OpenStack Cinder 与各种后端存储技术的集成叙述与实践
Cinder项目为管理快设备而生，它最重要的地方就是如何做到和各种存储后端就到完美适配，用好后端存储的功能，本文为Cinder 多种后端存储(LVM, FC+SAN, iSCSI+SAN, NFS, VMWARE, Glusterfs)的场景总结, 以防自己将来忘记，欢迎交流， 共同成长
1.LVM
开始OpenStack Cinder实践之旅的入门存储， cinder.conf 什么都不配，默认就是使用LVM， LVM的原理
先把分区用pvcreate做成物理卷， 再把多个物理卷做成一个卷组，然后创建volume的时候就通过lvcreate分配lvm逻辑卷。
做部署时，用dd在当前目录创建一个设定大小(本例中为10G)的文件（cinder-volumes），然后通过losetup命令把他影射为loop device（虚拟快设备），然后基于这个快设备建立逻辑卷， 然后就是建立vg， 建立vg的时候可以一次包含多个pv，本例只使用了一个。
dd if=/dev/zero of=/vol/cinder-volumes bs=1 count=0 seek=10G
# Mount the file.
loopdev=`losetup -f`
losetup $loopdev /vol/cinder-volumes
# Initialize as a physical volume.
pvcreate $loopdev
# Create the volume group.
vgcreate cinder-volumes $loopdev
# Verify the volume has been created correctly.
pvscan建立好volume group后，使用cinder.conf的初始配置即可, 注意多节点时要配置好iscsi_ip_address为提供存储服务节点的管理ip
重启cinder-volume服务
就可以进行正常的volume创建，挂载，卸载等等操作了
question1：LVM如何实现挂载？
创建很简单，通过lvcreate命令即可，挂载稍微复杂点， 先要把卷export为scsi存储目标设备(target，会有个lun ID), 然后通过linux scsi initiator软件实现到目标设备的连接，这里用到两个软件，scsi tagert管理软件(这个里面有多种如Tgt，Lio，Iet，ISERTgt，默认使用Tgt， 都是为装有SCSI initiator的操作系统提供块级scsi存储)与linux scsi initiator，所以两次操作分别对应命令为tgtadm与iscsiadm。
2. FC(Fibre Channel) +SAN 设备
要求：
a) 计算节点所在的机器一定要有HBA卡(光纤网卡)，
查看host上有无HBA卡方式：
一种方法：
$ lspci
20:00.0 Fibre Channel: Emulex Corporation Zephyr-X LightPulse Fibre Channel Host Adapter (rev 02)
20:00.1 Fibre Channel: Emulex Corporation Zephyr-X LightPulse Fibre Channel Host Adapter (rev 02可以查看/sys/class/fc_host/
当有两块光纤网卡，则有host1 与host2两个目录$ cat /sys/class/fc_host/host1/port_name
0x10000090fa1b825a wwpn (作用如同MAC地址)ww_2145:SVC:superuser>svcinfo lsfabric -delim ! -wwpn "10000090fa1b825a"
10000090FA1B825A!0A0C00!3!node_165008!500507680130DBEA!2!0A0500!active!x3560m4-06MFZF1!!Host下面是实践，以Storwize设备为例：
volume_driver = cinder.volume.drivers.storwize_svc.StorwizeSVCDriver
san_ip = 10.2.2.123
san_login = superuser
#san_password = passw0rd
san_private_key = /svc_rsa
storwize_svc_volpool_name = DS3524_DiskArray1
storwize_svc_connection_protocol = FCsan_password 与san_private_key可以二选一，推荐san_private_key 方式，这个私钥文件用ssh-keygen生成，生成好留下私钥， 把公钥放到san设备上，以后其他host也想连接此存储设备时， 可直接使用此私钥， 不需重复生成。
测试过程，建个volume
[root@localhost ~]# cinder create --display-name test55 1
[root@localhost ~]# nova volume-list
+--------------------------------------+-----------+--------------+------+-------------+-------------+
| ID | Status | Display Name | Size | Volume Type | Attached to |
+--------------------------------------+-----------+--------------+------+-------------+-------------+
| 24f7e457-f71a-43ce-9ca6-4454fbcfa31f | available | test55 | 1 | None | |
+--------------------------------------+-----------+--------------+------+-------------+-------------+[root@localhost ~]# nova list
+--------------------------------------+-----------+--------------+------+-------------+-------------+
| 77d7293f-7a20-4f36-ac86-95f4c24b29ae | test2 | ACTIVE | - | Running | net_local=10.0.1.5 |
+--------------------------------------+-------+--------+------------+-------------+--------------------+
