Openstack Cinder Ceph(RBD)备份恢复过程(backup/restore)_综合

转载：原文链接

概要：

本节我们讨论openstack cinder volume rbd驱动的 backup/restore操作。
Backup 是将 volume 备份到别的地方（备份设备），将来可以通过 restore 操作恢复。

Backup VS Snapshot
Backup 与 snapshot 都可以保存 volume 的当前状态，以备以后恢复。但二者在用途和实现上还是有区别的，具体表现在：

Snapshot 依赖于源 volume，不能独立存在；而 backup 不依赖源 volume，即便源 volume 不存在了，也可以 restore。
Snapshot 与源 volume 通常存放在一起，都由同一个 volume provider 管理；而 backup
存放在独立的备份设备中，有自己的备份方案和实现，与 volume provider 没有关系。

上面两点决定了 backup 具有容灾功能；而 snapshot 则提供 volume provider 内便捷的回溯功能。

一 RBD增量备份以及恢复原理

1 创建云盘test_volume1, size=1G

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd create volumes/test_volume1 --size 1G
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME         SIZE PARENT FMT PROT LOCK 
test_volume1 1GiB          2

2 创建test_volume1快照t1和t2

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd snap create volumes/test_volume1@test.snap.t1
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME                      SIZE PARENT FMT PROT LOCK 
test_volume1              1GiB          2           
test_volume1@test.snap.t1 1GiB          2           
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd snap create volumes/test_volume1@test.snap.t2
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME                      SIZE PARENT FMT PROT LOCK 
test_volume1              1GiB          2           
test_volume1@test.snap.t1 1GiB          2           
test_volume1@test.snap.t2 1GiB          2           
()[root@busybox-openstack-5c687fdc9-mpwjd /]#

3 创建增量diff

# diff from initial to t1
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd export-diff volumes/test_volume1@test.snap.t1 diff_t1_between_initial
Exporting image: 100% complete...done.
# diff from initial to t2
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd export-diff volumes/test_volume1@test.snap.t2 diff_t2_between_initial
Exporting image: 100% complete...done.
# diff from t1 to t2
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd export-diff --from-snap test.snap.t1 volumes/test_volume1@test.snap.t2 diff_t1_between_t2
Exporting image: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# ls -l |grep diff
-rw-r--r--     1 root root    39 Sep  4 10:52 diff_t1_between_initial
-rw-r--r--     1 root root    56 Sep  4 10:52 diff_t1_between_t2
-rw-r--r--     1 root root    39 Sep  4 10:52 diff_t2_between_initial

4 通过增量diff创建备份

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd create backups/backup_image --size 1G
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l backups
NAME         SIZE PARENT FMT PROT LOCK 
backup_image 1GiB          2    
# import diff from initial to t1
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd import-diff diff_t1_between_initial backups/backup_image
Importing image diff: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l backups
NAME                      SIZE PARENT FMT PROT LOCK 
backup_image              1GiB          2           
backup_image@test.snap.t1 1GiB          2   
# import diff from t1 to t2
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd import-diff diff_t1_between_t2 backups/backup_image
Importing image diff: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l backups
NAME                      SIZE PARENT FMT PROT LOCK 
backup_image              1GiB          2           
backup_image@test.snap.t1 1GiB          2           
backup_image@test.snap.t2 1GiB          2

二 ceph备份时实现：

1. 创建云盘volume-id，大小为1G

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd create volumes/volume-id --size 1G
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l volumes |grep volume-id
volume-id         1GiB                          2

2. 先尝试进行diff store，创建backups中的base盘

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd create backups/volume-volume-id.backup.base --size 1G
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l backups
NAME                         SIZE PARENT FMT PROT LOCK 
volume-volume-id.backup.base 1GiB          2

3. 创建volume-id快照1，命名规则如下

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd snap create volumes/volume-id@backup.backup-id.snap.time1
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l volumes |grep volume-id
volume-id                                 1GiB                       2           
volume-id@backup.backup-id.snap.time1     1GiB                       2

4. 导出云盘和快照1的差异1

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd export-diff volumes/volume-id@backup.backup-id.snap.time1 test_diff_snap_time1
Exporting image: 100% complete...done.
()[root@busybox-openstack-f7bcf88-hgdkz /]# ls
test_diff_snap_time1

