在CentOS7上部署GFS集群
准备工作
了解GFS的知识（一定要熟读！）
本文提到的GFS是Redhat的Global File System，不是Google的Google File System。GFS的官方文档链接如下：
RHEL6版（中文）https://access.redhat.com/documentation/zh-cn/red_hat_enterprise_linux/6/html/global_file_system_2/
RHEL7版（英文）https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/global_file_system_2/index
集群各主机hostname和hosts文件设置
在集群的每个主机上，修改hostname文件并确保主机名在集群中独一无二，在hosts文件中列出集群所有主机的hostname和IP地址。示例如下：
[root@a01 ~]# cat /etc/hostname
a01
[root@a01 ~]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.100.201 a01
192.168.100.202 a02
192.168.100.203 a03确保各主机已连接到SAN或IP-SAN
可参考我之前的一篇文章（但不要执行最后一步“在客户机上对ISCSI存储卷进行分区和挂载”，否则会遇到许多意料之外的问题）：
https://blog.csdn.net/huzhenwei/article/details/80690623
安装必要的软件包
yum -y install gfs2-utils lvm2-cluster
yum install lvm2-sysvinit配置corosync服务
新建/etc/corosync/corosync.conf文件，内容示例如下：
# Please read the corosync.conf.5 manual page
totem {
version: 2
cluster_name: cluster0
# crypto_cipher and crypto_hash: Used for mutual node authentication.
# If you choose to enable this, then do remember to create a shared
# secret with "corosync-keygen".
# enabling crypto_cipher, requires also enabling of crypto_hash.
crypto_cipher: none
crypto_hash: none
clear_node_high_bit: yes
# interface: define at least one interface to communicate
# over. If you define more than one interface stanza, you must
# also set rrp_mode.
interface {
# Rings must be consecutively numbered, starting at 0.
ringnumber: 0
# This is normally the *network* address of the
# interface to bind to. This ensures that you can use
# identical instances of this configuration file
# across all your cluster nodes, without having to
# modify this option.
bindnetaddr: 192.168.100.0
# However, if you have multiple physical network
# interfaces configured for the same subnet, then the
# network address alone is not sufficient to identify
# the interface Corosync should bind to. In that case,
# configure the *host* address of the interface
# instead:
# bindnetaddr: 192.168.1.1
# When selecting a multicast address, consider RFC
# 2365 (which, among other things, specifies that
# 239.255.x.x addresses are left to the discretion of
# the network administrator). Do not reuse multicast
# addresses across multiple Corosync clusters sharing
# the same network.
mcastaddr: 239.255.1.1
# Corosync uses the port you specify here for UDP
# messaging, and also the immediately preceding
# port. Thus if you set this to 5405, Corosync sends
# messages over UDP ports 5405 and 5404.
mcastport: 5405
# Time-to-live for cluster communication packets. The
# number of hops (routers) that this ring will allow
# itself to pass. Note that multicast routing must be
# specifically enabled on most network routers.
ttl: 1
}
}
logging {
# Log the source file and line where messages are being
# generated. When in doubt, leave off. Potentially useful for
# debugging.
fileline: off
# Log to standard error. When in doubt, set to no. Useful when
# running in the foreground (when invoking "corosync -f")
to_stderr: no
