High-Availability Storage with GlusterFS on CentOS 7 - Mirror across two storage servers

Transcription

1 High-Availability Storage with GlusterFS on CentOS 7 - Mirror across two storage servers This tutorial exists for these OS versions CentOS 6.3 CentOS 5.4 On this page 1 Preliminary Note 2 Enable additional Repositories 3 Setting up the GlusterFS Servers 4 Setting Up the GlusterFS Client 5 Testing 6 Links This tutorial shows how to set up a high-availability storage with two storage servers (CentOS 7.2) that use GlusterFS. Each storage server will be a mirror of the other storage server, and files will be replicated automatically across both storage servers. The client system (CentOS 7.2 as well) will be able to access the storage as if it was a local filesystem. GlusterFS is a clustered filesystem capable of scaling to several peta-bytes. It aggregates various storage bricks over Infiniband RDMA or TCP/IP interconnect into one large parallel network file system. Storage bricks can be made of any commodity hardware such as x86_64 servers with SATA-II RAID and Infiniband HBA. 1 Preliminary Note In this tutorial I use three systems, two servers, and a client: server1.example.com: IP address (server) server2.example.com: IP address (server) client1.example.com: IP address (client) All three systems should be able to resolve the other systems' hostnames. If this cannot be done through DNS, you should edit the /etc/hosts file so that it looks as follows on all three systems: nano /etc/hosts localhost localhost.localdomain localhost4 localhost4.localdomain server1.example.com server server2.example.com server client1.example.com client1 ::1 localhost localhost.localdomain localhost6 localhost6.localdomain6

2 (It is also possible to use IP addresses instead of hostnames in the following setup. If you prefer to use IP addresses, you don't have to care about whether the hostnames can be resolved or not.) 2 Enable additional Repositories server1.example.com/server2.example.com/client1.example.com: First, we import the GPG keys for software packages: rpm --import /etc/pki/rpm-gpg/rpm-gpg-key* Then we enable the EPEL 7 repository on our CentOS systems: yum -y install epel-release yum -y install yum-priorities Edit /etc/yum.repos.d/epel.repo... nano /etc/yum.repos.d/epel.repo... and add the line priority=10 to the [epel] section: [epel] name=extra Packages for Enterprise Linux 7 - $basearch #baseurl= mirrorlist= ch failovermethod=priority enabled=1 priority=10 gpgcheck=1 gpgkey=file:///etc/pki/rpm-gpg/rpm-gpg-key-epel-7 [...] Then we update our existing packages on the system: yum -y update 3 Setting up the GlusterFS Servers

3 server1.example.com/server2.example.com: GlusterFS is available in the repository of the CentOS storage special interest group. Install the repository with this command: yum -y install centos-release-gluster Then install the GlusterFS server as follows: yum -y install glusterfs-server Create the system startup links for the Gluster daemon and start it: systemctl enable glusterd.service systemctl start glusterd.service The command glusterfsd --version should now show the GlusterFS version that you've just installed ( in this case): glusterfsd --version glusterfs built on Jun :11:19 Repository revision: git://git.gluster.com/glusterfs.git Copyright (c) Red Hat, Inc. < GlusterFS comes with ABSOLUTELY NO WARRANTY. It is licensed to you under your choice of the GNU Lesser General Public License, version 3 or any later version (LGPLv3 or later), or the GNU General Public License, version 2 (GPLv2), in all cases as published by the Free Software Foundation. If you use a firewall, ensure that TCP ports 111, 24007, 24008, ( number of bricks across all volumes) are open onserver1.example.com and server2.example.com. Next, we must add server2.example.com to the trusted storage pool (please note that I'm running all GlusterFS configuration commands fromserver1.example.com, but you can as well run them from server2.example.com because the configuration is repliacted between the GlusterFS nodes - just make sure you use the correct hostnames or IP addresses): server1.example.com: On server1.example.com, run gluster peer probe server2.example.com gluster peer probe server2.example.com peer probe: success. The status of the trusted storage pool should now be similar to this: gluster peer status

