XCP / Citrix Xenserver Volume Drivers on OpenStack

PS: Cinder是由Folsom版本開始從原本的nova-volume這部分去進行抽離的子專案

XenAPINFS

XenAPINFS is a Block Storage (Cinder) driver which is using an NFS share through XenAPI's Storage Manager to store virtual disk images and exposing those virtual disks as volumes.

XenAPINFS不能直接存取NFS，只能透過XenAPI Storage Manager來存取NFS。
( This driver is not accessing the NFS share directly, it is only accessing the share through XenAPI Storage Manager. )

This driver should be considered as a reference implementation for using XenAPI's storage manager in OpenStack ( present in XenServer and XCP).

配置方式

1. Local:
   推薦的做法，這樣的話可以使用qemu-img，但必須在當作Storage Controller上的XCP/Xenserver host上開啟一台PV guest VM安裝 cinder + XenAPINFS driver
2. Remote:
   不需要使用PV guest VM，直接拿XCP/Xenserver當作Storage Controller。但這樣的話只能用VDI格式的VHD。

Source Code:

1. Grizzly cinder, https://github.com/openstack/cinder/blob/stable/grizzly/cinder/volume/drivers/xenapi/sm.py

XenAPI Storage Manager Volume Driver ( only in Folsom version, 在grizzly版中似乎已經移除 )

The Xen Storage Manager Volume driver (xensm) is a XenAPI hypervisor specific volume driver

Source Code:

nova,
https://github.com/openstack/nova/blob/stable/folsom/nova/volume/xensm.py
cinder,
https://github.com/openstack/cinder/blob/stable/folsom/cinder/volume/xensm.py

功用:

1. provide basic storage functionality, including volume creation and destruction, on a number of different storage back-ends.
2. It also enables the capability of using more sophisticated storage back-ends for operations like cloning/snapshots, etc.

The list below shows some of the storage plugins already supported in Citrix XenServer and Xen Cloud Platform (XCP):

1. NFS VHD: 
   Storage repository (SR) plugin which stores disks as Virtual Hard Disk (VHD) files on a remote Network File System (NFS).
   
   
2. Local VHD on LVM: 
   SR plugin which represents disks as VHD disks on Logical Volumes (LVM) within a locally-attached Volume Group.
   
   
3. HBA LUN-per-VDI driver: 
   SR plugin which represents Logical Units (LUs) as Virtual Disk Images (VDIs) sourced by host bus adapters (HBAs). E.g. hardware-based iSCSI or FC support.
   
   
4. NetApp: 
   SR driver for mapping of LUNs to VDIs on a NETAPP server, providing use of fast snapshot and clone features on the filer.
   
   
5. LVHD over FC: 
   SR plugin which represents disks as VHDs on Logical Volumes within a Volume Group created on an HBA LUN. E.g. hardware-based iSCSI or FC support.
   
   
6. iSCSI: 
   Base ISCSI SR driver, provides a LUN-per-VDI. Does not support creation of VDIs but accesses existing LUNs on a target.
   
   
7. LVHD over iSCSI: 
   SR plugin which represents disks as Logical Volumes within a Volume Group created on an iSCSI LUN.
   
   
8. EqualLogic: 
   SR driver for mapping of LUNs to VDIs on a EQUALLOGIC array group, providing use of fast snapshot and clone features on the array.