关于onbar备份过程及原理
ontape的备份过程需要经历是个过程：
1.产生检查点
2.冻结逻辑日志，找到最近检查点后所有活动事务的逻辑日志
3.写入ontape的备份设置备份设置信息到备份的第一个数据页
4.将rootdbs中的保留页写到磁带缓存
5，开始备份上面的逻辑日志，将其写到磁带缓存
6，释放逻辑日志
7.备份chunk文件
8.备份完成关闭磁带设备，更新内存中的备份信息
9.产生一个检查点，将备份信息写到保留页中.完成检查点
10.打印输出备份完成的信息
以上是一个完整的ontape备份过程，掌握了其过程原理对我们日常管理维护和诊断帮助很大，但是对于onbar这块还是比较迷惑，相关资料少，欢迎大家讨论下。
1.产生检查点
2.冻结逻辑日志，找到最近检查点后所有活动事务的逻辑日志
3.写入ontape的备份设置备份设置信息到备份的第一个数据页
4.将rootdbs中的保留页写到磁带缓存
5，开始备份上面的逻辑日志，将其写到磁带缓存
6，释放逻辑日志
7.备份chunk文件
8.备份完成关闭磁带设备，更新内存中的备份信息
9.产生一个检查点，将备份信息写到保留页中.完成检查点
10.打印输出备份完成的信息
以上是一个完整的ontape备份过程，掌握了其过程原理对我们日常管理维护和诊断帮助很大，但是对于onbar这块还是比较迷惑，相关资料少，欢迎大家讨论下。
2同行回答
回复 1# marvelyu
对于onbar做了一个完整的备份测试，当时我的运行日志如下：
address number flags uniqid begin size used %used
45efcb30 1 U------ 762 1:25263 5000 5000 100.00
45efcb78 2 U------ 763 1:30263 5000 5000 100.00
45efcbc0 3 U------ 764 1:35263 5000 5000 100.00
45efcc08 4 U------ 765 1:40263 5000 5000 100.00
45efcc50 5 U------ 766 1:45263 5000 5000 100.00
45efcc98 6 U---C-L 767 1:61944 512 512 100.00
运行备份后观察其备份运行日志如下：
2011-02-23 10:26:44 16382 16380 /opt/IBM/informix/bin/onbar_d -b -w
2011-02-23 10:26:45 16382 16380 Begin backup logical log 762.
最先备份下一个需要切换的日志，然后依次备份各个日志
2011-02-23 10:26:45 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:26:51 16382 16380 Completed backup logical log 762 (Storage Manager copy ID: 1092997599 0).
2011-02-23 10:26:51 16382 16380 Begin backup logical log 763.
2011-02-23 10:26:51 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:26:54 16382 16380 Completed backup logical log 763 (Storage Manager copy ID: 1092997600 0).
2011-02-23 10:26:54 16382 16380 Begin backup logical log 764.
2011-02-23 10:26:54 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:00 16382 16380 Completed backup logical log 764 (Storage Manager copy ID: 1092997601 0).
2011-02-23 10:27:01 16382 16380 Begin backup logical log 765.
2011-02-23 10:27:01 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:07 16382 16380 Completed backup logical log 765 (Storage Manager copy ID: 1092997602 0).
2011-02-23 10:27:07 16382 16380 Begin backup logical log 766.
2011-02-23 10:27:07 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:15 16382 16380 Completed backup logical log 766 (Storage Manager copy ID: 1092997603 0).
2011-02-23 10:27:15 16382 16380 Begin backup logical log 767.
2011-02-23 10:27:15 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:16 16382 16380 Completed backup logical log 767 (Storage Manager copy ID: 1092997604 0)
这应该是读取保留页中的内容了：
2011-02-23 10:27:17 16382 16380 Archive started on rootdbs, userspace1, sbspace, adminspace (Requested Level 0).
开始rootdbs的0级备份：
2011-02-23 10:27:18 16382 16380 Begin level 0 backup rootdbs.
2011-02-23 10:27:18 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:30 16382 16380 Completed level 0 backup rootdbs (Storage Manager copy ID: 1092997605 0).
2011-02-23 10:27:31 16636 16382 Process 16636 16382 successfully forked.
