014 Ceph管理和自定义CRUSHMAP

 一、概念

1.1 Ceph集群写操作流程

client首先访问ceph monitor获取cluster map的一个副本，知晓集群的状态和配置

数据被转化为一个或多个对象，每个对象都具有对象名称和存储池名称

以PG数为基数做hash，将对象映射到一个PG

根据计算出的PG，再通过CRUSH算法得到存放数据的一组OSD位置（副本个数），第一个是主，后面是从

客户端获得OSD ID，直接和这些OSD通信并存放数据

注： 以上所有操作都是在客户端完成 的，不会影响ceph集群服务端性能

1.2 Crush和对象放置策略

Ceph使用CRUSH算法（Controlled Replication Under Scalable Hashing 可扩展哈希下的受控复制）来计算哪些OSD存放哪些对象

对象分配到PG中，CRUSH决定这些PG使用哪些OSD来存储对象。理想情况下，CRUSH会将数据均匀的分布到存储中

当添加新OSD或者现有的OSD出现故障时，Ceph使用CRUSH在活跃的OSD上重平衡数据

CRUSH map是CRUSH算法的中央配置机制，可通过调整CRUSH map来优化数据存放位置

默认情况下，CRUSH将对象放置到不同主机上的OSD中。可以配置CRUSH map和CRUSH rules，使对象放置到不同房间或者不同机柜的主机上的OSD中。也可以将SSD磁盘分配给需要高速存储的池

1.3 Crush map的组成部分

CRUSH hierarchy（层次结构）：一个树型结构，通常用于代表OSD所处的位置。默认情况下，有一个根bucket，它包含所有的主机bucket，而OSD则是主机bucket的树叶。这个层次结构允许我们自定义，对它重新排列或添加更多的层次，如将OSD主机分组到不同的机柜或者不同的房间

CRUSH rule（规则）：CRUSH rule决定如何从bucket中分配OSD pg。每个池必须要有一条CRUSH rule，不同的池可map不同的CRUSH rule

二、crushmap的解译编译和更新

[root@ceph2 ceph]# ceph osd getcrushmap -o ./crushmap.bin

[root@ceph2 ceph]# file ./crushmap.bin

./crushmap.bin: MS Windows icon resource - 8 icons, 2-colors

[root@ceph2 ceph]# crushtool -d crushmap.bin -o ./crushmap.txt

[root@ceph2 ceph]# vim ./crushmap.txt

[root@ceph2 ceph]# crushtool -c crushmap.txt -o crushmap.-new.bin

[root@ceph2 ceph]# ceph osd tree

ID CLASS WEIGHT TYPE NAME STATUS REWEIGHT PRI-AFF 
-1 0.13129 root default 
-3 0.04376 host ceph2 
0 hdd 0.01459 osd.0 up 1.00000 1.00000 
3 hdd 0.01459 osd.3 up 1.00000 1.00000 
6 hdd 0.01459 osd.6 up 1.00000 1.00000 
-7 0.04376 host ceph3 
2 hdd 0.01459 osd.2 up 1.00000 1.00000 
5 hdd 0.01459 osd.5 up 1.00000 1.00000 
8 hdd 0.01459 osd.8 up 1.00000 1.00000 
-5 0.04376 host ceph4 
1 hdd 0.01459 osd.1 up 1.00000 1.00000 
4 hdd 0.01459 osd.4 up 1.00000 1.00000 
7 hdd 0.01459 osd.7 up 1.00000 1.00000 

[root@ceph2 ceph]# vim ./crushmap.txt

配置项

host ceph3 {
        id -7                      # do not change unnecessarily  ，一个负整数，以便与存储设备id区分
        id -8 class hdd           # do not change unnecessarily
        # weight 0.044     
        alg straw2               #将pg map到osd时的算法，默认使用straw2
        hash 0  # rjenkins1      #每个bucket都有一个hash算法，目前Ceph支持rjenkins1算法，设为0即使用该算法
        item osd.2 weight 0.015  #一个bucket包含的其他bucket或者叶子
        item osd.5 weight 0.015
        item osd.8 weight 0.015
}

