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[转] ASM Handling Block Corruptions

Posted by admin on 25th November 2012

Some excellent experiment From Honcho

为了保护disks 上的数据,Oracle ASM 对disk groups 有3种冗余方式:
(1)external redundancy 表示Oracle不帮你管理镜像,功能由外部存储系统实现,比如通过RAID技[......]

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ASM error : DBD ERROR: OCIStmtExecute

Posted by admin on 26th September 2012

问题描述:在Exadata迁移中使用的DG被直接用asmcmd从asm中rm掉了所有datafile.但是最后的一级目录无法删除,并且影响到了其他实例.在rm hang之后 diskgroup无法添加任何文件.原来的实例的所有add datafile drop directory操作均被hang住[......]

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Why ASM?

Posted by admin on 13th June 2012

Why ASM?

. ASM is an Oracle provided Database/Cluster filesystem and Storage Volume manager, optimized for Oracle for any kind of workload (b[......]

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11gR2 rac ora.asm error (ASM)

Posted by admin on 26th April 2012

ASM – ora.asm error

11.2.0.3 RAC CRS 无法启动

[ohasd(25286)]CRS-2112:The OLR service started on node db-41.
2012-04-25 14:46:13.120
[ohasd(25286)]CRS-1301:Oracle High Availability Service started on node db-41.
2012-04-25 14:46:13.120
[ohasd(25286)]CRS-8017:location: /etc/oracle/lastgasp has 2 reboot advisory log files, 0 were announced and 0 errors occurred
2012-04-25 14:46:14.181
[/data/11.2.0/grid/bin/orarootagent.bin(25332)]CRS-5016:Process "/data/11.2.0/grid/bin/acfsload" spawned by agent "/data/11.2.0/grid/bin/orarootagent.bin" for action "check" failed: details at "(:CLSN00010:)" in "/data/11.2.0/grid/log/db-41/agent/ohasd/orarootagent_root/orarootagent_root.log"
2012-04-25 14:46:17.031
[gpnpd(25510)]CRS-2328:GPNPD started on node db-41.
2012-04-25 14:46:20.794
[cssd(25593)]CRS-1713:CSSD daemon is started in clustered mode
2012-04-25 14:46:22.520
[ohasd(25286)]CRS-2767:Resource state recovery not attempted for 'ora.diskmon' as its target state is OFFLINE
2012-04-25 14:46:40.715
[cssd(25593)]CRS-1707:Lease acquisition for node db-41 number 1 completed
2012-04-25 14:46:42.003
[cssd(25593)]CRS-1605:CSSD voting file is online: /dev/mapper/Vote03; details in /data/11.2.0/grid/log/db-41/cssd/ocssd.log.
2012-04-25 14:46:42.008
[cssd(25593)]CRS-1605:CSSD voting file is online: /dev/mapper/Vote02; details in /data/11.2.0/grid/log/db-41/cssd/ocssd.log.
2012-04-25 14:46:42.015
[cssd(25593)]CRS-1605:CSSD voting file is online: /dev/mapper/Vote01; details in /data/11.2.0/grid/log/db-41/cssd/ocssd.log.
2012-04-25 14:46:52.173
[cssd(25593)]CRS-1601:CSSD Reconfiguration complete. Active nodes are db-41 .
2012-04-25 14:46:54.177
[ctssd(25738)]CRS-2407:The new Cluster Time Synchronization Service reference node is host db-41.
2012-04-25 14:46:54.177
[ctssd(25738)]CRS-2401:The Cluster Time Synchronization Service started on host db-41.
[client(25843)]CRS-10001:25-Apr-12 14:46 ACFS-9391: Checking for existing ADVM/ACFS installation.
[client(25848)]CRS-10001:25-Apr-12 14:46 ACFS-9392: Validating ADVM/ACFS installation files for operating system.
[client(25850)]CRS-10001:25-Apr-12 14:46 ACFS-9393: Verifying ASM Administrator setup.
[client(25853)]CRS-10001:25-Apr-12 14:46 ACFS-9308: Loading installed ADVM/ACFS drivers.
[client(25856)]CRS-10001:25-Apr-12 14:46 ACFS-9154: Loading 'oracleoks.ko' driver.
[client(25913)]CRS-10001:25-Apr-12 14:46 ACFS-9154: Loading 'oracleadvm.ko' driver.
[client(25974)]CRS-10001:25-Apr-12 14:46 ACFS-9154: Loading 'oracleacfs.ko' driver.
[client(26099)]CRS-10001:25-Apr-12 14:46 ACFS-9327: Verifying ADVM/ACFS devices.
[client(26103)]CRS-10001:25-Apr-12 14:46 ACFS-9156: Detecting control device '/dev/asm/.asm_ctl_spec'.
[client(26107)]CRS-10001:25-Apr-12 14:46 ACFS-9156: Detecting control device '/dev/ofsctl'.
[client(26113)]CRS-10001:25-Apr-12 14:46 ACFS-9322: completed
2012-04-25 14:47:06.975
[ohasd(25286)]CRS-2807:Resource 'ora.asm' failed to start automatically.

