Grid Infrastructure Removal / ASM disks Oracle VM box

These notes from Oracle Base can be used to remove a failed Grid Infrastructure install but I have added the piece below as I hit a problem with ASM disks on Oracle Virtual box.

https://oracle-base.com/articles/rac/clean-up-a-failed-grid-infrastructure-installation

Following a failed RAC attack install, tried to delete and then add the asm disks.

However, Oracle Virtaul box holds onto the disk information and won't let you add a disk with the same name. The solution is to use vboxmanage from the cmd prompt.

In the example below, removes the 5gig ASM disk.

C:\Program Files\Oracle\VirtualBox>vboxmanage list hdds

UUID: a35460c0-eef6-4bc5-a706-66dbddce04d7
Parent UUID: base
State: inaccessible
Type: shareable
Location: C:\racattack12c\asm1.vdi
Storage format: VDI
Capacity: 5120 MBytes
Encryption: disabled

UUID: 266df39c-8e4b-40cf-8c34-500d69ee1ab9
Parent UUID: base
State: created
Type: normal (base)
Location: C:\racattack12c\collabn2.vdi
Storage format: VDI
Capacity: 30720 MBytes
Encryption: disabled

UUID: cfec563f-a1a2-489c-922c-808fbaa3e984
Parent UUID: base
State: created
Type: normal (base)
Location: C:\racattack12c\collabn1.vdi
Storage format: VDI
Capacity: 30720 MBytes
Encryption: disabled


C:\Program Files\Oracle\VirtualBox>vboxmanage closemedium a35460c0-eef6-4bc5-a706-66dbddce04d7 --delete

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

C:\Program Files\Oracle\VirtualBox>vboxmanage list hdds

UUID: 266df39c-8e4b-40cf-8c34-500d69ee1ab9
Parent UUID: base
State: created
Type: normal (base)
Location: C:\racattack12c\collabn2.vdi
Storage format: VDI
Capacity: 30720 MBytes
Encryption: disabled

UUID: cfec563f-a1a2-489c-922c-808fbaa3e984
Parent UUID: base
State: created
Type: normal (base)
Location: C:\racattack12c\collabn1.vdi
Storage format: VDI
Capacity: 30720 MBytes
Encryption: disabled


--Syntax to resize disk

C:\Program Files\Oracle\VirtualBox>.\VBoxManage.exe modifyhd "C:\Users\206545\VirtualBox VMs\collabn1\collabn1.vdi" --resize 20480

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%

Headless

In the good old days, most Unix boxes needed to have a keyboard, video and mouse plugged in or they got most upset. One solution is to use KVM over IP from the likes of Avocent. You plug a dongle into the back of the server and use the network to access the box remotely.

Another option is to go headless (needs some config changes) by enabling ssh, VNC, etc then disconnecting the monitor, keyboard and mouse. Power up a second computer on the same network, start the ssh client and log on to the headless server. You will find little difference between working from the console and the remote access connection. I only mention this as it a term a lot of IT people 
never come across. In the Windows world there is something called "Server Core" installation and I think that is the closest you can get to a headless server. If anyone with a Windows background would like to enlighten us please feel free.

One thing I would advise is to fit your racks with switched rack power distribution Units (PDUs) to provide advanced load monitoring combined with remote on/off switching control of individual outlets for power cycling, delayed power sequencing, and outlet use management. At least then 
you can try the switch it back off and back on again approach (handy on Sunday mornings or 3am call outs) but be aware this is last resort, always shutdown gracefully if you can.

Guest Additions - Oracle VM Box Linux

Notes for Guest Additions after installing Linux on Oracle VM Box.

Downloaded the .iso image from here :

 http://download.virtualbox.org/virtualbox/5.2.6/

" Guest Additions are designed to be installed inside a virtual machine after the guest operating system has been installed. They consist of device drivers and system applications that optimize the guest operating system for better performance and usability."

Check your version of virtualbox to match the guest additions i.e. for me 5.2.6

Rather than create a virtual cdrom drive for the .iso file used WinSCP to copy onto 
Linux machine. From that directory used the following :

[root@collabn1 guest]# mount -o loop VBoxGuestAdditions_5.2.6.iso /guest_additions
[root@collabn1 guest]# cd /guest_additions
[root@collabn1 guest_additions]# ls -la
total 49579
dr-xr-xr-x 6 root root 2226 Jan 15 13:59 .
dr-xr-xr-x. 27 root root 4096 Feb 25 14:05 ..
dr-xr-xr-x 2 root root 480 Jan 15 13:59 32Bit
dr-xr-xr-x 2 root root 480 Jan 15 13:59 64Bit
etc....
-r-xr-xr-x 1 root root 10275944 Jan 15 13:53 VBoxWindowsAdditions-x86.exe
[root@collabn1 guest_additions]# 

You can run the guest additions from there.