2011-02-23 10:27:31 16637 16382 Process 16637 16382 successfully forked.
2011-02-23 10:27:32 16637 16382 Begin level 0 backup sbspace.
2011-02-23 10:27:33 16636 16382 Begin level 0 backup userspace1.
2011-02-23 10:27:33 16638 16382 Process 16638 16382 successfully forked.
2011-02-23 10:27:34 16638 16382 Begin level 0 backup adminspace.
2011-02-23 10:27:34 16637 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:35 16638 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:36 16636 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:48 16636 16382 Completed level 0 backup userspace1 (Storage Manager copy ID: 1092997607 0).
2011-02-23 10:28:20 16637 16382 Completed level 0 backup sbspace (Storage Manager copy ID: 1092997606 0).
2011-02-23 10:28:29 16636 16382 Process 16636 16382 completed.
2011-02-23 10:28:29 16637 16382 Process 16637 16382 completed.
2011-02-23 10:29:20 16638 16382 Completed level 0 backup adminspace (Storage Manager copy ID: 1092997608 0).
2011-02-23 10:29:20 16638 16382 Process 16638 16382 completed.
2011-02-23 10:29:21 16382 16380 Archive on rootdbs, userspace1, sbspace, adminspace Completed (Requested Level 0).
2011-02-23 10:29:21 16382 16380 Begin backup logical log 768.
2011-02-23 10:29:21 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:29:21 16382 16380 Completed backup logical log 768 (Storage Manager copy ID: 1092997609 0).
2011-02-23 10:29:22 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:29:23 16382 16380 /opt/IBM/informix/bin/onbar_d complete, returning 0 (0x00)
备份完成后提示备份完成。
同时online.log日志内容如下：
10:26:45 Logical Log 762 - Backup Started
2011-02-23 10:26:46 Servername:demo_on
<>> Logical Log Files are Full -- Backup is Needed
10:26:51 Logical Log 762 - Backup Completed
10:26:51 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 762." "Logical Log 762 - Backup Completed" ""
10:26:51 Checkpoint Completed: duration was 181 seconds.
10:26:51 Wed Feb 23 - loguniq 768, logpos 0x3bc, timestamp: 0x1c20697 Interval: 2440
10:26:51 Maximum server connections 5
10:26:51 Checkpoint Statistics - Avg. Txn Block Time 181.026, # Txns blocked 4, Plog used 4, Llog used 25
10:26:51 Logical Log 763 - Backup Started
2011-02-23 10:26:52 Servername:demo_on
<>> Logical Log 767 Complete, timestamp: 0x1c206d0.
10:26:52 Logical Log 767 Complete, timestamp: 0x1c206d0.
10:26:52 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 23 "" "Logical Log 767 Complete, timestamp: 0x1c206d0." ""
10:26:54 Logical Log 763 - Backup Completed
10:26:54 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 763." "Logical Log 763 - Backup Completed" ""
10:26:54 Logical Log 764 - Backup Started
10:27:00 Logical Log 764 - Backup Completed
10:27:00 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 764." "Logical Log 764 - Backup Completed" ""
10:27:01 Logical Log 765 - Backup Started
10:27:07 Logical Log 765 - Backup Completed
10:27:07 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 765." "Logical Log 765 - Backup Completed" ""
10:27:07 Logical Log 766 - Backup Started
10:27:15 Logical Log 766 - Backup Completed
10:27:15 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 766." "Logical Log 766 - Backup Completed" ""
10:27:15 Logical Log 767 - Backup Started
10:27:16 Logical Log 767 - Backup Completed
10:27:16 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 767." "Logical Log 767 - Backup Completed" ""
10:27:17 Checkpoint Completed: duration was 0 seconds.
10:27:17 Wed Feb 23 - loguniq 768, logpos 0xa3018, timestamp: 0x1c20bb4 Interval: 2441
10:27:17 Maximum server connections 5
10:27:17 Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 0, Plog used 17, Llog used 163
10:27:18 Level 0 Archive started on rootdbs
10:27:30 Archive on rootdbs Completed.
