ASM related concepts and instance Creation

1. concepts related to ASM (concept taken from: the world of amasha)

1. What is ASM (Auto Storage Management)

 
1 Automatic Storage Management is a tool used to manage disks.2 Supports striping, mirror data files, and restore files between multiple physical devices.3 Files are evenly distributed across all disks in the disk group according to the allocation unit aus (Allocation units). ASM uses the index technology to track the location of each aus.4 Supports dynamic increase and decrease of online disks. When the disk changes, the aus automatically implements Dynamic Distribution again.5 Supports RAC cluster technology. One ASM instance is run on each node, and point-to-point communication can be achieved between ASM instances.6It is a software-only implementation method. A third-party raid works at the volume level and uses a uniform strip size. ASM can work at the file level and different files can use different strip sizes.
 

2. Advantages of ASM

1 Disk increase: it is very easy to add disks. No downtime is required and the file area is automatically reassigned.2 I/O allocation: I/O is automatically distributed across all available Disks without manual intervention. This reduces the possibility of hot spots.3 Band Width: segments in the redo log file can be subdivided (K for faster transmission rate). For data files, the band width is slightly larger (MB, to transmit a large number of data blocks at a time ).4 Buffer: the ASM file system directly performs input/output without buffering.5 Image: If the hardware image is unavailable, you can easily create a software image.6Core asynchronous I/O: to implement core asynchronous I/O, no special settings are required, and no original or third-party file systems (such as Veritas quick I/O) are required)
 

3. Raid level of common ORACLE data files

1 System and undo tablespaces are usually placed on RAID 1 volumes.2 Online redo logs are usually placed on RAID 0 volumes.3 Control files are usually placed on RAID 0 + 1 volumes.4Data files are usually placed on RAID 5 volumes.
 

4. ASM architecture (mainly composed of an ASM instance and an ASM disk group)

 
1 To use ASM, you need to create an ASM instance for managing the ASM disk group.2 An ASM disk is composed of one or more ASM disks.3 An ASM disk can be an actual disk, a partition of a disk, or a logical volume managed by LVM, but must be an unformatted raw device.4The size of the ASM disk group is the total size of the ASM disk in the group. The available capacity varies depending on the fault tolerance level.
 

5. ASM instance and RDBMS instance

 1  The ASM instance is similar to a common database instance (RDBMS) and also consists of SGA and a bunch of background processes. For most systems, SGA only needs 64 MB.  2   The largepool In the ASM instance is used to store the extent map. The largepool size can be calculated based on the database size. Generally, the size of GB needs to be 1 MB for the extent map.  3   A common RDBMS instance locates a data file and opens its data file. In a database stored in ASM, the job is taken over by the ASM instance, that is, the ASM instance is used to locate and manage the ASM disk, disk group.  4   The ASM instance has background processes similar to common RDBMS instances, such as SMON, pmon, lgwr, dbwr, and ckpt. Two new processes are added: rbal and arbn.  5   Rbal: Used to coordinate and manage the dynamic balance between disk groups  6   Arbn: Multiple arbn can be used to move the AU  7  The ASM instance only locates and manages the ASM disk. It cannot load or open the database, and therefore cannot read the data dictionary information.  8 An ASM instance usually has a parameter. You can only use the password file or operating system authentication as sysdba or sysoper to start or close the instance.

 
1 An ASM instance can provide services for multiple RDBMS instances. Multiple ASM instances can be created on one host, but an ASM instance is usually used on one host.2 If an instance serves multiple RDBMS instances, we recommend that you separate asm_home of ASM from ORACLE_HOME of dB to facilitate future upgrade and maintenance.3Create and configure an ASM disk group after the ASM instance is started.
 

1 The RDBMS instance using the ASM disk is the same as the common RDBMS instance, but there are two more background processes, rbal and ASMB.2 ASMB uses a server process such as Oracle + ASM1 to establish a session between a common RDBMS instance and an ASM instance, and transmits information about disk files.3Note: The ASM instance does not replace the RDBMS instance to read or write data files. Data is transmitted directly on the ASM disk and RDBMS instance. The ASM instance is only used to locate the ASM disk where the data file is located, disk Area and required information. Assuming that a new data file is added, the RDBMS informs the ASM instance to create a data file, the ASM instance allocates a disk area (extent), and creates a disk area ing address and returns it to the RDBMS instance, RDBMS writes data directly to the disk group.
 

6. File Types stored in the ASM instance

 
1 Control File, parameter file, online log file, archived log file, data file, temporary file2RMAN backup set, image copy, control file backup set, DataPump dumping file, change Tracing file
 

Ii. Create an ASM instance (The following is a demonstration based on Vmware + solaris10 + Oracle 10g R2)

1. Add a bare device Solaris 10

2. view the added bare Device

1 -Bash- 3.00 $ CD/dev/ Rdsk  2 -Bash- 3.00 $ Ls -L c2t * D0s1  3 -- RedRawCharacter-based access  4 Lrwxrwxrwx 1 Root 64 APR 14  22 : 29 C2t0d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 0 , 0 : B, Raw   5 Lrwxrwxrwx 1 Root64 APR 14   22 : 29 C2t1d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 1 , 0  : B,Raw 6 Lrwxrwxrwx 1 Root 64 APR 15   01 : 26 C2t2d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 2 ,0  : B,Raw  7 Lrwxrwxrwx 1 Root 64 APR 15   01 : 26 C2t3d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @2 /SD @ 3 , 0  : B,Raw  8 -Bash- 3.00  $  9 -Bash- 3.00 $ CD/dev/ DSK  10 -Bash- 3.00 $ Ls -L c2t * D0s1 11 -- RedBBlock-Based Access  12 Lrwxrwxrwx 1 Root 60 APR 14   22 : 29 C2t0d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad,1976 @ 2 /SD @ 0 , 0  :B  13 Lrwxrwxrwx 1 Root 60 APR 14   22 : 29 C2t1d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad,790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 1 , 0  :B  14 Lrwxrwxrwx 1 Root 60 APR 15   01 : 26 C2t2d0s1-> http://www.cnblogs.com/devices/pci @0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 2 , 0  :B  15 Lrwxrwxrwx 1 Root 60 APR 15   01 : 26 C2t3d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 3 , 0  :B  16 -Bash- 3.00 $

3. Change the bare device Property Group

1 # Chown -R oracle: oinstall/dev/rdsk/c2t * D0s1  2 # Chmod   660 /Dev/rdsk/c2t * D0s1  3 # Ls -L/dev/rdsk/c2t * D0s1  4 Lrwxrwxrwx 1 Root 64 APR14   22 : 29 /Dev/rdsk/c2t0d0s1> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 0 , 0  : B, raw  5 Lrwxrwxrwx 1 Root 64 APR 14   22 : 29 /Dev/rdsk/c2t1d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 1 , 0  : B, raw 6 Lrwxrwxrwx 1 Root 64 APR 15   01 : 26 /Dev/rdsk/c2t2d0s1-> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @ 2 /SD @ 2 ,0  : B, raw  7 Lrwxrwxrwx 1 Root 64 APR 15   01 : 26 /Dev/rdsk/c2t3d0s1> http://www.cnblogs.com/devices/pci @ 0 , 0 /Pci15ad, 790 @ 11 /Pci15ad, 1976 @2 /SD @ 3 , 0 : B, raw

Hmm? Nothing changed! However, this step cannot be omitted. Otherwise, the added disk cannot be identified when you use dbca to add a disk group. If you know this, you can leave a message for me!

4. Set the environment variable: Display

 
1Export display =192.168.2.1:0.0
 

Haha, now we can use xmanager + dbca to install ASM!