求助！手动db2 offline backup 失败

生产环境上，由于需求，需要手动offline backup，我用同样的命令在备份成功了在同一个server上的另一个DB，这个DB就怎么也备份不起。报错是

SQL1035N  The operation failed because the specified database cannot be

connected to in the mode requested.  SQLSTATE=57019

里面给的user response 我能做的都做了。。

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这是我用的命令：

[db2inst1/db2backup/WEB_OFFLINE_DEC23] # db2 connect to web

   Database Connection Information

Database server        = DB2/AIX64 10.5.5
SQL authorization ID   = DB2INST1
Local database alias   = WEB

[://db2backup/WEB_OFFLINE_DEC23] # db2 quiesce db immediate
SQL1371W  The quiesce operation was not executed because the specified
instance or database named  "ISMTWEB" is already quiesced.
://db2backup/WEB_OFFLINE_DEC23] # db2 force application all
DB20000I  The FORCE APPLICATION command completed successfully.
DB21024I  This command is asynchronous and may not be effective immediately.

[://db2backup/WEB_OFFLINE_DEC23] # db2 terminate
DB20000I  The TERMINATE command completed successfully.
[/db2backup/WEB_OFFLINE_DEC23] # db2 deactivate db ismtweb
DB20000I  The DEACTIVATE DATABASE command completed successfully.
[://db2backup/WEB_OFFLINE_DEC23] # nohup db2 backup database web to /db2backup/WEB_OFFLINE_DEC23 compress&
[1]     31982004~

没有执行成功，nohup.out 里面就是那条报错信息：

SQL1035N  The operation failed because the specified database cannot be

connected to in the mode requested.  SQLSTATE=57019

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db2 list application 一看，也没有任何application 连接呀。后来又试了db2stop force, db2start 之后再执行。也不行，最后干脆db2_kill，然后db2start，再执行备份。还是报错。

不过不知道我的db2_kill是不是成功了。。因为返回值是这样的。

:/db2backup/WEB_OFFLINE_DEC23] # db2_kill

Application ipclean: Removing DB2 engine and client IPC resources for db2inst1

[:/db2backup/WEB_OFFLINE_DEC23] # db2start

12/24/2015 03:48:28     0   0   SQL1063N  DB2START processing was successful.

高手指教一下呢。虽然最后也成功了。但是为啥我这样都不成功？。试了不下10次。nohup.out里面一直都是那个报错。