[root@localhost ~]# nova volume-attach 77d7293f-7a20-4f36-ac86-95f4c24b29ae 24f7e457-f71a-43ce-9ca6-4454fbcfa31f
+----------+--------------------------------------+
| Property | Value |
+----------+--------------------------------------+
| device | /dev/vdb |
| id | 24f7e457-f71a-43ce-9ca6-4454fbcfa31f |
| serverId | 77d7293f-7a20-4f36-ac86-95f4c24b29ae |
| volumeId | 24f7e457-f71a-43ce-9ca6-4454fbcfa31f |
+----------+--------------------------------------+
[root@localhost ~]# cinder list
+--------------------------------------+-----------+--------------+------+-------------+----------+--------------------------------------+
| ID | Status | Display Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+-----------+--------------+------+-------------+----------+--------------------------------------+
| 24f7e457-f71a-43ce-9ca6-4454fbcfa31f | in-use | test55 | 1 | None | false | 77d7293f-7a20-4f36-ac86-95f4c24b29ae |
+--------------------------------------+-----------+--------------+------+-------------+-------------+3. iSCSI+SAN 设备
这个是通过TCP/IP 协议来连接存储设备的，只需要保证存储服务节点能够ping通san ip和计算机点能ping存储设备上的iSCSI node ip即可。
以ibm的svc或者v7000为例。与FC部分配置唯一的不同就是
storwize_svc_connection_protocol = FC ==》 storwize_svc_connection_protocol = iSCSI4. 使用VMWARE
这个主要是使用vcenter来管理快存储。cinder这个其实就是封装了一层， 最终都是调用vcenter的存储管理的功能。就像是一个中转一样，修改cinder.conf中如下配置项
volume_driver = cinder.volume.drivers.vmware.vmdk.VMwareVcVmdkDriver
vmware_host_ip = $VCENTER_HOST_IP
vmware_host_username = $VCENTER_HOST_USERNAME
vmware_host_password = $VCENTER_HOST_PASSWORD
vmware_wsdl_location = $WSDL_LOCATION
# VIM Service WSDL Location
# example, 'file:///home/SDK5.5/SDK/vsphere-ws/wsdl/vim25/vimService.wsdl测试过程同2，一切即ok。
5.NFS
非常普遍的一种网络文件系统，原理可google，直接开始cinder中的实践
第一步： 规划好NFS存储server端， 分别分布在那些节点，那些目录，这里在两个节点做规划，作为nfs server端，10.11.0.16:/var/volume_share和10.11.1.178:/var/volume_share，在这两台机器上建好目录/var/volume_share， 并export为nfs存储，在两个节点上启动nfs服务
第二步：建立/etc/cinder/share.txt，内容如下， 告知可以被mount的共享存储
10.11.0.16:/var/volume_share
10.11.1.178:/var/volume_share$ chmod 0640 /etc/cinder/share.txt
$ chown root:cinder /etc/cinder/share.txtvolume_driver=cinder.volume.drivers.nfs.NfsDriver
nfs_shares_config=/etc/cinder/shares.txt
nfs_mount_point_base=$state_path/mnt有一次变更环境，voluem-attach报了错：
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher connector)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/nova/openstack/common/excutils.py", line 68, in __exit__
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher six.reraise(self.type_, self.value, self.tb)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/nova/virt/block_device.py", line 239, in attach
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher device_type=self['device_type'], encryption=encryption)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/nova/virt/libvirt/driver.py", line 1263, in attach_volume
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher disk_dev)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/nova/openstack/common/excutils.py", line 68, in __exit__
