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ceph的使用

2024-07-13 06:49:41   227人阅读

Ceph uniquely delivers object, block, and file storage in one unified system.
ceph提供了filesystem, block device, object store三种使用方式.
准确来说下面我们只讲它的block device,由于他们的基础都是要有一个可工作的Ceph Storage Cluster,因此这里先补充说明一些命令.

1.ceph相关命令

1)查看监控集群状态:

ceph health
ceph status
ceph osd stat
ceph osd dump
ceph osd tree
ceph mon dump
ceph quorum_status
ceph mds stat
ceph mds dump

你可以分别试试看这些命令.
2)pools 大概可以理解为命名空间
查看已经存在的pools

[root@test-2 ~]# ceph osd lspools
0 data,1 metadata,2 rbd,

查看data pool中的pg_num属性

[root@test-1 ~]# ceph osd pool get data pg_num
pg_num: 256

查看data pool中的pgp_num属性

[root@test-1 ~]# ceph osd pool get data pgp_num
pgp_num: 256

创建一个pool ‘test-pool’

[root@test-1 ~]# ceph osd pool create test-pool 256 256
pool ‘test-pool‘ created
[root@test-1 ~]# ceph osd lspools
0 data,1 metadata,2 rbd,3 test-pool,

删除 ‘test-pool’

[root@test-1 ~]# ceph osd pool delete test-pool test-pool  --yes-i-really-really-mean-it
pool ‘test-pool‘ deleted
[root@test-1 ~]# ceph osd lspools
0 data,1 metadata,2 rbd,

3)CRUSH map相关
获取现有集群的crush map

[root@test-1 ~]# ceph osd getcrushmap -o crush.map
got crush map from osdmap epoch 734

反编译

[root@test-1 ~]# cat crush.txt
# begin crush map
 
# devices
device 0 osd.0
device 1 osd.1
device 2 osd.2
 
# types
type 0 osd
type 1 host
type 2 rack
type 3 row
type 4 room
type 5 datacenter
type 6 root
 
# buckets
host test-1 {
        id -2           # do not change unnecessarily
        # weight 1.000
        alg straw
        hash 0  # rjenkins1
        item osd.0 weight 1.000
}
host test-2 {
        id -4           # do not change unnecessarily
        # weight 1.000
        alg straw
        hash 0  # rjenkins1
        item osd.1 weight 1.000
}
host test-3 {
        id -5           # do not change unnecessarily
        # weight 1.000
        alg straw
        hash 0  # rjenkins1
        item osd.2 weight 1.000
}
rack unknownrack {
        id -3           # do not change unnecessarily
        # weight 3.000
        alg straw
        hash 0  # rjenkins1
        item test-1 weight 1.000
        item test-2 weight 1.000
        item test-3 weight 1.000
}
root default {
        id -1           # do not change unnecessarily
        # weight 3.000
        alg straw
        hash 0  # rjenkins1
        item unknownrack weight 3.000
}
 
# rules
rule data {
        ruleset 0
        type replicated
        min_size 1
        max_size 10
        step take default
        step chooseleaf firstn 0 type host
        step emit
}
rule metadata {
        ruleset 1
        type replicated
        min_size 1
        max_size 10
        step take default
        step chooseleaf firstn 0 type host
        step emit
}
rule rbd {
        ruleset 2
        type replicated
        min_size 1
        max_size 10
        step take default
        step chooseleaf firstn 0 type host
        step emit
}
 
# end crush map

仔细观察这个输出信息,是不是发现了些什么有意思的事?请看官方文档的说明CRUSH
当你修改好了以后编译crush map

crushtool -c crush.txt -o crush.map

将这个生成的crush map设置到集群中

ceph osd setcrushmap -i crush.map

2.ceph block device相关命令

1)基本操作
创建一个block device image

[root@test-1 ~]# rbd create test-image --size 1024 --pool test-pool 
[root@test-1 ~]# rbd ls test-pool
test-image

查看这个image的详细信息

[root@test-1 ~]# rbd --image test-image info --pool test-pool
rbd image ‘test-image‘:
        size 1024 MB in 256 objects
        order 22 (4096 kB objects)
        block_name_prefix: rb.0.1483.6b8b4567
        format: 1

删除这个image

[root@test-1 ~]# rbd rm test-image -p test-pool
Removing image: 100% complete...done.

