ORACLE AUTOMATIC STORAGE Management Translator-Chapter II ASM instance (1)

Chapter II ASM INSTANCEthe type of ASM, for example, can be:The Oracle instance type adds an ASM category after 10g. The parameter instance_type=asm is set.
ASM Instance startup command: Startup  NomountLaunches the instance and background processes. But the disk group is not mounted Mountlater. The instance launches the Asm_diskgroups specified disk group in the parameter file, assuming that the null parameter will trigger the ORA-15110 error message.

ASM 11G has introduced restricted boot parameters for the Mount command. Exclusive launch of asm_diskgroups specified disk group, restricting RDBMS access to disk groups. The restricted command is particularly useful when maintaining disk groups or rebalance. Note: resticted can mount disk groups at the disk group level. Rather than the instance level. The advantage is that it provides fine-grained limits. Such as:

Alter DiskGroup data Mount Restricted;select name,state from V$asm_diskgroup;name State----- ------------------------------------DATA RESTRICTED

Background processes: ASM background processes start with asm_, just as the RDBMS begins with Ora_.

11g ASM Background Process Introduction

ARBX These is the slave processes that does the rebalance activity (where x is a number). Ckptthe Ckptprocess manages Cross-instance calls (in RAC). DBWR This process manages the SGA buffer cache in the ASM instance. DBW Rwrites out dirty buffers (changed metadata buffers) from the ASM Buffer cache to disk. Gmon This process was responsible for managing the disk-level activities (Drop/offline) and advancing diskgroup compatibility. KATE The Konductor or ASM temporary errands (KATE) process is used To process disks online. This process runs in the ASM instance and is started A offlined disk is onlined. LGWRThe lgwrprocess maintains the ASM Active change Directory (ACD) buffers from the ASM instance and flushes ACD change records to Disk. MARK The Mark Allocation Unit (AU) for Resync Koordinator (Mark) Process coordinates the updates to the staleness Registry when the disks go Offline. This process runs in the RDBMS instance and was started only when Disks go offline in ASM redundancy diskgroups. PINGThe pingprocess measures network latency and has the same Functionality in RDBMS instances. Pmon This manages processes and process death in the ASM instance. PSP0 This process Spawner process was responsible for creating and Managing other Oracle processes. pz9x These processes is parallel slave processes (where XIs a number), Used in fetching data on behalf of Gv$queries. Rbal This opens all device files as part of discovery and coordinates the Rebalance activity. Smon This process is the System Monitor and also acts as a liaison to the Cluster synchronization Services (CSS) process (in Oracle clusterware) for Node monitoring. Vktm This are used to maintain the fast timer and have the same Functionality in the RDBMS instances.

ASM SGA and Parameters setting ASM start-up requires very few parameters. The parameter file can be pfile or spfile

*.instance_type=asm *.asm_diskgroups=data,flash *.processes=100 Note that asm_diskstring is site-specific and platform specific *.asm_diskstring= '/DEV/RDSK/C3T19D*S4 '--note assuming that the ASM disk group is manually added forget to update this number, or the missing disk groups will not be able to take their own initiative after reboot. *.remote_login_passwordfile= ' SHARED ' ****** **for 11g use is only the diagnostics directory. *.diagnostic_dest= '/opt/app/admin/+asm/diag '--11g's diagnostic_dest instead of the 10g bdump,cdump,udump is obviously a lot easier to introduce. ******* **for 10g use of the standard dump locations *.background_dump_dest= '/opt/app/admin/+asm/bdump ' *.core_dump_dest= '/opt/app/admin/+asm/cdump ' *.user_dump_dest= '/opt/app/admin/+asm/udump ' *******

Background_dump_dest,core_dump_dest, and user_dump_dest These three parameters have been deprecated in 11g. Do not configure these three parameters in an ASM instance.

Assuming that diagnostic_dest is not configured, the default location is $oracle_base/diag such as the following folder structure will be created: $ORACLE _base/diag/<instance type>/<db_ Unique_name>/<oracle_sid>

Sql> SELECT NAME, VALUE from V$diag_info NAME VALUE ---------- --------------- Diag Enabled TRUE ADR base/u01/app/oracle ADR HOME/U01/APP/ORACLE/DIAG/ASM/+ASM/+ASM1 Diag Trace/u01/app/oracle/diag/asm/+asm/+asm1/trace Diag Alert/u01/app/oracle/diag/asm/+asm/+asm1/alert Diag incident/u01/app/oracle/diag/asm/+asm/+asm1/incident Diag Cdump/u01/app/oracle/diag/asm/+asm/+asm1/cdump Health MONITOR/U01/APP/ORACLE/DIAG/ASM/+ASM/+ASM1/HM Default Trace File

All diagnostic information in 11g can be managed using ADRCI.

