Thursday Mar 20, 2014

VirtualBox without GUI

I think there are 2 levels of GUI-less-ness in virtualization software like VirtualBox.
Today I want to write about 1st level of GUIless-ness in VBox.

One can use VBoxManage CLI tool or open source Web app to modify/start/stop VBox guests.
After starting up VBox guest, one can attach to guest's console remotely by using RDP tool like WIndows OS's
"Remote Desktop".

But......., you may ask,  what about if I goofed when modifying grub.conf and guest doesn't boot with default
GRUB entry? Can I attach to guest's console before grub selection screen times out?

One way to achieve this is to make BIOS screen timeout longer like:

$ VBoxManage modifyvm "OracleSolaris11_1" --bioslogodisplaytime 60000

Now, if you attach within 60 seconds , you will get this screen.

Now, if you hit F12 , you will get this. You don't do this when you edited grub.conf wrongly but I hope you get the idea.

My "Remote Desktop"'s title bar says it's localhost:3390 but it's actually tunneled to remote Solaris server. :)






Friday Feb 21, 2014

dumping SGA

If you are desperately salvaging out data or doing forensics or auditing type of job or just poking around buffer cache or in-memory columnar area and do not want to use oracle tools, I found there are at least 2 ways.

  1. Run gcore on oracle process
  2. You can pipe to od or perl with 'shmcat'. Plus, you can dump shared memory segments selectively.

shmcat | Free Development software downloads at SourceForge.net

This is a simple tool that dumps shared memory segments (System V and POSIX), files and text. It might be useful when you have to debug programs that use shared memory.

Lastly, here are some caveats and foot notes.

  1. I don't think we(oracle) support that instance will run healthy after dumping SGA. Please check with apporopriate channel.
  2. I don't know if any oracle tool can dump SGA in similar way. And I'm afraid Oracle Support won't help finding such tool.
  3. I'm not sure if there's a case when one needs to dump SGA to salvage data even when db is noarchivelog mode and on-line redo logs are accidentally deleted or when all background processes died unexpectedly.
About

The views expressed on this blog are my own and do not necessarily reflect the views of Oracle.

Search

Archives
« April 2014
SunMonTueWedThuFriSat
  
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
   
       
Today