2)Kernel Modules
有时候我们需要将image挂载到本地,同时修改image中的一些信息,这就需要用到了map操作.
首先我们需要在内核中载入rbd模块(请确保之前内核升级的时候已选上了rbd相关)

modprobe rbd

map test-image

rbd map test-image --pool test-pool --id admin

查看mapped的设备

[root@test-1 mycephfs]# rbd showmapped
id pool      image      snap device   
1  test-pool test-image -    /dev/rbd1

我们看下/dev/rbd1的磁盘信息,然后mkfs,再挂载到/mnt/mycephfs目录下,在向里面创建一个包含’hello world’字符串的文件

[root@test-1 ~]# fdisk -lu /dev/rbd1
 
Disk /dev/rbd1: 1073 MB, 1073741824 bytes
255 heads, 63 sectors/track, 130 cylinders, total 2097152 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 4194304 bytes / 4194304 bytes
Disk identifier: 0x00000000
 
[root@test-1 ~]# mkfs.ext4 /dev/rbd1
mke2fs 1.41.12 (17-May-2010)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
Stride=1024 blocks, Stripe width=1024 blocks
65536 inodes, 262144 blocks
13107 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=268435456
8 block groups
32768 blocks per group, 32768 fragments per group
8192 inodes per group
Superblock backups stored on blocks:
        32768, 98304, 163840, 229376
 
Writing inode tables: done                           
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: done
 
This filesystem will be automatically checked every 33 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.
[root@test-1 ~]# mount /dev/rbd1 /mnt/mycephfs/       
[root@test-1 ~]# ll /mnt/mycephfs/
total 16
drwx------ 2 root root 16384 Nov 27 13:40 lost+found
[root@test-1 ~]# cd /mnt/mycephfs/
[root@test-1 mycephfs]# ls
lost+found
[root@test-1 mycephfs]# echo ‘hello‘ > hello.txt
[root@test-1 mycephfs]# ls
hello.txt  lost+found
[root@test-1 mycephfs]# df -h /mnt/mycephfs/
Filesystem            Size  Used Avail Use% Mounted on
/dev/rbd1             976M  1.3M  908M   1% /mnt/mycephfs

我们同时也可以改变image的容量大小

[root@test-1 mycephfs]# rbd resize --size 2048 test-image
rbd: error opening image test-image: (2) No such file or directory
2013-11-27 13:48:24.290564 7fcf3b185760 -1 librbd::ImageCtx: error finding header: (2) No such file or directory
[root@test-1 mycephfs]# rbd resize --size 2048 test-image --pool test-pool
Resizing image: 100% complete...done.
[root@test-1 mycephfs]# df -h /mnt/mycephfs/            
Filesystem            Size  Used Avail Use% Mounted on
/dev/rbd1             976M  1.3M  908M   1% /mnt/mycephfs
[root@test-1 mycephfs]# blockdev --getsize64 /dev/rbd1
2147483648
[root@test-1 mycephfs]# resize2fs /dev/rbd1
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/rbd1 is mounted on /mnt/mycephfs; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/rbd1 to 524288 (4k) blocks.
The filesystem on /dev/rbd1 is now 524288 blocks long.
 
[root@test-1 mycephfs]# df -h /mnt/mycephfs/
Filesystem            Size  Used Avail Use% Mounted on
/dev/rbd1             2.0G  1.6M  1.9G   1% /mnt/mycephfs
[root@test-1 mycephfs]# ls
hello.txt  lost+found

当我们修改完毕image内容后就可以unmap掉它了,之前你需要执行umount操作,当你下次map的时候之前创建的hello.txt依然会存在挂载目录下.

