2012年10月24日 星期三
2012年10月16日 星期二
Oracle VM - OVMAPI_4010E Attempt to send command: discover_server to server: 192.168.xxx.xxx failed.
[Error Message on VM Manager Console]
OVMAPI_4010E Attempt to send command: discover_server to server: 192.168.xxx.xxx failed.
[/var/log/ovs-agent.log on VM Server]
[2012-10-15 15:05:21 2478] DEBUG (OVSCommons:124) discover_server: ()
[2012-10-15 15:05:21 2478] ERROR (OVSCommons:143) catch_error: rpmdb open failed
Traceback (most recent call last):
File "/opt/ovs-agent-3.0/OVSCommons.py", line 141, in wrapper
return func(*args)
File "/opt/ovs-agent-3.0/OVSDiscoverServer.py", line 129, in discover_server
pkgs = host.list_package('ovs-agent')
File "/opt/ovs-agent-3.0/host.py", line 235, in list_package
mi = ts.dbMatch("name", name)
TypeError: rpmdb open failed
這時就是VM Server端的rpmdb出了問題，用下列方式run一遍，重建rpmdb後，再到VM manager的console做rediscover即可解決。
# tar cvzf rpmdb-backup.tar.gz /var/lib/rpm
# rm /var/lib/rpm/__db.00*
# rpm --rebuilddb
# rpm -qa | sort ---> # to make sure everything's okay
2012年10月9日 星期二
Oracle DB Basis - Authentication and SQL LOADER
Authentication
OS authentication
- 設定方式: In parameter file, remote_login_passwordfile = none
Use a password file
remote_login_passwordfile = exclusive
- 用orapwd程式，來建立password file
- 如果是用dbca來建立database的，則系統會自動建立password file
SQL Loader
sqlldr system/second3@second3 control=first_tbl.ctl log=first_tbl.log
Segment Space Management
Automatic segment space management (ASSM, or bitmap freelists)
is a simpler and more efficient way of managing space within a
segment. It completely eliminates any need to specify and tune the
pctused, freelists, and freelist groups storage
parameters for schema objects created in the tablespace. If any of
these attributes are specified, they are ignored.
Oracle Database - Data Guard 搭配 Flashback Database
Primary Database: DGTEST_P
使用高性能Disk Array，速度快，價格貴，但空間較小。
Standby Database: DGTEST_S with Real-time Query
使用一般Disk Array，速度慢，價格低，但空間很大。
這時候可以考慮在 DGTEST_S上面 Enable Flashback Database，好處是:
- 如果在 primary database上面發生任何錯誤性的 DDL or DML，同時間也apply到standby database去了，這時可以透過flashback database快速返回某一個時間點，然後開啟switchover將primary and standby互換角色。
- Flashback logs是存放在 standby database server，不會占用到primary database server的硬碟空間。
- 另外一個應用是，如果想要查某個時間點的資料，也可以透過flashbask standby database來達成。
- select standby_became_primary_scn from v$database; flashback database to scn <scn>; alter database convet to physical standby;
Primary Database:
Standby Database:
Oracle VM - Physical Based Devices 高效能I/O
使用VM，又想要高效能的disk I/O，譬如作為database server來使用，可以使用 physical based devices。
第1顆硬碟是Virtual Disk，安裝OS和Oracle Software。
第2顆硬碟是Physical Disk，可以直接對應到FC disk arrary的LUN or SSD。
接下來就可以在作業系統看到此顆硬碟，做LVM。
用DD實際測試I/O，效能還不賴，有456 MB/s。
第1顆硬碟是Virtual Disk，安裝OS和Oracle Software。
第2顆硬碟是Physical Disk，可以直接對應到FC disk arrary的LUN or SSD。
接下來就可以在作業系統看到此顆硬碟，做LVM。
用DD實際測試I/O，效能還不賴，有456 MB/s。
Oracle Database - Automatic Memory Management
Automatic Memory Management
When Automatic Memory Management is enabled, the database will automatically set the optimal distribution of memory. The distribution of memory will change from time to time to accomodate changes in the workload.
Automatic Memory Management has been successfully enabled. The Memory sizes will be adjusted automatically by the database to achieve optimal distribution. The distribution of memory will change from time to time to accomodate changes in the workload.
- Total Memory Size
- Maximum Memory Size
可以看到SGA參數會自動調整
PGA參數也是自動調整
當Automatic Memory Management is disabled，就可以去調整
- Total SGA Size
- Maximum SGA Size
- 調整 Aggregate PGA Target
如何手動開關 Automatic Memory Management ?
--關 Automatic Memory Management
ALTER SYSTEM SET memory_target='0' SCOPE=BOTH;
ALTER SYSTEM SET sga_max_size = 786432000 SCOPE=SPFILE;
ALTER SYSTEM SET sga_target = 524288000 SCOPE=BOTH;
延伸閱讀: 如何完整關閉 AMM (Automatic Memory Management)
--開 Automatic Memory Management
ALTER SYSTEM SET memory_target='805306368' SCOPE=BOTH;
ALTER SYSTEM SET sga_target='0' SCOPE=BOTH;
ALTER SYSTEM SET pga_aggregate_target='0' SCOPE=BOTH;
延伸閱讀: 如果不小心設了sga_max_size，如何完整啟動 Automatic Memory Management
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