CRUSH map包含数据放置规则，默认有两个规则： replicated_rule和erasure-code

通过ceph osd crush rule ls可列出现有规则，也可以使用ceph osd crush rule dump打印规则详细详细

[root@ceph2 ceph]# ceph osd crush rule ls

[root@ceph2 ceph]# ceph osd crush rule dump

[
    {
        "rule_id": 0,
        "rule_name": "replicated_rule",
        "ruleset": 0,
        "type": 1,
        "min_size": 1,
        "max_size": 10,
        "steps": [
            {
                "op": "take",
                "item": -1,
                "item_name": "default"
            },
            {
                "op": "chooseleaf_firstn",
                "num": 0,
                "type": "host"
            },
            {
                "op": "emit"
            }
        ]
    },
    {
        "rule_id": 1,
        "rule_name": "EC-pool",
        "ruleset": 1,
        "type": 3,
        "min_size": 3,
        "max_size": 5,
        "steps": [
            {
                "op": "set_chooseleaf_tries",
                "num": 5
            },
            {
                "op": "set_choose_tries",
                "num": 100
            },
            {
                "op": "take",
                "item": -1,
                "item_name": "default"
            },
            {
                "op": "chooseleaf_indep",
                "num": 0,
                "type": "host"
            },
            {
                "op": "emit"
            }
        ]
    }
]

 和配置文件crushmap一样

rule replicated_rule {
        id 0
        type replicated
        min_size 1
        max_size 10
        step take default
        step chooseleaf firstn 0 type host
        step emit
}
rule <rulename> {
id <id > [整数，规则id]
type [replicated|erasure] [规则类型，用于复制池还是纠删码池]
min_size <min-size> [如果池的最小副本数小于该值，则不会为当前池应用这条规则]
max_size <max-size>[如果创建的池的最大副本大于该值，则不会为当前池应用这条规则]
step take <bucket type> [这条规则作用的bucket，默认为default]
step [chooseleaf|choose] [firstn] <num> type <bucket-type> 
# num == 0 选择N（池的副本数）个bucket
# num > 0且num < N 选择num个bucket
# num < 0 选择N-num(绝对值)个bucket
step emit
}

创建一个复制池：

[root@ceph2 ceph]# ceph osd pool create testpool 32 32
pool 'testpool' already exists
[root@ceph2 ceph]# ceph osd pool set tetspool size 11
Error ENOENT: unrecognized pool 'tetspool'             #crush规则最大为10 修改crushrule

[root@ceph2 ceph]# vim crushmap.txt

rule replicated1_rule {
        id 2
        type replicated
        min_size 1
        max_size 11
        step take default
        step chooseleaf firstn 0 type host
        step emit
}

[root@ceph2 ceph]# vim crushmap.txt

[root@ceph2 ceph]# crushtool -c crushmap.txt -o crushmap-new.bin

[root@ceph2 ceph]# ceph osd setcrushmap -i crushmap-new.bin

[root@ceph2 ceph]# ceph osd crush rule ls

[root@ceph2 ceph]# ceph osd pool get testpool all

size: 3
min_size: 2
crash_replay_interval: 0
pg_num: 128
pgp_num: 128
crush_rule: replicated_rule
hashpspool: true
nodelete: false
nopgchange: false
nosizechange: false
write_fadvise_dontneed: false
noscrub: false
nodeep-scrub: false
use_gmt_hitset: 1
auid: 0
fast_read: 0

三、从命令行更新Crush map参数

3.1 默认bucket类型

type 0 osd，type 1 host，type 2 chassis，type 3 rack，type 4 row，type 5 pdu

type 6 pod，type 7 room，type 8 datacenter，type 9 region，type 10 root

图解

 

四、从命令行更新CRUSH map的 层次结构

4.1 创建bucket

[root@ceph2 ceph]# ceph osd crush add-bucket DC1 datacenter
added bucket DC1 type datacenter to crush map

4.2 检查

[root@ceph2 ceph]# ceph osd getcrushmap -o crushmap.bin

[root@ceph2 ceph]# crushtool -d crushmap.bin -o crushmap.txt

[root@ceph2 ceph]# vim crushmap.txt

datacenter DC1 {
        id -9           # do not change unnecessarily
        # weight 0.000
        alg straw2
        hash 0  # rjenkins1
}

 [root@ceph2 ceph]#  ceph osd  tree

4.3 删除

[root@ceph2 ceph]# vim crushmap.txt

这一段删除
datacenter DC1 {
        id -9           # do not change unnecessarily
        # weight 0.000
        alg straw2
        hash 0  # rjenkins1
}

4.4 编译导入

[root@ceph2 ceph]# crushtool -c crushmap.txt -o crushmap-new.bin

[root@ceph2 ceph]# ceph osd setcrushmap -i crushmap-new.bin

已经删除

[root@ceph2 ceph]# ceph osd tree

4.5 重新创建bucket

[root@serverc ~]# ceph osd crush add-bucket dc1 root
added bucket dc1 type root to crush map