[root@test-1 mnt]# umount /dev/rbd1
[root@test-1 mnt]# rbd unmap /dev/rbd1

3)快照相关
有些时候我们需要对image进行snapshot操作,以便将来可以随时恢复到当时状态.
好我们对test-pool下的test-image进行snap操作

[root@test-1 mnt]# rbd snap create test-pool/test-image@mysnap
rbd: failed to create snapshot: (22) Invalid argument
2013-11-27 14:56:53.109819 7f5bea81d760 -1 librbd: failed to create snap id: (22) Invalid argument

提示错误:Invalid argument,搞了半天才知道问题出在’test-pool’, ‘test-image’名字中的’-’上面,
我们新建个pool叫’mypool’同时在下面创建一个’myimage’

[root@test-1 ceph]# ceph osd pool create mypool 256 256
pool ‘mypool‘ created
[root@test-1 ceph]# rbd create myimage --size 1024 --pool mypool
[root@test-1 ceph]# rbd --pool mypool ls
myimage

好,接下来创建snap,快照名字叫’snapimage’

[root@test-1 ceph]# rbd snap create mypool/myimage@snapimage

查看myimage的snap

[root@test-1 ceph]# rbd snap ls mypool/myimage
SNAPID NAME         SIZE
     2 snapimage 1024 MB

接下来我们测试下这个snap吧

[root@test-1 ceph]# rbd snap create mypool/myimage@snapimage3
[root@test-1 ceph]# rbd map mypool/myimage
[root@test-1 ceph]# mount /dev/rbd1 /mnt/mycephfs/
[root@test-1 ceph]# ls /mnt/mycephfs/
hello.txt  lost+found
[root@test-1 ceph]# echo  ‘welcome to zhengtianbao.com ‘ > /mnt/mycephfs/info.txt
[root@test-1 ceph]# ls /mnt/mycephfs/
hello.txt  info.txt  lost+found
[root@test-1 ceph]# umount /dev/rbd1
[root@test-1 ceph]# rbd unmap /dev/rbd1
[root@test-1 ceph]# rbd snap rollback mypool/myimage@snapimage3
Rolling back to snapshot: 100% complete...done.
[root@test-1 ceph]# rbd map mypool/myimage
[root@test-1 ceph]# mount /dev/rbd1 /mnt/mycephfs/
[root@test-1 ceph]# ls /mnt/mycephfs/
hello.txt  lost+found

是不是如预计的那样myimage回到了snapimage3时候的状态,之后创建的info.txt已经消失了.
删除snap

[root@test-1 ceph]# rbd snap ls mypool/myimage
SNAPID NAME          SIZE
     2 snapimage  1024 MB
     3 snapimage2 1024 MB
     4 snapimage3 1024 MB
[root@test-1 ceph]# rbd snap rm mypool/myimage@snapimage
[root@test-1 ceph]# rbd snap ls mypool/myimage         
SNAPID NAME          SIZE
     3 snapimage2 1024 MB
     4 snapimage3 1024 MB

删除myimage的全部snapshot

[root@test-1 ceph]# rbd snap purge mypool/myimage
Removing all snapshots: 100% complete...done.

4)libvirt
与libvirt配合使用,libvirt中定义domain的device使用ceph block device.
关于libvirt,大体的就是一个中间层,与rbd配合使用的关系大概如下:

libvirt-->qemu-->librbd-->librados-->osds
                                |--->monitors  

有关libvirt和qemu以后有机会再补上.
另外,请确保qemu在configure的时候enable rbd.
首先需要有一个制作好的镜像,我这里用centos6的一个镜像

[root@test-1 ~]# file centos6
centos6: x86 boot sector; GRand Unified Bootloader, stage1 version 0x3, boot drive 0x80, 1st sector stage2 0x849d4, GRUB version 0.94; partition 1: ID=0x83, active, starthead 32, startsector 2048, 1024000 sectors; partition 2: ID=0x8e, starthead 221, startsector 1026048, 19945472 sectors, code offset 0x48