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher six.reraise(self.type_, self.value, self.tb)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/nova/virt/libvirt/driver.py", line 1250, in attach_volume
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher virt_dom.attachDeviceFlags(conf.to_xml(), flags)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 179, in doit
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher result = proxy_call(self._autowrap, f, *args, **kwargs)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 139, in proxy_call
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher rv = execute(f,*args,**kwargs)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib/python2.6/site-packages/eventlet/tpool.py", line 77, in tworker
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher rv = meth(*args,**kwargs)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher File "/usr/lib64/python2.6/site-packages/libvirt.py", line 419, in attachDeviceFlags
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher if ret == -1: raise libvirtError ('virDomainAttachDeviceFlags() failed', dom=self)
2014-06-12 11:41:58.659 19312 TRACE oslo.messaging.rpc.dispatcher libvirtError: internal error unable to execute QEMU command '__com.redhat_drive_add': Device 'drive-virtio-disk1' could not be initialized这个错来自libvirt，做以下设置即可，先察看virt_use_nfs是off还是on
$ /usr/sbin/getsebool virt_use_nfs$ /usr/sbin/setsebool -P virt_use_nfs on6.GlusterFS
写这么多， 觉得这个是比较好的，难怪redhat会收购它， 有眼光啊，它为分布式文件系统，可扩展到几个PB数量级的集群文件系统。可以把多个不同类型的存储块通过Infiniband RDMA或者TCP/IP汇聚成一个大的并行网络文件系统。
简单总结自己体会到的它的两个特性1.横向扩展能力强， 可以把不同节点的brick server组合起来，形成大的并行网络文件系统
2.可以做软RAID，通过条带技术[stripe] 和镜像卷[replica], 提高并发读写速度和容灾能力
下面提供一个cinder+glusterfs实践全过程， 穿插叙述glusterfs的优良特性的说明和使用
第一步：首先安装部署好gluterfs server环境：
本例中使用10.11.0.16和10.11.1.178作为连个节点，首先要在它们上装包
两种方式：yum源 or RPM 包
1：yum -y install glusterfs glusterfs-fuse glusterfs-server2：去以下网址下载包， 例如http://download.gluster.org/pub/gluster/glusterfs/3.5/3.5.0/RHEL/epel-6.5/x86_64/
glusterfs-3.5.0-2.el6.x86_64.rpm glusterfs-fuse-3.5.0-2.el6.x86_64.rpm glusterfs-server-3.5.0-2.el6.x86_64.rpm
glusterfs-cli-3.5.0-2.el6.x86_64.rpm glusterfs-libs-3.5.0-2.el6.x86_64.rpm
我下载了3.5版本的，利用rpm的方式安装上。
装好之后，规划好多节点上的brick server，本例中将在10.11.1.178 和10.11.0.16上分别建立/var/data_cinder和/var/data_cinder2目录，并在10.11.1.178上建立存储集群cfs。
1.启动10.11.1.178和10.11.0.16上的glusterd服务
[root@chen ~]# /etc/init.d/glusterd start
[root@kvm-10-11-1-178 ~]# gluster peer probe 10.11.0.16
[root@kvm-10-11-1-178 ~]# gluster peer probe 10.11.1.178 #本地也可以不执行用法：$ gluster volume create
stripe 条带，类似做RAID0， 提高读写性能的，
replica 顾名思义，镜像，类似于做RAID1， 数据会成镜像的写
stripe+ replica 可以做RAID10，此时stripe COUNT * replica COUNT =brick-server COUNT， 说多了，哈哈
[root@kvm-10-11-0-16 var]# mkdir data_cinder
[root@kvm-10-11-0-16 var]# mkdir data_cinder2
[root@kvm-10-11-1-178 var]# mkdir data_cinder
[root@kvm-10-11-1-178 var]# mkdir data_cinder2
