金鱼哥RHCA回忆录：RH236GlusterFS-管理分层

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概念和术语

能够基于用户的I/O，进行自动分类和数据移动。

tiering持续性的监控工作负载，识别热点数据，也就是用户经常访问的数据，通过统计和分析活跃的数据，将这些热点数据移到一个I/O比较快的热区（比如SSD），而非热点数据移到比较慢的冷区（比如机械硬盘），过程不会造成I/O中断。

所谓热区、冷区，就是在一个volume内部，又划分成两个子volume，一个热区，一个冷区。

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分层架构

分层转换器基于 DHT 和重新平衡逻辑，将一个卷分割为两个子卷：hot 和 cold。hot 子卷被视为 cold 子卷的缓存。转换器负责决定将哪一分层用于文件，以及何时在分层之间迁移文件。一个文件可以驻留于任一个卷，但一个文件不能分割到两个子卷上。文件迁移按照以下条件发生：

• 热度：文件被访问的频率。
• 容量：达到了 hot 子卷的容量（或水位）。

cluster.watermark-hi和cluster.watermark-low是高水位和低水位。

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数据移动框架

数据移动框架是利用重新平衡逻辑的迁移逻辑一般化。用于迁移文件的触发器由应用驱动。文件被升级或降级到适当的分层。可以配置文件的升级和降级检查频率，以适合具体的 glusterfs 架构。

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数据移动触发器

数据移动触发器是触发文件从源存储单元到目标存储单元的机制。源存储单元 (SSU) 和目标存储单元 (DSU) 分别指定从中迁移出数据的 glusterfs brick/卷，以及迁移后数据所驻留的 glusterfs brick/卷。数据移动触发器将创建数据移动请求 (DMR)，该请求将提交至数据移动服务 (DMS)。触发器有两个，即 I/O Path Trigger和 Scanning Trigger。

• I/O Path Trigger

当文件符合指定的数据移动规则时，此触发器将启动。

• Scanner Trigger

根据指定的移动规则，Scanner Trigger 遍历指定的源单元并选择对象/文件。在选择对象/文件后，向数据移动服务提交数据移动请求。

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数据移动服务 (DMS)

数据移动服务负责数据的实际移动。此服务接收由数据移动触发器提交的数据移动请求。数据移动请求指定用于处理该请求的适当插件。

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配置管理tiering

创建热区

注意：如果有geo-replication，必须先停掉
#gluster volume geo-replication vol1 desktop::vol1-slave stop

添加热区：
向一个已经存在的volume中，添加一个热区子卷，这个热区由两个brick组成的一个复制份数为2 的子卷
# gluster volume tier vol1 attach replica 2 \ 
node3:/brick/brick1 
node4:/brick/brick1 

查看卷信息，可以看到有tire信息：
# gluster volume info vol1 

查看热区状态：
# gluster volume tier vol1 status 

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移除热区

先迁移数据

# gluster volume tier vol1 detach start 

查看状态，状态都是completed时，就可以提交移除了
# gluster volume tier vol1 status 

提交状态，确认已完成数据迁移，并移除热区
# gluster volume tier vol1 detach commit 

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设置阀值

也就是说数据被读写次数达到多少的时候，它就成为一个热点数据
# gluster volume set vol1 cluster.read-freq-threshold 500 
# gluster volume set vol1 cluster.write-freq-threshold 500 
值在0-1000之间，如果为0，表示此功能不起作用
其余详见课本。

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扩容热区

1.先将热区detach

2.再attach热区，只不过这次tach的时候，多加几个brick

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课本练习（以练习来进行了解）

[root@workstation ~]# lab tiering setup

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1. 验证volume和brick的情况。

[root@servera ~]#  gluster volume info prod-vol 
 
Volume Name: prod-vol
Type: Replicate
Volume ID: 23354de6-241b-43ef-93ea-c19161939b00
Status: Started
Number of Bricks: 1 x 2 = 2
Transport-type: tcp
Bricks:
Brick1: servera:/bricks/brick-a1/brick
Brick2: serverb:/bricks/brick-b1/brick
Options Reconfigured:
performance.readdir-ahead: on