通过qemu-img convert命令将这个镜像放置到mypool中,取名为centos

[root@test-1 ceph]# qemu-img convert ~/centos6 rbd:mypool/centos
[root@test-1 ceph]# rbd ls --pool mypool
centos
myimage
[root@test-1 ceph]# rbd info centos --pool mypool
rbd image ‘centos‘:
        size 10240 MB in 2560 objects
        order 22 (4096 kB objects)
        block_name_prefix: rb.0.14d4.6b8b4567
        format: 1

然后我们创建一个libvirt需要用到的domain xml文件,这里只是个简单的例子
test.xml

<domaintype=‘kvm‘>
  <name>test-ceph</name>
  <memoryunit=‘KiB‘>4194304</memory>
  <currentMemoryunit=‘KiB‘>4194304</currentMemory>
  <vcpuplacement=‘static‘>4</vcpu>
  <os>
    <typearch=‘x86_64‘machine=‘pc-i440fx-1.5‘>hvm</type>
    <bootdev=‘hd‘/>
    <bootmenuenable=‘yes‘/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <clockoffset=‘utc‘/>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>restart</on_crash>
  <devices>
    <emulator>/usr/libexec/qemu-kvm</emulator>
    <disktype=‘network‘device=‘disk‘>
      <drivername=‘qemu‘type=‘raw‘/>
      <sourceprotocol=‘rbd‘name=‘mypool/centos‘>
        <hostname=‘localhost‘port=‘6789‘/>
      </source>
      <targetdev=‘hda‘bus=‘ide‘/>
      <addresstype=‘drive‘controller=‘0‘bus=‘0‘target=‘0‘unit=‘0‘/>
    </disk>
    <controllertype=‘ide‘index=‘0‘>
      <addresstype=‘pci‘domain=‘0x0000‘bus=‘0x00‘slot=‘0x01‘function=‘0x1‘/>
    </controller>
    <controllertype=‘usb‘index=‘0‘>
      <addresstype=‘pci‘domain=‘0x0000‘bus=‘0x00‘slot=‘0x01‘function=‘0x2‘/>
    </controller>
    <inputtype=‘tablet‘bus=‘usb‘/>
    <inputtype=‘mouse‘bus=‘ps2‘/>
    <graphicstype=‘vnc‘port=‘-1‘autoport=‘yes‘/>
    <video>
      <modeltype=‘vga‘ram=‘65536‘vram=‘9216‘heads=‘1‘/>
      <addresstype=‘pci‘domain=‘0x0000‘bus=‘0x00‘slot=‘0x02‘function=‘0x0‘/>
    </video>
    <memballoonmodel=‘virtio‘>
      <addresstype=‘pci‘domain=‘0x0000‘bus=‘0x00‘slot=‘0x05‘function=‘0x0‘/>
    </memballoon>
  </devices>
</domain>

接下来通过virsh命令创建虚拟机,查看vnc端口

[root@test-1 ceph]# virsh define test.xml
[root@test-1 ceph]# virsh list --all
 Id    Name                           State
----------------------------------------------------
 -     test-ceph                      shut off
 
[root@test-1 ceph]# virsh start test-ceph
Domain test-ceph started
 
[root@test-1 ceph]# virsh list
 Id    Name                           State
----------------------------------------------------
 1     test-ceph                      running
 
[root@test-1 ceph]# virsh vncdisplay 1
:0

ok,现在我们可以通过vnc客户端连接到host:5900端口的虚拟机中进行操作了,同时你也可以在虚拟机中测试下ceph的读写性能如何…

一些链接:

[1]IBM关于ceph的说明: http://www.ibm.com/developerworks/cn/linux/l-ceph/
[2]ceph架构方面: http://www.ustack.com/blog/ceph_infra/
[3]ceph性能测试: http://tech.uc.cn/?p=1223#more-1223


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