changed to Apache at the client side. No matter using root or user privilege to command the chown.

Solution:

Add the following in iMac’s /etc/exports:

[nfsshare] -rw -maproot=root:wheel

Tricks:

-maproot directive can pass the root control from nfs host to client, without it even changing the directory access and file permission to 777 in host, or changing the mount options at client cannot solve the issue.

Config:

• OSX:        10.12.3
• CentOS:   7.3

The post Cannot Change Ownership on NFS Files appeared first on LarryLai.

“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

The post VirtualBox VM Inaccessible on Mac appeared first on LarryLai.

Just bought a Wacom Intuos Draw CTL-690, and want to install a note taking app with drawing feature in iMac running OSX Mavericks, found a good one – MS OneNote, but it only support OSX 10.10 or above. Being aware of the possibility that the latest OSX Sierra does not fully support old Adobe CS5.5 Master Collection, I tried to upgrade to OSX Yosemite. After downloaded Yosemite install package on the web as it is unavailable on Apple’s support site any more.

There was error after verifying the system when running the Yosemite installer suggesting contact AppleCare.

Solution:

Directly upgrade to OSX 10.12 Sierra. There is some little problem with Photoshop. Need to install JavaSE again as instructed by Photoshop after upgrade.

Tricks:

• It is good practice to backup the old OS with Time Machine for Mac even though in my case, there is no need to restore to original OS version.
• If upgrading to Sierra has potential application incompatibility issue with new OS, I think there still may be some with Yosemite or El Capitan, why not give Sierra a try as it is 10.12.1 not the xx.xx.0 version.

Config:

• OSX 10.9.5 -> OSX 10.12.1
• Photoshop  12.1

The post Mac OS X Maverick Upgrade appeared first on LarryLai.

After installation of Android Studio, the Android Virtual Device (AVD) Manager cannot be started unless the running virtual machine (irrelevant to Android Studio deployment) in VirtualBox is shut down.

Solution:

1. Instead of creating virtual device, deploy physical Android device, (actually I’ve tried this approach) e.g. Samsung old or obsolete model in case you don’t want to spend too much money.
2. Install Genymotion which is also rely on VirtualBox, thus there is no conflict between this emulator with the other existing emulator from VirtualBox.

Tricks:

The AVD manager of Android Studio could not start because there is conflict between Android Studio’s emulator module with VirtualBox.

Config:

• Host OS: OpenSUSE 13.2
• IDE: Android Studio 2.1
• VirtualBox: 5.0.18
• Genymotion: 2.6.0

The post Android Studio: Cannot Start AVD Manager appeared first on LarryLai.

OpenSUSE suddenly could not boot to GUI mode, but being kicked out to recovery mode with the CLI mode with the warning of something like no space to write on device, and the hard disk activity light was unexpectedly always on.

Solution:

• At the recovery mode, login as root and delete some snapshots.
• Execute “snapper ls” to get the snapshot numbers
• Execute “snapper delete [start number] – [end number]”
• Reboot

Tricks:

1. This issue probably occurs only on linux system with btrfs partition in which snapshots are automatically generated. Thus, it should be paid extra care to decide whether to use traditional ext3 or ext4 instead of the default partition option: btrfs suggested by OpenSUSE during installation.
2. When typing “df -h”, the storage usage seems to be normal. No storage or any partition full could be noticed.
3. When hard disk activity light always on, it seems that something related to hardware is wrong but actually it doesn’t.
4. My partition config. fully agreed OpenSUSE suggestion that btrfs for / directory and xfs for /home directory. Yesterday, due to some video files transfer from desktop PC to iPhone using FTP, I setup FTP server on desktop using proftpd, the default directory on server side is /srv/ftp. Probably the new video files are so large that btrfs generated large snapshots under / directory.

Config:

• OpenSUSE 13.2
• KDE4 1.0

The post OpenSUSE Boot Up Issue appeared first on LarryLai.