查看rbd对象以及组成
创建format 2格式的image 加上–image-format=2参数，下面直接看下rbd format2下有哪些对象
[root@node1 ~]# rbd create image –size 100M –image-format=2
[root@node1 ~]# rados ls -p rbd
rbd_directory
rbd_id.image
rbd_header.3289416b8b4567
**rbd_id.{image 名字}**
rbd_id对象的格式为：rbd\uid.{image name}head_hashpoolid
[root@node1 ~]# ceph osd map rbd rbd_id.image
osdmap e188 pool ‘rbd’ (0) object ‘rbd_id.image’ -> pg 0.1e6f8db0 (0.30) -> up ([2,0], p2) acting ([2,0], p2)
到osd2上 current下查看对象
[root@node2 ~]# cd /var/lib/ceph/osd/ceph-2/current/0.30_head/
[root@node2 0.30_head]# ll
total 4
-rw-r–r– 1 ceph ceph 0 Jan 31 15:32 __head_00000030__0
-rw-r–r– 1 ceph ceph 18 Mar 26 14:58 rbd\uid.image__head_1E6F8DB0__0
[root@node2 0.30_head]# cat rbd\\uid.image__head_1E6F8DB0__0
3289416b8b4567
cat查看到该对象存储的值为3289416b8b4567 ，也就是image这个块的id，与下面命令查看一致。其中文件最后_0表示的是pool id号 rbd池编号。
[root@node2 0.30_head]# rbd info image
rbd image ‘image’:
size 102400 kB in 25 objects
order 22 (4096 kB objects)
block_name_prefix: rbd_data.3289416b8b4567
format: 2
features: layering
flags:
**rbd_directory**
rbd_directory对象的命名格式为：rbd\udirectoryhead_hashpoolid
[root@node1 0.46_head]# ceph osd map rbd rbd_directory
osdmap e188 pool ‘rbd’ (0) object ‘rbd_directory’ -> pg 0.30a98c1c (0.1c) -> up ([1,2], p1) acting ([1,2], p1)
[root@node1 0.46_head]# pwd
/var/lib/ceph/osd/ceph-1/current/0.46_head
[root@node1 0.46_head]# cd ../0.1c_head/
[root@node1 0.1c_head]# ll
total 0
-rw-r–r– 1 ceph ceph 0 Jan 31 15:32 __head_0000001C__0
-rw-r–r– 1 ceph ceph 0 Mar 26 14:58 rbd\udirectory__head_30A98C1C__0
这个对象里面包含对应存储池里所有的image的name和id的双向映射
[root@node1 0.1c_head]# rados -p rbd listomapvals rbd_directory
id_3289416b8b4567
value (9 bytes) :
00000000 05 00 00 00 69 6d 61 67 65 |….image|
00000009
name_image
value (18 bytes) :
00000000 0e 00 00 00 33 32 38 39 34 31 36 62 38 62 34 35 |….3289416b8b45|
36 37 |67|
00000012
可以看到id对应的块的名字image，以及name_image（块名）对应的id号。
**rbd_header.{image id}**
rbd_header对象的格式为：rbd\uheader.{image id}head_hashpoolid
[root@node1 ~]# ceph osd map rbd rbd_header.3289416b8b4567
osdmap e188 pool ‘rbd’ (0) object ‘rbd_header.3289416b8b4567’ -> pg 0.d49b9246 (0.46) -> up ([0,1], p0) acting ([0,1], p0)
[root@node1 ~]# cd /var/lib/ceph/osd/ceph-1/current/0.46_head/
[root@node1 0.46_head]# ll
total 0
-rw-r–r– 1 ceph ceph 0 Jan 31 15:33 __head_00000046__0
-rw-r–r– 1 ceph ceph 0 Mar 26 14:58 rbd\uheader.3289416b8b4567__head_D49B9246__0
记录rbd image的元数据，其内容包括size，order，object_prefix, snapseq, parent（克隆的image才有）, snapshot{snap id}（各个快照的信息）。
通过listomapvals查看对象的各属性值（k/v）