[ctssd(25738)]CRS-2405:The Cluster Time Synchronization Service on host db-41 is shutdown by user
2012-04-25 14:51:25.852
[/data/11.2.0/grid/bin/orarootagent.bin(25523)]CRS-5016:Process "/data/11.2.0/grid/bin/acfsload" spawned by agent "/data/11.2.0/grid/bin/orarootagent.bin" for action "check" failed: details at "(:CLSN00010:)" in "/data/11.2.0/grid/log/db-41/agent/ohasd/orarootagent_root/orarootagent_root.log"
2012-04-25 14:51:35.716
[cssd(25593)]CRS-1603:CSSD on node db-41 shutdown by user.
2012-04-25 14:51:35.725
[ohasd(25286)]CRS-2767:Resource state recovery not attempted for 'ora.cssdmonitor' as its target state is OFFLINE
2012-04-25 14:51:36.224
[cssd(25593)]CRS-1660:The CSS daemon shutdown has completed
2012-04-25 14:51:38.144
[gpnpd(25510)]CRS-2329:GPNPD on node db-41 shutdown.

重建spfile :

+ASM.asm_diskgroups='DATA','ARCH'
*.
asm_diskstring='/dev/mapper/*'
*.
asm_power_limit=1
*.
diagnostic_dest='/data/app/oracle'
*.
instance_type='asm'
*.
large_pool_size=12M
#*.local_listener='LISTENER_+ASM'
*.
remote_login_passwordfile='EXCLUSIVE'
 
 
egpfile 拉起  ASM instance mount data group
 
SQL>create spfile='+DATA' from pfile='xxx';

[grid@db-41 ~]$ sqlplus ‘/as sysa[......]

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ASM Preferred mirror Read

Posted by admin on 25th April 2012

ASM Preferred mirror Read

Introduction

The concept of the Preferred Read is not a new idea, but is now implemented in Oracle’s ASM volume 
management in Oracle 11g.The concept is to read from the storage that can present the needed data at a lower
latency.  Initially, this was designed for WAN or site-specific storage in order to avoid higher-latency site
connections. By restricting data reads to the local storage, the application would be able to service requests at
nominal read speeds while writes were the only communication needed to traverse the long haul site link. This is
a feature that is available to most Operating Systems with their included volume manager and as a feature to
Symantec/Veritas through the title Preferred Plex. This paper will discuss the merits of using PRG technology with Oracle ASM

eg:


SELECT name, failgroup FROM v$asm_disk;

NAME                           FAILGROUP
------------------------------ ------------------------------
DATA_0000                      DATA_0000
DATA_0001                      DATA_0001
DATA_0002                      DATA_0002

3 rows selected.

SQL> ALTER SYSTEM SET ASM_PREFERRED_READ_FAILURE_GROUPS = 'data.data_0000', 'data.data_0001', 'data.data_0002';
Allocating ASM Extent Sets
With ASM redundancy, the first file extent allocated is chosen as primary extent, and
the mirrored extent is called the secondary extent. In the case of high redundancy,
there will two secondary extents. This logical grouping of primary and secondary
extents is called an extent set. When a block is read from disk, it is always read from
the primary extent, unless the primary extent cannot be read. In Oracle Database
11g, the preferred read feature allows the database to read the secondary extent first
instead of reading the primary extent. This is especially important for RAC Extended
Cluster implementations.
As stated earlier, ASM in Oracle Database 10g always reads the primary copy of a mirrored extent set. Thus, a read for a specific block may require a read of the primary extent at the remote site across the interconnect. Accessing a remote disk through a metropolitan area or wide area storage network is substantially slower than accessing a local disk. This can tax the interconnect as well as result in high I/ O and network latency. To assuage this, Oracle Database 11g provides a feature called preferred reads. This feature enables ASM administrators to specify a failure group for local reads–– that is, provide preferred reads. In a normal or high-redundancy diskgroup, when a secondary extent is on a preferred disk and the primary extent is remote, the secondary extent is read rather than the primary one on that node. This feature is especially beneficial for extended cluster configurations.

根据上面所说的 “This is especially important f[......]

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Why ASMLIB and why not?

Posted by admin on 19th October 2011

ASMLIB是一种基于Linux module,专门为Oracle Automatic Storage Management特性设计的内核支持库
(kernel support library)。
长久以来我们对ASMLIB的认识并不全面,这里我们来具体了解一下使用ASMLIB的优缺点。[......]

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Posted in Oracle Experience | 2 Comments »