五、规划新的bucket

5.1 定义三个rack

[root@ceph2 ceph]# ceph osd crush add-bucket  rack1 rack
added bucket rack1 type rack to crush map
[root@ceph2 ceph]# ceph osd crush add-bucket  rack2 rack
added bucket rack2 type rack to crush map
[root@ceph2 ceph]# ceph osd crush add-bucket  rack3 rack
added bucket rack3 type rack to crush map

5.2 把三个rack加入到dc1

[root@ceph2 ceph]# ceph osd crush  move rack1 root=dc1
moved item id -10 name 'rack1' to location {root=dc1} in crush map
[root@ceph2 ceph]# ceph osd crush  move rack2 root=dc1
moved item id -11 name 'rack2' to location {root=dc1} in crush map
[root@ceph2 ceph]# ceph osd crush  move rack3 root=dc1
moved item id -12 name 'rack3' to location {root=dc1} in crush map

5.3 把三个主机移动到rack中

由于move过去，默认就没有主机了，可以只用link连接过去

[root@ceph2 ceph]# ceph osd crush link ceph2 rack=rack1
linked item id -3 name 'ceph2' to location {rack=rack1} in crush map
[root@ceph2 ceph]# ceph osd crush link ceph2 rack=rack2
linked item id -3 name 'ceph2' to location {rack=rack2} in crush map
[root@ceph2 ceph]# ceph osd crush link ceph3 rack=rack2
linked item id -7 name 'ceph3' to location {rack=rack2} in crush map
[root@ceph2 ceph]# ceph osd crush link ceph4 rack=rack2
linked item id -5 name 'ceph4' to location {rack=rack2} in crush map

[root@ceph2 ceph]# ceph osd tree

5.4 修改

发现命令行配置错误，修改crushmap规则

原配置
rack rack1 {
        id -10          # do not change unnecessarily
        id -15 class hdd                # do not change unnecessarily
        # weight 0.045
        alg straw2
        hash 0  # rjenkins1
        item ceph2 weight 0.045
}
rack rack2 {
        id -11          # do not change unnecessarily
        id -14 class hdd                # do not change unnecessarily
        # weight 0.135
        alg straw2
        hash 0  # rjenkins1
        item ceph2 weight 0.045
        item ceph3 weight 0.045
        item ceph4 weight 0.045
}
rack rack3 {
        id -12          # do not change unnecessarily
        id -13 class hdd                # do not change unnecessarily
        # weight 0.000
        alg straw2
        hash 0  # rjenkins1
}

修改

rack rack1 {
        id -10          # do not change unnecessarily
        id -15 class hdd                # do not change unnecessarily
        # weight 0.045
        alg straw2
        hash 0  # rjenkins1
        item ceph2 weight 0.045
}
rack rack2 {
        id -11          # do not change unnecessarily
        id -14 class hdd                # do not change unnecessarily
        # weight 0.135
        alg straw2
        hash 0  # rjenkins1
        item ceph3 weight 0.045
}
rack rack3 {
        id -12          # do not change unnecessarily
        id -13 class hdd                # do not change unnecessarily
        # weight 0.000
        alg straw2
        hash 0  # rjenkins1
        item ceph4 weight 0.045
}

5.5 编译导入

[root@ceph2 ceph]# crushtool -c crushmap.txt -o crushmap-new.bin 
[root@ceph2 ceph]# ceph osd  setcrushmap -i crushmap-new.bin
29

 [root@ceph2 ceph]# ceph osd tree

5.6 创建一个故障域为rack级别的rule

[root@ceph2 ceph]# ceph osd crush rule create-replicated indc1 dc1 rack

[root@ceph2 ceph]# ceph osd getcrushmap -o ./crushmap.bin

[root@ceph2 ceph]# crushtool -d ./crushmap.bin -o ./crushmap.txt

[root@ceph2 ceph]# vim ./crushmap.txt

rule indc1 {
        id 3
        type replicated
        min_size 1
        max_size 10
        step take dc1
        step chooseleaf firstn 0 type rack
        step emit
}