5. 将差异1导入到backups的base盘中，此时base盘生成了一个快照

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd import-diff test_diff_snap_time1 backups/volume-volume-id.backup.base
Importing image diff: 100% complete...done.
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l backups
NAME                                                     SIZE PARENT FMT PROT LOCK 
volume-volume-id.backup.base                             1GiB          2           
volume-volume-id.backup.base@backup.backup-id.snap.time1 1GiB          2

6. 第二次做增量备份时，创建volume-id新的快照2

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd snap create volumes/volume-id@backup.backup-id2.snap.time2
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l backups
NAME                                                     SIZE PARENT FMT PROT LOCK 
volume-volume-id.backup.base                             1GiB          2           
volume-volume-id.backup.base@backup.backup-id.snap.time1 1GiB          2           
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l volumes |grep volume-id
volume-id                                                                                     1GiB                                                                                                        2           
volume-id@backup.backup-id.snap.time1                                                         1GiB                                                                                                        2           
volume-id@backup.backup-id2.snap.time2                                                        1GiB                                                                                                        2

7. 导出快照1和快照2的差异2

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd export-diff --snap backup.backup-id.snap.time1 volumes/volume-id@backup.backup-id2.snap.time2 test_diff_snap_time1_time2
Exporting image: 100% complete...done.

8. 将差异2导入backups的base盘，此时base盘又生成了一个新的快照

()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd import-diff test_diff_snap_time1_time2 backups/volume-volume-id.backup.base
Importing image diff: 100% complete...done.
()[root@busybox-openstack-f7bcf88-hgdkz /]# rbd ls -l backups
NAME                                                      SIZE PARENT FMT PROT LOCK 
volume-volume-id.backup.base                              1GiB          2           
volume-volume-id.backup.base@backup.backup-id.snap.time1  1GiB          2           
volume-volume-id.backup.base@backup.backup-id2.snap.time2 1GiB          2

9. 删除volume-id的快照1

10. 如果diff store出现异常，会通过full store来备份，通过将云盘按照chunk=128M分片拷贝数据到新的云盘。

11. 备份元数据

三 RBD恢复备份的实现：

1 先检查是否满足diff restore, 需要满足下面条件

check can  diff restore:
1 base exist: backups/volume-volume-id.backup.base
2 restore point snapshot exist: backups/volume-volume-id.backup.base@backup.backup-id.snap.time1
3 volume file is rbd
4 backup[volume_id] !=  new volume_id
5 rbd volume has no extents (extend)

2. 如果满足diff restore条件，先导出对应backup-id的差异

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd export-diff backups/volume-volume-id.backup.base@backup.backup-id1.snap.time1 test_diff_backup_id2
Exporting image: 100% complete...done.

3. 将对应backup-id的差异导入new-volume-id

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd import-diff test_diff_backup_id2 volumes/new-volume-id
Importing image diff: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME                                       SIZE PARENT FMT PROT LOCK 
new-volume-id                              1GiB          2           
new-volume-id@backup.backup-id1.snap.time1 1GiB          2           
volume-id                                  1GiB          2           
volume-id@backup.backup-id1.snap.time1     1GiB          2

4. 如果new volume的大小与备份的大小不一致，导入差异后需要resize。

()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd create volumes/new-volume-id2 --size 2G
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd import-diff test_diff_backup_id2 volumes/new-volume-id2
Importing image diff: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME                                        SIZE PARENT FMT PROT LOCK 
new-volume-id                               1GiB          2           
new-volume-id@backup.backup-id1.snap.time1  1GiB          2           
new-volume-id2                              1GiB          2           
new-volume-id2@backup.backup-id1.snap.time1 1GiB          2           
volume-id                                   1GiB          2           
volume-id@backup.backup-id1.snap.time1      1GiB          2           
()[root@busybox-openstack-5c687fdc9-mpwjd /]# 
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd resize volumes/new-volume-id2 --size 2G
Resizing image: 100% complete...done.
()[root@busybox-openstack-5c687fdc9-mpwjd /]# rbd ls -l volumes
NAME                                        SIZE PARENT FMT PROT LOCK 
new-volume-id                               1GiB          2           
new-volume-id@backup.backup-id1.snap.time1  1GiB          2           
new-volume-id2                              2GiB          2           
new-volume-id2@backup.backup-id1.snap.time1 1GiB          2           
volume-id                                   1GiB          2           
volume-id@backup.backup-id1.snap.time1      1GiB          2

5. 如果不满足diff restore条件，或者在diff restore过程中出现异常，进行full restore，通过将云盘按照chunk=128M分片拷贝数据到新的云盘。

6. 恢复元数据