10:27:30 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'rootdbs'." "Archive on rootdbs Completed." ""
10:27:31 Level 0 Archive started on userspace1
10:27:32 Level 0 Archive started on sbspace
10:27:33 Dynamically allocated new virtual shared memory segment (size 8192KB)
10:27:33 Memory sizes:resident:28916 KB, virtual:40848 KB, SHMTOTAL:1048576 KB
10:27:34 Level 0 Archive started on adminspace
10:27:48 Archive on userspace1 Completed.
10:27:48 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'userspace1'." "Archive on userspace1 Completed." ""
10:28:20 Archive on sbspace Completed.
10:28:20 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'sbspace'." "Archive on sbspace Completed." ""
10:29:20 Archive on adminspace Completed.
可以看出备份中需要给备份进程分配共享虚拟内存空间收起
对于onbar做了一个完整的备份测试，当时我的运行日志如下：
address number flags uniqid begin size used %used
45efcb30 1 U------ 762 1:25263 5000 5000 100.00
45efcb78 2 U------ 763 1:30263 5000 5000 100.00
45efcbc0 3 U------ 764 1:35263 5000 5000 100.00
45efcc08 4 U------ 765 1:40263 5000 5000 100.00
45efcc50 5 U------ 766 1:45263 5000 5000 100.00
45efcc98 6 U---C-L 767 1:61944 512 512 100.00
运行备份后观察其备份运行日志如下：
2011-02-23 10:26:44 16382 16380 /opt/IBM/informix/bin/onbar_d -b -w
2011-02-23 10:26:45 16382 16380 Begin backup logical log 762.
最先备份下一个需要切换的日志，然后依次备份各个日志
2011-02-23 10:26:45 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:26:51 16382 16380 Completed backup logical log 762 (Storage Manager copy ID: 1092997599 0).
2011-02-23 10:26:51 16382 16380 Begin backup logical log 763.
2011-02-23 10:26:51 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:26:54 16382 16380 Completed backup logical log 763 (Storage Manager copy ID: 1092997600 0).
2011-02-23 10:26:54 16382 16380 Begin backup logical log 764.
2011-02-23 10:26:54 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:00 16382 16380 Completed backup logical log 764 (Storage Manager copy ID: 1092997601 0).
2011-02-23 10:27:01 16382 16380 Begin backup logical log 765.
2011-02-23 10:27:01 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:07 16382 16380 Completed backup logical log 765 (Storage Manager copy ID: 1092997602 0).
2011-02-23 10:27:07 16382 16380 Begin backup logical log 766.
2011-02-23 10:27:07 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:15 16382 16380 Completed backup logical log 766 (Storage Manager copy ID: 1092997603 0).
2011-02-23 10:27:15 16382 16380 Begin backup logical log 767.
2011-02-23 10:27:15 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:16 16382 16380 Completed backup logical log 767 (Storage Manager copy ID: 1092997604 0)
这应该是读取保留页中的内容了：
2011-02-23 10:27:17 16382 16380 Archive started on rootdbs, userspace1, sbspace, adminspace (Requested Level 0).
开始rootdbs的0级备份：
2011-02-23 10:27:18 16382 16380 Begin level 0 backup rootdbs.
2011-02-23 10:27:18 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:27:30 16382 16380 Completed level 0 backup rootdbs (Storage Manager copy ID: 1092997605 0).
2011-02-23 10:27:31 16636 16382 Process 16636 16382 successfully forked.
2011-02-23 10:27:31 16637 16382 Process 16637 16382 successfully forked.
2011-02-23 10:27:32 16637 16382 Begin level 0 backup sbspace.
2011-02-23 10:27:33 16636 16382 Begin level 0 backup userspace1.
2011-02-23 10:27:33 16638 16382 Process 16638 16382 successfully forked.
2011-02-23 10:27:34 16638 16382 Begin level 0 backup adminspace.
2011-02-23 10:27:34 16637 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:35 16638 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:36 16636 16382 Successfully connected to Storage Manager.
2011-02-23 10:27:48 16636 16382 Completed level 0 backup userspace1 (Storage Manager copy ID: 1092997607 0).
2011-02-23 10:28:20 16637 16382 Completed level 0 backup sbspace (Storage Manager copy ID: 1092997606 0).
2011-02-23 10:28:29 16636 16382 Process 16636 16382 completed.