5.7 创建一个池检测

[root@ceph2 ceph]# ceph osd pool create test 32 32
pool 'test' created
[root@ceph2 ceph]# ceph osd pool application  enable  test  rbd
enabled application 'rbd' on pool 'test'
[root@ceph2 ceph]# ceph osd pool get  test all
size: 3
min_size: 2
crash_replay_interval: 0
pg_num: 32
pgp_num: 32
crush_rule: replicated_rule
hashpspool: true
nodelete: false
nopgchange: false
nosizechange: false
write_fadvise_dontneed: false
noscrub: false
nodeep-scrub: false
use_gmt_hitset: 1
auid: 0
fast_read: 0

5.8 修改crushmap规则

[root@ceph2 ceph]# ceph osd pool set test crush_rule indc1
set pool 16 crush_rule to indc1
[root@ceph2 ceph]# ceph osd pool get  test all
size: 3
min_size: 2
crash_replay_interval: 0
pg_num: 32
pgp_num: 32
crush_rule: indc1
hashpspool: true
nodelete: false
nopgchange: false
nosizechange: false
write_fadvise_dontneed: false
noscrub: false
nodeep-scrub: false
use_gmt_hitset: 1
auid: 0
fast_read: 0

5.9 创建一个对象测试

[root@ceph2 ceph]# rados -p test put test /etc/ceph/ceph.conf
[root@ceph2 ceph]# rados -p test ls
test
[root@ceph2 ceph]# ceph osd map test test
osdmap e239 pool 'test' (16) object 'test' -> pg 16.40e8aab5 (16.15) -> up ([5,6], p5) acting ([5,6,0], p5)
[root@ceph2 ceph]# cd  /var/lib/ceph/osd/ceph-0/current/
[root@ceph2 current]# ls
10.0_head  1.1f_head  13.5_head   14.20_head  1.48_head   15.26_head  1.53_head   15.5c_head  15.79_head  16.11_head  1.66_TEMP  1.79_head  5.2_head   6.5_head

六、 实现指定ssd的存储池

每一个主机上选择一块磁盘作为ssd
ceph2：osd.0 ceph3:osd.2 ceph4:osd.1

6.1 创建基于这些主机的bucket

[root@ceph2 current]# ceph osd crush add-bucket ceph2-ssd host
added bucket ceph2-ssd type host to crush map
[root@ceph2 current]# ceph osd crush add-bucket ceph3-ssd host
added bucket ceph3-ssd type host to crush map
[root@ceph2 current]# ceph osd crush add-bucket ceph4-ssd host
added bucket ceph4-ssd type host to crush map

 [root@ceph2 current]# ceph osd tree

6.2 创建root，并把三台主机添加进去

[root@ceph2 current]# ceph osd crush add-bucket ssd-root root
added bucket ssd-root type root to crush map
[root@ceph2 current]# ceph osd crush move ceph2-ssd root=ssd-root
moved item id -17 name 'ceph2-ssd' to location {root=ssd-root} in crush map
[root@ceph2 current]# ceph osd crush move ceph3-ssd root=ssd-root
moved item id -18 name 'ceph3-ssd' to location {root=ssd-root} in crush map
[root@ceph2 current]# ceph osd crush move ceph4-ssd root=ssd-root
moved item id -19 name 'ceph4-ssd' to location {root=ssd-root} in crush map

[root@ceph2 current]# ceph osd tree

6.3 在这些主机上只添加指定的ssd盘的osd

[root@ceph2 current]# ceph osd crush add osd.0 0.01500 root=ssd-root host=ceph2-ssd
add item id 0 name 'osd.0' weight 0.015 at location {host=ceph2-ssd,root=ssd-root} to crush map
[root@ceph2 current]# ceph osd crush add osd.2 0.01500 root=ssd-root host=ceph3-ssd
add item id 2 name 'osd.2' weight 0.015 at location {host=ceph3-ssd,root=ssd-root} to crush map
[root@ceph2 current]# ceph osd crush add osd.1 0.01500 root=ssd-root host=ceph4-ssd
add item id 1 name 'osd.1' weight 0.015 at location {host=ceph4-ssd,root=ssd-root} to crush map

[root@ceph2 current]# ceph osd tree

6.4 创建一个crush rule，故障域基于主机级别

[root@ceph2 current]# ceph osd crush rule create-replicated ssdrule ssd-root host