[root@workstation ~]# for I in server{a,b}
> do
> ssh ${I} "mount | grep brick"
> done
/dev/mapper/vg_bricks-brick--a1 on /bricks/brick-a1 type xfs (rw,relatime,seclabel,attr2,inode64,logbsize=64k,sunit=128,swidth=128,noquota)
/dev/mapper/vg_bricks-brick--a2 on /bricks/brick-a2 type xfs (rw,relatime,seclabel,attr2,inode64,logbsize=64k,sunit=128,swidth=128,noquota)
/dev/mapper/vg_bricks-brick--b1 on /bricks/brick-b1 type xfs (rw,relatime,seclabel,attr2,inode64,logbsize=64k,sunit=128,swidth=128,noquota)
/dev/mapper/vg_bricks-brick--b2 on /bricks/brick-b2 type xfs (rw,relatime,seclabel,attr2,inode64,logbsize=64k,sunit=128,swidth=128,noquota)

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2. 创建热区。

[root@servera ~]# gluster volume tier prod-vol attach replica 2 servera:/bricks/brick-a2/brick serverb:/bricks/brick-b2/brick
volume attach-tier: success
Tiering Migration Functionality: prod-vol: success: Attach tier is successful on prod-vol. use tier status to check the status.
ID: 378d1cd9-afbb-4509-b692-59ff548a4c63

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3. 验证卷信息

[root@servera ~]#  gluster volume info prod-vol 
Volume Name: prod-vol
Type: Tier
Volume ID: 23354de6-241b-43ef-93ea-c19161939b00
Status: Started
Number of Bricks: 4
Transport-type: tcp
Hot Tier :
Hot Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick1: serverb:/bricks/brick-b2/brick
Brick2: servera:/bricks/brick-a2/brick
Cold Tier:
Cold Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick3: servera:/bricks/brick-a1/brick
Brick4: serverb:/bricks/brick-b1/brick
Options Reconfigured:
cluster.tier-mode: cache
features.ctr-enabled: on
performance.readdir-ahead: on

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4. 验证启用状态。

[root@servera ~]#  gluster volume tier prod-vol status
Node                 Promoted files       Demoted files        Status              
---------            ---------            ---------            ---------           
localhost            0                    0                    in progress         
serverb.lab.example.com 0                    0                    in progress

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5. 脚本评分。

[root@workstation ~]# lab tiering grade

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课本练习（以练习来进行了解）

[root@workstation ~]# lab extend-tier setup

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1. 明确热区

[root@servera ~]# gluster volume info prod-vol 
Volume Name: prod-vol
Type: Tier
Volume ID: 2e225516-2b43-4dc7-869d-4252bd8cfe51
Status: Started
Number of Bricks: 4
Transport-type: tcp
Hot Tier :
Hot Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick1: serverb:/bricks/brick-b2/brick
Brick2: servera:/bricks/brick-a2/brick
Cold Tier:
Cold Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick3: servera:/bricks/brick-a1/brick
Brick4: serverb:/bricks/brick-b1/brick
Options Reconfigured:
cluster.tier-mode: cache
features.ctr-enabled: on
performance.readdir-ahead: on

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2. 按要求扩容热区。

[root@servera ~]# gluster volume tier prod-vol detach start
volume detach-tier start: success
ID: 4a91fea8-f81a-4736-8801-00b19c9ea6ca
[root@servera ~]# gluster volume tier prod-vol detach status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost                0        0Bytes            20             0             0            completed               2.00
                 serverb.lab.example.com               20       391.0KB            20             0             0            completed               2.00

[root@servera ~]# gluster volume tier prod-vol detach commit
Removing tier can result in data loss. Do you want to Continue? (y/n) y
volume detach-tier commit: success
Check the detached 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.

[root@servera ~]# rm -rf /bricks/brick-a2/brick
[root@servera ~]# mkdir /bricks/brick-a2/brick
[root@serverb ~]# rm -rf /bricks/brick-b2/brick
[root@serverb ~]# mkdir /bricks/brick-b2/brick

[root@servera ~]# gluster volume tier prod-vol attach replica 2 servera:/bricks/brick-a2/brick serverb:/bricks/brick-b2/brick servera:/bricks/brick-a3/brick serverb:/bricks/brick-b3/brick
volume attach-tier: success
Tiering Migration Functionality: prod-vol: success: Attach tier is successful on prod-vol. use tier status to check the status.
ID: e7b7c5aa-9548-48ec-8afd-bc09778f9c82

