RH236扩缩容volumes–缩容volume
本章节介绍如何对GlusterFS进行缩容volumes。
RHCA专栏地址：https://blog.csdn.net/qq_41765918/category_11532281.html
缩容volume
途径：将brick从volume中剔除，实现缩容
注意：
剔除的brick个数，要考虑剔除之后，数据会不会丢，移除Replicate类型的brick数据不会丢失。
1） 移除Replicate类型的brick
需要指明移除后replica的数量，并且直接使用force指令直接执行。
# gluster volume remove-brick vol1 replica 1 \
node1:/brick/brick1/brick \
force
可能出现的报错：
volume remove-brick start: failed: Remove exactly 1 brick(s) from each subvolume.
出现这个报错主要是由于删除带有Replicate类型的复合卷时，命令内指明删除的brick存在有相同的Replicate的brick。
解决办法：相同的Replicate brick具有相同的trusted.glusterfs.dht目录扩展属性，
通过查看trusted.glusterfs.dht来修改需要剔除的目录。
# getfattr -d -m ".*" /brick/brick1/brick1
getfattr: Removing leading '/' from absolute path names
# file: brick/brick1/brick1
security.selinux="system_u:object_r:unlabeled_t:s0"
trusted.gfid=0sAAAAAAAAAAAAAAAAAAAAAQ==
trusted.glusterfs.dht=0sAAAAAQAAAAB//w==
trusted.glusterfs.dht.commithash="3634901324"
trusted.glusterfs.volume-id=0sf1W8jgybTceZGk4fsq4eew==
2）移除非Replicate类型的volume
# gluster volume remove-brick vol1 replica 1 \
node1:/brick/brick1/brick \
start
#这种方式，不会改变原有类型，但可能会丢失数据
查看移除状态：
# gluster volume remove-brick vol1 node1:/brick/brick1/brick status
移除完成之后，要进行提交操作
# gluster volume remove-brick vol1 node1:/brick/brick1/brick commit
移除操作的场景：
当有服务器down的时候，为了保证glusterfs工作正常，需要将多余server移除
课本练习
[root@workstation ~]# lab shrinkvolume setup
Setting up servers for lab exercise work:
• Testing if all hosts are reachable.......................... SUCCESS
• Adding glusterfs to runtime firewall on servera............. SUCCESS
• Adding glusterfs to permanent firewall on servera........... SUCCESS
• Adding glusterfs to runtime firewall on serverb............. SUCCESS
• Adding glusterfs to permanent firewall on serverb........... SUCCESS
• Adding glusterfs to runtime firewall on serverc............. SUCCESS
• Adding glusterfs to permanent firewall on serverc........... SUCCESS
• Adding glusterfs to runtime firewall on serverd............. SUCCESS
• Adding glusterfs to permanent firewall on serverd........... SUCCESS
• Adding servera to trusted storage pool...................... SUCCESS
…………
1. 在您的servera系统上，检查shrinkme卷的布局，并确定可以删除哪两个块。
[root@servera ~]# gluster volume info shrinkme
Volume Name: shrinkme
Type: Distributed-Replicate
Volume ID: ea91e5b1-b57b-4d72-a5e9-2c8c3d94677d
Status: Started
Number of Bricks: 2 x 2 = 4
Transport-type: tcp
Bricks:
Brick1: servera:/bricks/brick-a2/brick
Brick2: serverb:/bricks/brick-b2/brick
Brick3: serverc:/bricks/brick-c2/brick
Brick4: serverd:/bricks/brick-d2/brick
Options Reconfigured:
performance.readdir-ahead: on
2. 缩容brick-c2和brick-d2
[root@servera ~]# gluster volume remove-brick shrinkme serverc:/bricks/brick-c2/brick serverd:/bricks/brick-d2/brick start
volume remove-brick start: success
ID: 667f7585-a9c4-43e8-8f3b-0482bfb19d97
[root@servera ~]# gluster volume remove-brick shrinkme serverc:/bricks/brick-c2/brick serverd:/bricks/brick-d2/brick status
Node Rebalanced-files size scanned failures skipped status run time in secs
--------- ----------- ----------- ----------- ----------- ----------- ------------ --------------
serverc.lab.example.com 7 0Bytes 7 0 0 completed 1.00
serverd.lab.example.com 0 0Bytes 0 0 0 completed 0.00
[root@servera ~]# gluster volume remove-brick shrinkme serverc:/bricks/brick-c2/brick serverd:/bricks/brick-d2/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.
