Nan Xiao's Blog

A system software / performance engineer's home

Tag: VirtualBox

The timezone issue of installing OpenBSD in VirtualBox

I tried to use OpenBSD in VirtualBox. During installation, it prompted me:

Time appears wrong. Set to ‘Sat Aug 19 11:56:42 +08 2017’? [yes]

Since my server is UTC+8 timezone, I select “yes”. But after rebooting, the date command showed wrong info:

Sat Aug 19 20:01:00 +8 2017
Sat Aug 19 12:01:05 UTC 2017

Actually, my current host time should be 12:01:05 UTC+8. The VirtualBox seemed consider the host time as UTC time, and added another 8 hours. After discussing in the mailing list, the correct answer was found. I should tick “Hardware clock in UTC time” in setting:


According the manual:

If checked, VirtualBox will report the system time in UTC format to the guest instead of local (host) time. This affects how the virtual real-time clock (RTC) operates and may be useful for Unix-like guest operating systems, which typically expect the hardware clock to be set to UTC.

OpenBSD should consider time reported by VirtualBox as UTC time. So if this option is not checked, the VirtualBox will report local time to OpenBSD, OpenBSD misunderstands it as UTC time and add additional 8 hour to local time. This can explain what I have seen.

Set date during OpenBSD installation.


Install VirtualBox guest additions

To use “Shared Folders” in VirtualBox, the user should install VirtualBox guest additions:

(1) Select Devices -> Insert Guest Additions CD image. If the VirtualBox prompts:

Unable to insert the virtual optical disk C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso into the machine CentOS.

Would you like to try to force insertion of this disk?

Count not mount the media/drive 'C:\Program Files\Oracle\VirtualBox\VBoxGuestAdditions.iso' (VERR_PDM_MEDIA_LOCKED).

It means the Devices -> CD/DVD DEvices already has ISO file. Please inject it, and try Insert Guest Additions CD image again.

(2) Mount the ISO file:

mount /dev/cdrom /mnt

(3) Install the VirtualBox guest additions (Take Linux as an example):

cd /mnt

You may also need to install bzip2, gcc and kernel files to install guest additions successfully. When meeting errors, please refer /var/log/vboxadd-install.log for detail info.

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