2011-02-23 10:28:29 16637 16382 Process 16637 16382 completed.
2011-02-23 10:29:20 16638 16382 Completed level 0 backup adminspace (Storage Manager copy ID: 1092997608 0).
2011-02-23 10:29:20 16638 16382 Process 16638 16382 completed.
2011-02-23 10:29:21 16382 16380 Archive on rootdbs, userspace1, sbspace, adminspace Completed (Requested Level 0).
2011-02-23 10:29:21 16382 16380 Begin backup logical log 768.
2011-02-23 10:29:21 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:29:21 16382 16380 Completed backup logical log 768 (Storage Manager copy ID: 1092997609 0).
2011-02-23 10:29:22 16382 16380 Successfully connected to Storage Manager.
2011-02-23 10:29:23 16382 16380 /opt/IBM/informix/bin/onbar_d complete, returning 0 (0x00)
备份完成后提示备份完成。
同时online.log日志内容如下：
10:26:45 Logical Log 762 - Backup Started
2011-02-23 10:26:46 Servername:demo_on
<
10:26:51 Logical Log 762 - Backup Completed
10:26:51 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 762." "Logical Log 762 - Backup Completed" ""
10:26:51 Checkpoint Completed: duration was 181 seconds.
10:26:51 Wed Feb 23 - loguniq 768, logpos 0x3bc, timestamp: 0x1c20697 Interval: 2440
10:26:51 Maximum server connections 5
10:26:51 Checkpoint Statistics - Avg. Txn Block Time 181.026, # Txns blocked 4, Plog used 4, Llog used 25
10:26:51 Logical Log 763 - Backup Started
2011-02-23 10:26:52 Servername:demo_on
<
10:26:52 Logical Log 767 Complete, timestamp: 0x1c206d0.
10:26:52 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 23 "" "Logical Log 767 Complete, timestamp: 0x1c206d0." ""
10:26:54 Logical Log 763 - Backup Completed
10:26:54 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 763." "Logical Log 763 - Backup Completed" ""
10:26:54 Logical Log 764 - Backup Started
10:27:00 Logical Log 764 - Backup Completed
10:27:00 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 764." "Logical Log 764 - Backup Completed" ""
10:27:01 Logical Log 765 - Backup Started
10:27:07 Logical Log 765 - Backup Completed
10:27:07 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 765." "Logical Log 765 - Backup Completed" ""
10:27:07 Logical Log 766 - Backup Started
10:27:15 Logical Log 766 - Backup Completed
10:27:15 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 766." "Logical Log 766 - Backup Completed" ""
10:27:15 Logical Log 767 - Backup Started
10:27:16 Logical Log 767 - Backup Completed
10:27:16 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 18 "Log Backup completed: 767." "Logical Log 767 - Backup Completed" ""
10:27:17 Checkpoint Completed: duration was 0 seconds.
10:27:17 Wed Feb 23 - loguniq 768, logpos 0xa3018, timestamp: 0x1c20bb4 Interval: 2441
10:27:17 Maximum server connections 5
10:27:17 Checkpoint Statistics - Avg. Txn Block Time 0.000, # Txns blocked 0, Plog used 17, Llog used 163
10:27:18 Level 0 Archive started on rootdbs
10:27:30 Archive on rootdbs Completed.
10:27:30 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'rootdbs'." "Archive on rootdbs Completed." ""
10:27:31 Level 0 Archive started on userspace1
10:27:32 Level 0 Archive started on sbspace
10:27:33 Dynamically allocated new virtual shared memory segment (size 8192KB)
10:27:33 Memory sizes:resident:28916 KB, virtual:40848 KB, SHMTOTAL:1048576 KB
10:27:34 Level 0 Archive started on adminspace
10:27:48 Archive on userspace1 Completed.
10:27:48 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'userspace1'." "Archive on userspace1 Completed." ""
10:28:20 Archive on sbspace Completed.
10:28:20 Process exited with return code 3: /bin/sh /bin/sh -c /opt/IBM/informix/etc/alarmprogram.sh 2 16 "Archive completed: 'sbspace'." "Archive on sbspace Completed." ""
10:29:20 Archive on adminspace Completed.
可以看出备份中需要给备份进程分配共享虚拟内存空间收起
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