# Log to a log file. When set to "no", the "logfile" option
# must not be set.
to_logfile: yes
logfile: /var/log/cluster/corosync.log
# Log to the system log daemon. When in doubt, set to yes.
to_syslog: yes
# Log debug messages (very verbose). When in doubt, leave off.
debug: on
# Log messages with time stamps. When in doubt, set to on
# (unless you are only logging to syslog, where double
# timestamps can be annoying).
timestamp: on
logger_subsys {
subsys: QUORUM
debug: off
}
}
quorum {
# Enable and configure quorum subsystem (default: off)
# see also corosync.conf.5 and votequorum.5
provider: corosync_votequorum
expected_votes: 3
votes: 1
}
注意关键配置项：
cluster_name: 此项设置的集群名，在之后格式化逻辑卷为gfs2类型时要用到。
clear_node_high_bit: yes：dlm服务需要，否则无法启动。
quorum {}模块：集群选举投票设置，必需配置。如果是2节点的集群，可参考如下配置：
quorum {
# Enable and configure quorum subsystem (default: off)
# see also corosync.conf.5 and votequorum.5
provider: corosync_votequorum
two_node: 1
expected_votes: 2
#votes: 1
}
配置lvm
# 开启lvm的集群模式。
# 这个命令会自动修改/etc/lvm/lvm.conf配置文件中的locking_type和use_lvmetad选项的值
[root@a01 ~]# lvmconf --enable-cluster
修改后区别如下：
[root@a01 ~]# diff /etc/lvm/lvm.conf /etc/lvm/lvm.conf.lvmconfold
771c771
< locking_type = 3
---
> locking_type = 3
940c940
< use_lvmetad = 0
---
> use_lvmetad = 1启动相关服务
注意先后顺序，先在集群所有主机上启动corosync，集群状态正常之后，在各个主机上启动dlm、clvmd服务。
#在集群所有主机上启动corosync服务
systemctl enable corosync
systemctl start corosync在corosync服务启动完成后，可以使用corosync-quorumtool -s查看集群的状态，确保状态中的Quorate为Yes。示例如下：
[root@a01 ~]# corosync-quorumtool -s
Quorum information
------------------
Date: Fri Jun 15 16:56:07 2018
Quorum provider: corosync_votequorum
Nodes: 3
Node ID: 1084777673
Ring ID: 1084777673/380
Quorate: Yes在集群各个主机上启动dlm、clvmd服务
systemctl enable dlm
systemctl start dlm
systemctl enable clvmd
systemctl start clvmd设置集群卷组等并格式化gfs分区
在集群的一台主机上运行如下命令：
# 查看物理卷信息，如果没有列出存储服务器上的块设备，请确保各主机已连接到SAN或IP-SAN
pvscan
pvs
# 创建卷组、逻辑卷并将逻辑卷格式化为gfs2类型
vgcreate -Ay -cy gfsvg /dev/mapper/mpatha
lvcreate -L 800G -n gfsvol1 gfsvg
lvs -o +devices gfsvg
# 下面命令中的-j 4参数是指日志区的数量为4，这个数量通常为集群主机数N+1，
# 集群规模扩大时，可以使用gfs2_jadd命令添加日志区。
# -t后的“cluster0”为集群名，确保它与corosync.conf中配置的cluster_name一致。
mkfs.gfs2 -p lock_dlm -t cluster0:gfsvolfs -j 4 /dev/gfsvg/gfsvol1挂载gfs2逻辑卷
在集群的所有主机上运行如下命令：
# 创建挂载点目录
mkdir /mnt/iscsigfs
# 挂载gfs2分区
# 如果主机提示没有/dev/gfsvg/gfsvol1这个设备，原因是主机在创建此逻辑卷之前启动，将主机重新启动即可。
mount -t gfs2 /dev/gfsvg/gfsvol1 /mnt/iscsigfs -o noatime,nodiratime设置开机自动挂载，请参考：
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/storage_administration_guide/iscsi-api
常见错误
- 运行pvs、vgcreate等lvm相关命令时提示connect()等错误
错误示例如下，原因是clvmd没有正常启动
connect() failed on local socket: 没有那个文件或目录
Internal cluster locking initialisation failed.
WARNING: Falling back to local file-based locking.
Volume Groups with the clustered attribute will be inaccessible.
- 运行pvs、vgcreate等lvm相关命令时提示Skipping clustered volume group XXX或者Device XXX excluded by a filter
这通常是做了vgremove等操作后、或块设备上存在旧的卷组信息导致的，可以通过重新格式化块设备的方式解决。命令示例如下：
mkfs.xfs /dev/mapper/mpatha