Best Practice ASM Parameters

ASM in 11g can use the AMM feature to configure Memory_target and Memory_max_target in Init.ora, and the same two parameters as an RDBMS enable memory to be managed proactively. However, because ASM memory usage is stable. Oracle best practice is to not set these two parameters, using 256M by default, and this configuration conforms to most environments. Note: ASM's use of default parameters in a production environment can cause 4031 errors at ASM instance level, which is inconsistent with best practices, with at least 1G of memory allocated based on the MOS document recommendation. Oracle's best practices are not necessarily reliable. But it can be taken as an examination.

Suppose there is a need to manually adjust the memory, only need to change memory_target can be the alter system set memeory_target=300m;
Of course, suppose you want to disable AMM to set the Memroy_target to 0. But shared_pool,large_pool,db_cache_size these three parameters need to be configured.

db_cache_size This value determines the size of the buffer cache, which is used to cache ASM metadata blocks. The Db_cache_sizeis based on A metadata block size of 4K. This block size is the buffer page size of the Cached metadata and have no bearing or impact on the database block size. Db_cache_size is used to cache metadata block, which is based on metadata block size and 4K. Not affected by the DB block size. Shared_pool This was used for the standard memory usage (Control structures And so on) to manage the instance. The value is also used to store open file Extent maps. Shared_pool is used to store data structures for managing instances. Assume control structures and so on. Also stored at the same time Extent maps and so on. Large_poolThe large_poolvalue is used for LARGE page allocations. PROCESSES This ASM Init.ora parameter limits the number of processes That can-start in ASM instance. Need to modify this parameter from Its default setting for Oracle Database 10gASM instances. The following Recommendation pertains to Oracle Database 10.1.0.3 through 10.2.xand Would work for RAC and Non-rac systems: Processes = 25 + (10 + [max number of concurrent database file Creations, and file extend operations possible]) *n The processes configuration can be calculated based on the formula above. Formula Description: where n is the number of the RDBMS instance (ASM clients) connecting to ASM The source of concurrent file Creations can be any of the following: Several Concurrent CREATE Tablespacecommands Creation of a partitioned table with several tablespace creations RMAN Backup Channels Concurrent Archive log File Creations max number of concurrent database file creations: capable of being the create tablespace concurrency. Number of table spaces involved in creating partitioned tables, number of channels allocated by Rman Backup, number of concurrent creation archives

In 10g, ASM has no AMM characteristics, general configuration such as the following:

Shared_pool_size:128mb Large_pool:12mb Db_cache_size:64mb

We can use Sqlplus to manage ASM like a database: Sql>show SGA However, it is important to note that most RDBMS references do not apply to ASM instances. such as controlfile_files when you try to set this parameter you will receive an error Ora-15021:parameter "Control_files" is not valid in ASM instance
Note the number of references:sql> SHOW PARAMETER CONTROL
NAME TYPE VALUE
-----------------------------------------------------------------------control_files string/opt/oracle/app/ product/10gr2/
Dbs/cntrl+asm.dbf
But in the operating system you can not find this parameter, the parameters of the internal default value for ASM is not meaningful
Two files stored under $oracle_home/dbs: ab_<asm sid>.dat This file is generated when ASM power is started. At the same time, when a DB instance connects to an ASM instance, it gets the environment information, assuming that the file is deleted and the RDBMS cannot communicate with the ASM instance.

Hc_<sid>.dat EM uses this file for monitoring and monitoring of instances.

Assuming that the file is removed, the health check results will be wrong.
asm. dat files do not have a performance impact on ASM, and the files contain only connection information and are required to communicate with ASM instances.

Note that there may be times when you need to set an implied parameter. To assist in diagnosing problems, such as: Diagnostic parameters _disable_instance_parms_check (this number does not need to be 11g)
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ORACLE AUTOMATIC STORAGE Management Translator-Chapter II ASM instance (1)