6.5 创建一个池检测

[root@ceph2 current]# ceph osd pool create ssdpool 32 32 replicated ssdrule
pool 'ssdpool' created
[root@ceph2 current]# ceph osd pool get ssdpool all
size: 3
min_size: 2
crash_replay_interval: 0
pg_num: 32
pgp_num: 32
crush_rule: ssdrule
hashpspool: true
nodelete: false
nopgchange: false
nosizechange: false
write_fadvise_dontneed: false
noscrub: false
nodeep-scrub: false
use_gmt_hitset: 1
auid: 0
fast_read: 0
[root@ceph2 current]# rados -p ssdpool put test  /etc/ceph/ceph.conf
[root@ceph2 current]# rados -p ssdpool ls
test
[root@ceph2 current]# ceph osd map ssdpool test
osdmap e255 pool 'ssdpool' (17) object 'test' -> pg 17.40e8aab5 (17.15) -> up ([2,1,0], p2) acting ([2,1,0], p2)

6.6 保证两个root不冲突

可以把指定的ssd从dc1的root中去掉，保证两个root各用个的磁盘

[root@ceph2 current]# cd /etc/ceph/

[root@ceph2 ceph]# ceph osd getcrushmap -o crushmap.bin

41

[root@ceph2 ceph]# crushtool -d crushmap.bin -o crushmap.txt

[root@ceph2 ceph]# vim crushmap.txt

host ceph2 {
        id -3           # do not change unnecessarily
        id -4 class hdd         # do not change unnecessarily
        # weight 0.045
        alg straw2
        hash 0  # rjenkins1
        #item osd.0 weight 0.015
        item osd.3 weight 0.015
        item osd.6 weight 0.015
}
host ceph4 {
        id -5           # do not change unnecessarily
        id -6 class hdd         # do not change unnecessarily
        # weight 0.045
        alg straw2
        hash 0  # rjenkins1
        #item osd.1 weight 0.015
        item osd.4 weight 0.015
        item osd.7 weight 0.015
}
host ceph3 {
        id -7           # do not change unnecessarily
        id -8 class hdd         # do not change unnecessarily
        # weight 0.045
        alg straw2
        hash 0  # rjenkins1
        #item osd.2 weight 0.015
        item osd.5 weight 0.015
        item osd.8 weight 0.015
}

[root@ceph2 ceph]# crushtool -c crushmap.txt -o crushmap-new.bin

[root@ceph2 ceph]# ceph osd setcrushmap -i crushmap-new.bin

42

[root@ceph2 ceph]# ceph osd tree

ID  CLASS WEIGHT  TYPE NAME          STATUS REWEIGHT PRI-AFF 
-20       0.04500 root ssd-root                              
-17       0.01500     host ceph2-ssd                         
  0   hdd 0.01500         osd.0          up  1.00000 1.00000 
-18       0.01500     host ceph3-ssd                         
  2   hdd 0.01500         osd.2          up  1.00000 1.00000 
-19       0.01500     host ceph4-ssd                         
  1   hdd 0.01500         osd.1          up  1.00000 1.00000 
 -9       0.17999 root dc1                                   
-10       0.04500     rack rack1                             
 -3       0.04500         host ceph2                         
  3   hdd 0.01500             osd.3      up  1.00000 1.00000 
  6   hdd 0.01500             osd.6      up  1.00000 1.00000 
-11       0.13499     rack rack2                             
 -7       0.04500         host ceph3                         
  5   hdd 0.01500             osd.5      up  1.00000 1.00000 
  8   hdd 0.01500             osd.8      up  1.00000 1.00000 
-12             0     rack rack3                             
 -5       0.04500         host ceph4                         
  4   hdd 0.01500             osd.4      up  1.00000 1.00000 
  7   hdd 0.01500             osd.7      up  1.00000 1.00000 
 -1       0.13197 root default                               
 -3       0.04399     host ceph2                             
  3   hdd 0.01500         osd.3          up  1.00000 1.00000 
  6   hdd 0.01500         osd.6          up  1.00000 1.00000 
 -7       0.04399     host ceph3                             
  5   hdd 0.01500         osd.5          up  1.00000 1.00000 
  8   hdd 0.01500         osd.8          up  1.00000 1.00000 
 -5       0.04399     host ceph4                             
  4   hdd 0.01500         osd.4          up  1.00000 1.00000 
  7   hdd 0.01500         osd.7          up  1.00000 1.00000 

 各个的osd位于不同的root中，实验完成！！！

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博主声明：本文的内容来源主要来自誉天教育晏威老师，由本人实验完成操作验证，需要的博友请联系誉天教育（http://www.yutianedu.com/），获得官方同意或者晏老师（https://www.cnblogs.com/breezey/）本人同意即可转载，谢谢！