3. 脚本评分
[root@workstation ~]# lab shrinkvolume grade
rebalance总结
值得注意的是，在扩容GlusterFS后，需要手动执行gluster rebalance命令来触发数据均衡功能。扩容后会带来新旧节点数据不均衡的问题，进一步发展可能会导致旧节点负载过高而出现性能问题，甚至最终影响到数据可靠性和可用性，因此，扩容后进行数据均衡是非常必要的。
而在缩容GlusterFS后，并不需要手动执行命令，缩容时会自动触发执行数据均衡过程，这是因为如果缩容时没有自动进行数据均衡，那么被剔除掉的节点或子卷上的数据将不再可用，从而会导致数据的丢失，这对于用户来说是不可接受的，因此数据均衡在缩容时是不可或缺的，程序实现采用自动触发方式也就理所当然了。
章节实验
[root@workstation ~]# lab extendvolume-lab setup
Setting up servers for lab exercise work:
• Testing if all hosts are reachable.......................... SUCCESS
• Adding glusterfs to runtime firewall on servera............. SUCCESS
• Adding glusterfs to permanent firewall on servera........... SUCCESS
• Adding glusterfs to runtime firewall on serverb............. SUCCESS
• Adding glusterfs to permanent firewall on serverb........... SUCCESS
• Adding glusterfs to runtime firewall on serverc............. SUCCESS
• Adding glusterfs to permanent firewall on serverc........... SUCCESS
• Adding glusterfs to runtime firewall on serverd............. SUCCESS
• Adding glusterfs to permanent firewall on serverd........... SUCCESS
• Adding servera to trusted storage pool...................... SUCCESS
…………
1. 按要求进行扩容。
[root@servera ~]# gluster volume info important
Volume Name: important
Type: Distribute
Volume ID: b4500b45-891c-41ea-b198-3b9467b9f197
Status: Started
Number of Bricks: 2
Transport-type: tcp
Bricks:
Brick1: servera:/bricks/brick-a3/brick
Brick2: serverb:/bricks/brick-b3/brick
Options Reconfigured:
performance.readdir-ahead: on
[root@servera ~]# gluster volume add-brick important replica 2 serverc:/bricks/brick-c3/brick serverd:/bricks/brick-d3/brick
volume add-brick: success
[root@servera ~]# gluster volume rebalance important start
volume rebalance: important: success: Rebalance on important has been started successfully. Use rebalance status command to check status of the rebalance process.
ID: b1f99fb3-3155-430a-b30e-f6ed3e73d603
[root@servera ~]# gluster volume rebalance important status
Node Rebalanced-files size scanned failures skipped status run time in secs
--------- ----------- ----------- ----------- ----------- ----------- ------------ --------------
localhost 0 0Bytes 49 0 0 completed 1.00
serverb.lab.example.com 0 0Bytes 51 0 0 completed 1.00
serverc.lab.example.com 0 0Bytes 0 0 0 completed 0.00
serverd.lab.example.com 0 0Bytes 0 0 0 completed 0.00
volume rebalance: important: success
2. 脚本评分
[root@workstation ~]# lab extendvolume-lab grade
3. 重置环境
reset workstation,servera,serverb,serverc,serverd
总结
-
介绍如何进行缩容volume。
-
了解执行数据均衡过程。
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