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3. 明确创建好的热区。

[root@servera ~]# gluster volume info prod-vol 
Volume Name: prod-vol
Type: Tier
Volume ID: 2e225516-2b43-4dc7-869d-4252bd8cfe51
Status: Started
Number of Bricks: 6
Transport-type: tcp
Hot Tier :
Hot Tier Type : Distributed-Replicate
Number of Bricks: 2 x 2 = 4
Brick1: serverb:/bricks/brick-b3/brick
Brick2: servera:/bricks/brick-a3/brick
Brick3: serverb:/bricks/brick-b2/brick
Brick4: servera:/bricks/brick-a2/brick
Cold Tier:
Cold Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick5: servera:/bricks/brick-a1/brick
Brick6: serverb:/bricks/brick-b1/brick
Options Reconfigured:
cluster.tier-mode: cache
features.ctr-enabled: on
performance.readdir-ahead: on

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4. 明确热区。

[root@servera ~]# gluster volume info dev-vol 
Volume Name: dev-vol
Type: Tier
Volume ID: c7b4ae35-4575-4dbc-abcc-4bef7d5be671
Status: Started
Number of Bricks: 6
Transport-type: tcp
Hot Tier :
Hot Tier Type : Distributed-Replicate
Number of Bricks: 2 x 2 = 4
Brick1: serverb:/bricks/brick-b6/brick
Brick2: servera:/bricks/brick-a6/brick
Brick3: serverb:/bricks/brick-b5/brick
Brick4: servera:/bricks/brick-a5/brick
Cold Tier:
Cold Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick5: servera:/bricks/brick-a4/brick
Brick6: serverb:/bricks/brick-b4/brick
Options Reconfigured:
cluster.tier-mode: cache
features.ctr-enabled: on
performance.readdir-ahead: on

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5. 按要求进行缩容热区。

[root@servera ~]# gluster volume tier dev-vol detach start
volume detach-tier start: success
ID: c65bd110-4c20-4ff5-9539-f5af843b4624
[root@servera ~]# gluster volume tier dev-vol detach status
                                    Node Rebalanced-files          size       scanned      failures       skipped               status   run time in secs
                               ---------      -----------   -----------   -----------   -----------   -----------         ------------     --------------
                               localhost                0        0Bytes             0             0             0            completed               0.00
                 serverb.lab.example.com                0        0Bytes            22             0             0            completed               0.00

[root@servera ~]# gluster volume tier dev-vol detach commit
Removing tier can result in data loss. Do you want to Continue? (y/n) y
volume detach-tier commit: success
Check the detached 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.

[root@servera ~]# rm -rf /bricks/brick-a6/brick/
[root@servera ~]# mkdir /bricks/brick-a6/brick
[root@serverb ~]# rm -rf /bricks/brick-b6/brick
[root@serverb ~]# mkdir /bricks/brick-b6/brick

[root@servera ~]# gluster volume tier dev-vol attach replica 2 servera:/bricks/brick-a6/brick serverb:/bricks/brick-b6/brick
volume attach-tier: success
Tiering Migration Functionality: dev-vol: success: Attach tier is successful on dev-vol. use tier status to check the status.
ID: 9d46db5b-c22b-43b5-bcd7-afe8c03d992d

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6. 明确缩容后的热区。

[root@servera ~]# gluster volume info dev-vol 
Volume Name: dev-vol
Type: Tier
Volume ID: c7b4ae35-4575-4dbc-abcc-4bef7d5be671
Status: Started
Number of Bricks: 4
Transport-type: tcp
Hot Tier :
Hot Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick1: serverb:/bricks/brick-b6/brick
Brick2: servera:/bricks/brick-a6/brick
Cold Tier:
Cold Tier Type : Replicate
Number of Bricks: 1 x 2 = 2
Brick3: servera:/bricks/brick-a4/brick
Brick4: serverb:/bricks/brick-b4/brick
Options Reconfigured:
cluster.tier-mode: cache
features.ctr-enabled: on
performance.readdir-ahead: on

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7. 脚本评分。

[root@workstation ~]# lab extend-tier grade

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总结

RHCA认证需要经历5门的学习与考试，还是需要花不少时间去学习与备考的，好好加油，可以噶🤪。

以上就是【金鱼哥】对 第十一章 GlusterFS-管理分层 的简述和讲解。希望能对看到此文章的小伙伴有所帮助。

💾红帽认证专栏系列：
RHCSA专栏：戏说 RHCSA 认证
RHCE专栏：戏说 RHCE 认证
此文章收录在RHCA专栏：RHCA 回忆录

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