4 gluster peer status Number of Peers: 1 Hostname: server2.example.com Uuid: 582e10da-aa1b-40b8-908c-213f16f57fe5 State: Peer in Cluster (Connected) Next, we create the share named testvol with two replicas (please note that the number of replicas is equal to the number of servers in this case because we want to set up mirroring) on server1.example.com and server2.example.com in the /data directory (this will be created if it doesn't exist): gluster volume create testvol replica 2 transport tcp server1.example.com:/data server2.example.com:/data force gluster volume create testvol replica 2 transport tcp server1.example.com:/data server2.example.com:/data force volume create: testvol: success: please start the volume to access data Start the volume: gluster volume start testvol The result should be: gluster volume start testvol volume start: testvol: success It is possible that the above command tells you that the action was not successful: gluster volume start testvol Starting volume testvol has been unsuccessful In this case, you should check the output of... server1.example.com/server2.example.com: netstat -tap grep glusterfsd on both servers. If you get output like this... netstat -tap grep glusterfsd tcp : :* LISTEN 22880/glusterfsd tcp 0 0 server1.example.c:49152 server2.example.c:49148 ESTABLISHED 22880/glusterfsd tcp 0 0 server1.example.c:49152 server1.example.c:49148 ESTABLISHED 22880/glusterfsd tcp 0 0 server1.example.c:49150 server1.example.c:24007 ESTABLISHED 22880/glusterfsd tcp 0 0 server1.example.c:49152 server2.example.c:49142 ESTABLISHED 22880/glusterfsd tcp 0 0 server1.example.c:49152 server1.example.c:49149 ESTABLISHED 22880/glusterfsd

5 ... everything is fine, but if you don't get any output... ~]# netstat -tap grep glusterfsd ~]#... restart the GlusterFS daemon on the corresponding server (server2.example.com in this case): server2.example.com: systemctl restart glusterd.service Then check the output of... netstat -tap grep glusterfsd... again on that server - it should now look like this: [root@server2 ~]# netstat -tap grep glusterfsd tcp : :* LISTEN 10971/glusterfsd tcp 0 0 server2.example.c:49152 server1.example.c:49140 ESTABLISHED 10971/glusterfsd tcp 0 0 server2.example.c:49152 server2.example.c:49149 ESTABLISHED 10971/glusterfsd tcp 0 0 server2.example.c:49152 server2.example.c:49143 ESTABLISHED 10971/glusterfsd tcp 0 0 server2.example.c:49152 server1.example.c:49142 ESTABLISHED 10971/glusterfsd tcp 0 0 server2.example.c:49150 server2.example.c:24007 ESTABLISHED 10971/glusterfsd [root@server2 ~]# Now back to server1.example.com: server1.example.com: You can check the status of the volume with the command gluster volume info gluster volume info Volume Name: testvol Type: Replicate Volume ID: e1f825ca-c9d9-4eeb-b6c5-d62c4aa02376 Status: Started Number of Bricks: 1 x 2 = 2 Transport-type: tcp Bricks: Brick1: server1.example.com:/data Brick2: server2.example.com:/data Options Reconfigured: performance.readdir-ahead: on By default, all clients can connect to the volume. If you want to grant access to client1.example.com (= ) only, run:

6 gluster volume set testvol auth.allow Please note that it is possible to use wildcards for the IP addresses (like *) and that you can specify multiple IP addresses separated by comma (e.g , ). The volume info should now show the updated status: gluster volume info gluster volume info Volume Name: testvol Type: Replicate Volume ID: e1f825ca-c9d9-4eeb-b6c5-d62c4aa02376 Status: Started Number of Bricks: 1 x 2 = 2 Transport-type: tcp Bricks: Brick1: server1.example.com:/data Brick2: server2.example.com:/data Options Reconfigured: auth.allow: performance.readdir-ahead: on 4 Setting Up the GlusterFS Client client1.example.com: On the client, we can install the GlusterFS client as follows: yum -y install glusterfs-client Then we create the following directory: mkdir /mnt/glusterfs That's it! Now we can mount the GlusterFS filesystem to /mnt/glusterfs with the following command: mount.glusterfs server1.example.com:/testvol /mnt/glusterfs (Instead of server1.example.com you can as well use server2.example.com in the above command!) You should now see the new share in the outputs of...

