对于一个存储，不可避免的会遇到扩容、缩减存储容量的问题。
1 为Glusterfs扩容
提前准备好了一个gluster volume:
[root@node01 ~]# gluster volume info repvol Volume Name: repvol Type: Replicate Volume ID: 7015b7fe-8039-4d5d-b698-e8321df5289c Status: Started Snapshot Count: 0 Number of Bricks: 1 x 2 = 2 Transport-type: tcp Bricks: Brick1: node01.lab.example.com:/bricks/thinvol1/brick Brick2: node02.lab.example.com:/bricks/thinvol1/brick Options Reconfigured: performance.stat-prefetch: off storage.batch-fsync-delay-usec: 0 server.allow-insecure: on performance.readdir-ahead: on transport.address-family: inet nfs.disable: on
可以看出repvol是一个包含2个brick的1x2复制卷，将repvol挂载到node02 server上，并写入一些数据以作测试。
[root@node02 ~]# mount -t cifs //node01.lab.example.com/gluster-repvol -o user=smbuser,pass=redhat /mnt
[root@node02 ~]# cd /mnt
[root@node02 mnt]# ls
[root@node02 mnt]# touch {1..100}.file使用如下命令为repvol再增加两个brick
[root@node01 ~]# gluster volume add-brick repvol node01.lab.example.com:/bricks/thinvol2/brick node02.lab.example.com:/bricks/thinvol2/brick volume add-brick: success
[root@node01 ~]# gluster volume info repvol Volume Name: repvol Type: Distributed-Replicate Volume ID: 7015b7fe-8039-4d5d-b698-e8321df5289c Status: Started Snapshot Count: 0 Number of Bricks: 2 x 2 = 4 Transport-type: tcp Bricks: Brick1: node01.lab.example.com:/bricks/thinvol1/brick Brick2: node02.lab.example.com:/bricks/thinvol1/brick Brick3: node01.lab.example.com:/bricks/thinvol2/brick Brick4: node02.lab.example.com:/bricks/thinvol2/brick Options Reconfigured: performance.stat-prefetch: off storage.batch-fsync-delay-usec: 0 server.allow-insecure: on performance.readdir-ahead: on transport.address-family: inet nfs.disable: on
可以看到repvol已经变成了一个2x2的分布式复制卷，扩容后我们还需要把原有的数据rebalance
[root@node01 ~]# gluster volume rebalance repvol start volume rebalance: repvol: success: Rebalance on repvol has been started successfully. Use rebalance status command to check status of the rebalance process. ID: a8fba779-6c2d-449b-8847-58aeb2ae1798
[root@node01 ~]# gluster volume rebalance repvol status Node Rebalanced-files size scanned failures skipped status run time in h:m:s --------- ----------- ----------- ----------- ----------- ----------- ------------ -------------- localhost 48 0Bytes 100 0 0 completed 0:0:5 node02 0 0Bytes 0 0 0 completed 0:0:2 volume rebalance: repvol: success
这里有一个需要注意的地方，当数据量太大的时候，对数据进行rebalance必须要考虑的一个问题就是性能，不能因为数据rebalance而影响我们的存储的正常使用。Glusterfs也考虑到了这个问题，在进行数据rebalance时，根据实际场景不同设计了三种不同的“级别”：
1）lazy：每次仅可以迁移一个文件
2）normal:默认设置，每次迁移2个文件或者是(CPU逻辑个数-4)/2,哪个大，选哪个
3）aggressive:每次迁移4个文件或者是(CPU逻辑个数-4)/2
通过以下命令进行配置：
gluster volume set VOLUME-NAME cluster.rebal-throttle [lazy|normal|aggressive]
如将volume repvol设置为lazy
[root@node01 ~]# gluster volume set repvol cluster.rebal-throttle lazy volume set: success
2 缩减volume大小
将我们刚刚添加的2个brick再从volume repovl中删掉
[root@node01 ~]# gluster volume remove-brick repvol node01.lab.example.com:/bricks/thinvol2/brick node02.lab.example.com:/bricks/thinvol2/brick start volume remove-brick start: success ID: db72aaf8-e60d-4e56-be60-54469df9c233
[root@node01 ~]# gluster volume remove-brick repvol node01.lab.example.com:/bricks/thinvol2/brick node02.lab.example.com:/bricks/thinvol2/brick status Node Rebalanced-files size scanned failures skipped status run time in h:m:s --------- ----------- ----------- ----------- ----------- ----------- ------------ -------------- localhost 48 0Bytes 101 0 0 completed 0:0:3 node02 0 0Bytes 0 0 0 completed 0:0:1
[root@node01 ~]# gluster volume remove-brick repvol node01.lab.example.com:/bricks/thinvol2/brick node02.lab.example.com:/bricks/thinvol2/brick commit Removing brick(s) can result in data loss. Do you want to Continue? (y/n) y volume remove-brick commit: success Check the removed bricks to ensure all files are migrated. If files with data are found on the brick path, copy them via a gluster mount point before re-purposing the removed brick.
此时再看repvol已经重新变为1x2的复制卷了
[root@node01 ~]# gluster volume info repvol Volume Name: repvol Type: Replicate Volume ID: 7015b7fe-8039-4d5d-b698-e8321df5289c Status: Started Snapshot Count: 0 Number of Bricks: 1 x 2 = 2 Transport-type: tcp Bricks: Brick1: node01.lab.example.com:/bricks/thinvol1/brick Brick2: node02.lab.example.com:/bricks/thinvol1/brick Options Reconfigured: cluster.rebal-throttle: lazy performance.stat-prefetch: off storage.batch-fsync-delay-usec: 0 server.allow-insecure: on performance.readdir-ahead: on transport.address-family: inet nfs.disable: on
[root@node01 ~]# ls /bricks/thinvol1/brick/ | wc -w 100
本文出自 “不积跬步，无以至千里” 博客，请务必保留此出处http://jiaxiaolei.blog.51cto.com/3117381/1951535
原文地址：http://jiaxiaolei.blog.51cto.com/3117381/1951535