[root@node1 0.46_head]# rados -p rbd listomapvals rbd_header.3289416b8b4567
features
value (8 bytes) :
00000000 01 00 00 00 00 00 00 00 |……..|
00000008
object_prefix
value (27 bytes) :
00000000 17 00 00 00 72 62 64 5f 64 61 74 61 2e 33 32 38 |….rbd_data.328|
00000010 39 34 31 36 62 38 62 34 35 36 37 |9416b8b4567|
0000001b
order
value (1 bytes) :
00000000 16 |.|
00000001
size
value (8 bytes) :
00000000 00 00 40 06 00 00 00 00 |..@…..|
00000008
snap_seq
value (8 bytes) :
00000000 00 00 00 00 00 00 00 00 |……..|
00000008
通过listomapkeys查看对象的key值
[root@node1 0.b_head]# rados -p rbd listomapkeys rbd_header.3289416b8b4567
features
object_prefix
order
size
snap_seq
**没有快照的image**
– object_prefix：对象的名字前缀
– order：用来计算block size的，比如22，那么块大小就是1<<22=4MB
– size：对象大小
– snap_seq：快照编号，没有快照的时候是0
**做过快照的image**
新增如下属性值
– snapshot_id：记录对应快照的信息
给image做快照
[root@node1 0.46_head]# rbd snap create rbd/image@snap_image
[root@node1 0.46_head]# rados -p rbd listomapvals rbd_header.3289416b8b4567
。。。
snap_seq
value (8 bytes) :
00000000 04 00 00 00 00 00 00 00 |……..|
00000008
snapshot_0000000000000004
value (87 bytes) :
00000000 04 01 51 00 00 00 04 00 00 00 00 00 00 00 0a 00 |..Q………….|
00000010 00 00 73 6e 61 70 5f 69 6d 61 67 65 00 00 40 06 |..snap_image..@.|
00000020 00 00 00 00 01 00 00 00 00 00 00 00 01 01 1c 00 |…………….|
00000030 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 fe ff |…………….|
00000040 ff ff ff ff ff ff 00 00 00 00 00 00 00 00 00 00 |…………….|
00000050 00 00 00 00 00 00 00 |…….|
00000057
**rbd_data.{image id}.{offset}**
rbd_data的对象命名格式为：rbd\udata.{image id}.fragementhead(snap)_hashpoolid
rbd image的数据对象，存放具体的数据内容。
列出对象
[root@node1 0.b_head]# rados ls -p rbd | grep 3289
rbd_data.3289416b8b4567.0000000000000006
rbd_data.3289416b8b4567.0000000000000012
rbd_data.3289416b8b4567.0000000000000017
rbd_data.3289416b8b4567.0000000000000001
rbd_data.3289416b8b4567.0000000000000018
rbd_data.3289416b8b4567.000000000000000c
rbd_header.3289416b8b4567
rbd_data.3289416b8b4567.0000000000000000
对第一个对象查看osd存储路径
[root@node1 mnt]# ceph osd map rbd rbd_data.3289416b8b4567.0000000000000006
osdmap e189 pool ‘rbd’ (0) object ‘rbd_data.3289416b8b4567.0000000000000006’ -> pg 0.2b7fe90b (0.b) -> up ([0,1], p0) acting ([0,1], p0)
[root@node1 mnt]# cd /var/lib/ceph/osd/ceph-1/current/0.b_head/
[root@node1 0.b_head]# ll
total 16
-rw-r–r– 1 ceph ceph 0 Jan 31 15:32 __head_0000000B__0
-rw-r–r– 1 ceph ceph 16384 Mar 26 18:05 rbd\udata.3289416b8b4567.0000000000000006__head_2B7FE90B__0
具体对象文件格式rbd\uid.块id.对象片段号—hash_poolid