[root@kvm-10-11-1-178 var]# gluster volume create cfs stripe 2 replica 2 10.11.0.16:/var/data_cinder2 10.11.1.178:/var/data_cinder 10.11.0.16:/var/data_cinder 10.11.1.178:/var/data_cinder2 force
volume create: cfs: success: please start the volume to access data注意：不要 gluster volume create cfs stripe 2 replica 2 10.11.0.16:/var/data_cinder2 10.11.0.16:/var/data_cinder 10.11.1.178:/var/data_cinder 10.11.1.178:/var/data_cinder2 force， 因为前两个是做RAID1， 在同一个节点上就起不到容灾能力了。
4. start 存储集群用法：$ gluster volume start
[root@kvm-10-11-1-178 var]# gluster volume start cfs
volume start: cfs: success
[root@kvm-10-11-1-178 ~]# gluster volume info all
Volume Name: cfs
Type: Striped-Replicate
Volume ID: ac614af9-11b8-4ff3-98e6-fe8c3a2568b6
Status: Started
Number of Bricks: 1 x 2 x 2 = 4
Transport-type: tcp
Bricks:
Brick1: 10.11.0.16:/var/data_cinder2
Brick2: 10.11.1.178:/var/data_cinder
Brick3: 10.11.0.16:/var/data_cinder
Brick4: 10.11.1.178:/var/data_cinder2 第二步：client端，也就是cinder-volume service所在的节点，这端除了glusterfs-server包不用装，其他都要装上，这端就和nfs那些一样了，保证服务启动时会做好mount。
建立/etc/cinder/share.conf，内容如下， 告知可以被mount的集群存储
10.11.1.178:/cfs$ chmod 0640 /etc/cinder/share.conf
$ chown root:cinder /etc/cinder/share.confglusterfs_shares_config = /etc/cinder/shares.conf
glusterfs_mount_point_base = /var/lib/cinder/volumes
volume_driver=cinder.volume.drivers.glusterfs.GlusterfsDriver[root@chen ~]# for i in api scheduler volume; do sudo service openstack-cinder-${i} restart; done[root@chen ~]# cinder create --display-name chenxiao-glusterfs 1
[root@chen ~]# cinder list
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+
| ID | Status | Display Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+
| 866f7084-c624-4c11-a592-8c00fcabfb23 | available | chenxiao-glusterfs | 1 | None | false | |
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+
[root@kvm-10-11-1-178 data_cinder]# ls -al
总用量 20
drwxrwxr-x 3 root cinder 4096 6月 18 20:43 .
drwxr-xr-x. 27 root root 4096 6月 18 10:24 ..
drw------- 240 root root 4096 6月 18 20:39 .glusterfs
-rw-rw-rw- 2 root root 536870912 6月 18 20:39 volume-866f7084-c624-4c11-a592-8c00fcabfb23[root@chen data_cinder]# nova volume-attach f5b7527e-2ab8-424c-9842-653bd73e8f26 866f7084-c624-4c11-a592-8c00fcabfb23
+----------+--------------------------------------+
| Property | Value |
+----------+--------------------------------------+
| device | /dev/vdd |
| id | 866f7084-c624-4c11-a592-8c00fcabfb23 |
| serverId | f5b7527e-2ab8-424c-9842-653bd73e8f26 |
| volumeId | 866f7084-c624-4c11-a592-8c00fcabfb23 |
+----------+--------------------------------------+[root@chen data_cinder]# cinder list
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+
| ID | Status | Display Name | Size | Volume Type | Bootable | Attached to |
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+
| 866f7084-c624-4c11-a592-8c00fcabfb23 | in-use | chenxiao-glusterfs | 1 | None | false | f5b7527e-2ab8-424c-9842-653bd73e8f26 |
+--------------------------------------+----------------+--------------------+------+-------------+----------+--------------------------------------+