7 mount ~]# mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=930336k,nr_inodes=232584,mode=755) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,seclabel,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/s ystemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls) configfs on /sys/kernel/config type configfs (rw,relatime) /dev/mapper/centos-root on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota) selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=34,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) debugfs on /sys/kernel/debug type debugfs (rw,relatime) mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel) /dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota) tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,seclabel,size=188060k,mode=700)

8 server1.example.com:/testvol on /mnt/glusterfs type fuse.glusterfs (rw,relatime,user_id=0,group_id=0,default_permissions,allow_other,max_r ead=131072) fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) ~]#... and... df -h ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 28G 1.3G 27G 5% / devtmpfs 909M 0 909M 0% /dev tmpfs 919M 0 919M 0% /dev/shm tmpfs 919M 8.6M 910M 1% /run tmpfs 919M 0 919M 0% /sys/fs/cgroup /dev/sda1 497M 192M 306M 39% /boot tmpfs 184M 0 184M 0% /run/user/0 server1.example.com:/testvol 28G 12G 17G 41% /mnt/glusterfs [root@client1 ~]# Instead of mounting the GlusterFS share manually on the client, you add the mount command to /etc/rc.local file. I will not add it to /etc/fstab as rc.local is always executed after the network is up which is required for a network file system Open /etc/rc.local and append the following line: nano /etc/rc.local [...] /usr/sbin/mount.glusterfs server1.example.com:/testvol /mnt/glusterfs (Again, instead of server1.example.com you can as well use server2.example.com!) To test if your modified /etc/rc.local is working, reboot the client: reboot After the reboot, you should find the share in the outputs of... df -h... and... mount

9 5 Testing Now let's create some test files on the GlusterFS share: client1.example.com: touch /mnt/glusterfs/test1 touch /mnt/glusterfs/test2 Now let's check the /data directory on server1.example.com and server2.example.com. The test1 and test2 files should be present on each node: server1.example.com/server2.example.com: ls -l /data ls -l /data total 0 -rw-r--r--. 2 root root 0 Jul test1 -rw-r--r--. 2 root root 0 Jul test2 [root@server1 ~] Now we shut down server1.example.com and add/delete some files on the GlusterFS share on client1.example.com. server1.example.com: shutdown -h now client1.example.com: touch /mnt/glusterfs/test3 touch /mnt/glusterfs/test4 rm -f /mnt/glusterfs/test2 The commands may take some time to execute as the Glusterfs switches to server2 after he can not reach server1 anymore. We can see here the fault tolerance of the system as we can still work on our data storage share when server1 is offline. The changes should be visible in the /data directory onserver2.example.com: server2.example.com: ls -l /data [root@server2 ~]# ls -l /data total 8 -rw-r--r--. 2 root root 0 Jul 1 15:17 test1 -rw-r--r--. 2 root root 0 Jul 1 15:19 test3 -rw-r--r--. 2 root root 0 Jul 1 15:19 test4 Let's boot server1.example.com again and take a look at the /data directory: server1.example.com:

10 ls -l /data ls -l /data total 8 -rw-r--r--. 2 root root 0 Jul 1 15:17 test1 -rw-r--r--. 2 root root 0 Jul 1 15:19 test2 As you see, server1.example.com automatically synced the changed. In case that the change has not been synced yet, then this is easy to fix, all we need to do is invoke a read command on the GlusterFS share on client1.example.com, e.g.: client1.example.com: ls -l /mnt/glusterfs/ [root@client1 ~]# ls -l /data total 8 -rw-r--r--. 2 root root 0 Jul 1 15:17 test1 -rw-r--r--. 2 root root 0 Jul 1 15:19 test3 -rw-r--r--. 2 root root 0 Jul 1 15:19 test4 Now take a look at the /data directory on server1.example.com again, and you should see that the changes have been replicated to that node: server1.example.com: ls -l /data ls -l /data total 8 -rw-r--r--. 2 root root 0 Jul 1 15:17 test1 -rw-r--r--. 2 root root 0 Jul 1 15:19 test3 -rw-r--r--. 2 root root 0 Jul 1 15:19 test4 6 Links GlusterFS: GlusterFS 3.2 Documentation: tml/index.html CentOS: