Kronos

主要是把XCP toolstack安裝到已經現有的OS環境裏頭


http://wiki.xen.org/wiki/Project_Kronos

Citrix Xenserver VDI type

Type:	enum vdi_type
	Value Description system a disk that may be replaced on upgrade user a disk that is always preserved on upgrade ephemeral a disk that may be reformatted on upgrade suspend a disk that stores a suspend image crashdump a disk that stores VM crashdump information
Name:	type
	type of the VDI

Field is read-only



http://docs.vmd.citrix.com/XenServer/4.0.1/api/docs/html/browser.html

Xenstore

Referenece:
1. Xenstore入門, http://blog.csdn.net/xulai1001/article/details/7070800

Xen / XCP / Xenserver comparison

http://wiki.xen.org/wiki/Xen_/_XCP_/_XCP_on_Linux_Overview

xapi a.k.a XenAPI

XAPI is at the heart of XenServer. It manages everything – all the resources in your XenServer environment, 

1. reads in configs, 
2. initializes networking paths, 
3. checks licensing, 
4. maintains a Database with all this info (the XAPI database), 
5. manages Storage Repositories, 
6. manages VMs, 
7. tracks VM states, 
8. manages networking, 
9. High Availability 
10. other XenServer hosts in the pool and more……

Each XenServer request or action is done via Xapi – and only by asking the Master XenServer XAPI to do so. 

A copy of the XAPI database (or you could consider this to be the state of XAPI) is synchronized among all the hosts in the pool – so they all have a copy of the current XAPI database – giving them the knowledge of what is going on – and in the case of the master going down – a new master can be appointed from the pool using the XAPI state information or shared database.

When you collect a status report from XenServer – the XAPI Database is stored in the status report. It is a relational database – and shows us the state of the environment at that point in time (when the status report was captured).

Reference

1. http://xenme.com/688

2. XAPI Developer Guide, http://wiki.xensource.com/xenwiki/XAPI_Developer_Guide

3. http://blogs.citrix.com/2011/05/18/so-what-is-xenserver-xapi/

Xen / XCP / Xenserver in OpenStack Installation

Post install steps

You are now ready to install OpenStack onto your XenServer system. This process involves the following steps:

• For resize and migrate functionality, please perform the changes described in the Configuring Resize section of the OpenStack Compute Administration Manual.
• Install the VIF isolation rules to help prevent mac and ip address spoofing.
• Install the XenAPI plugins - see the next section.
• In order to support AMI type images, you need to set up /boot/guest symlink/directory in Dom0. For detailed instructions, see next section.
• To support resize/migration, set up an ssh trust relation between your XenServer hosts, and ensure /images is properly set up. See next section for more details.
• Create a Paravirtualised virtual machine that can run the OpenStack compute code.
• Install and configure the nova-compute in the above virtual machine.

Ensure you are using the EXT type of storage repository (SR). Features that require access to VHD files (such as copy on write, snapshot and migration) do not work when using the LVM SR. Storage repository (SR) is a XenAPI specific term relating to the physical storage on which virtual disks are stored.

On the XenServer/XCP installation screen, this is selected by choosing "XenDesktop Optimized" option. In case you are using an answer file, make sure you use srtype="ext" within the installation tag of the answer file.

In order to support AMI type images, you need to set up /boot/guest symlink/directory in Dom0.

Prepare for AMI Type Images

    為了讓Xenserver的dom0能夠支援Amazon的VM Image type: AMI，所以必須在dom0建立/boot/guest的資料夾，讓OpenStack能夠從解壓縮開的AMI以及ARI Image中放kernel以及ramdisk到這個資料夾。正常來說這個資料夾是由OpenStack來進行維護的，不會因為power failures 或者意外事故造成一些垃圾檔案充斥在dom0中，所以推薦的作法是做symbolic link。

In order to support AMI type images within your OpenStack installation, a directory /boot/guest needs to be created inside Dom0. The OpenStack VM will put the kernel and ramdisk extracted from the AKI and ARI images to this location.

This directory's content will be maintained by OpenStack, and its size should not increase during normal operation, however in case of power failures or accidental shutdowns, some files might be left over. In order to prevent these files to fill up Dom0's disk, it is recommended to set up this directory as a symlink pointing to a subdirectory of the local SR.

Execute the following commands in Dom0 to achieve the above mentioned setup:

# LOCAL_SR=$(xe sr-list name-label="Local storage" --minimal)
# LOCALPATH="/var/run/sr-mount/$LOCAL_SR/os-guest-kernels"
# mkdir -p "$LOCALPATH"
# ln -s "$LOCALPATH" /boot/guest