1. What are the init parameters related to ASM?
INSTANCE_TYPE = ASM
ASM_POWER_LIMIT = 11
ASM_DISKSTRING = '/dev/rdsk/*s2', '/dev/rdsk/c1*'
ASM_DISKGROUPS = DG_DATA, DG_FRA
2. What is rebalancing (or) what is the use of ASM_POWER_LIMIT?
ASM_POWER_LIMIT is dynamic parameter, which will be useful for rebalancing the data across disks.Value can be 1(lowest) to 11 (highest).
3. What processes does the rebalancing?
RBAL, ARBn
4. Describe about ASM architecture.
ASM stands for Automatic Storage Management,Instance that manages the diskgroup metadata
Disk Groups
Logcal grouping of disks
Determines file mirroring options
ASM Disks
LUNs presented to ASM
ASM Files
Files that are stored in ASM disk groups are called ASM files, this includes database files
Notes:
Many databases can connect as clients to single ASM instances
ASM instance name should only be +ASM only
One diskgroup can serve many databases
5. what are the Types of Redundancies ?
External redundancy :
Does not have Fail group,so there is no mirroring.
Normal redundancy :
Provides a 2 - way mirroring of all extends in the disk group,which result in 2 Fail Group.
High redundancy :
Provides a 3 - way mirroring of all extends in the disk group,which result in 3 Fail Group.
6. What are the ASM Background Processes ?
RBAL – Oracle background process. In an ASM instance coordinated rebalancing operations. In a DB instance, opens and mount diskgroups from the local ASM instance.ARBx – Oracle backgroud processes. In an ASM instance, a slave for rebalancing operationsPSPx – Oracle backgroud processes. In an ASM instance, Process SpawnersGMON – Oracle backgroud processes. In an ASM instance, diskgroup monitor.ASMB – Oracle background process. In an DB instance, keeps a (bequeath) persistent DB connection to the local ASM instance. Provides heart-beat and ASM statistics. During a diskgroups rebalancing operation ASM communicates to the DB AU changes via this connection.O00x – Oracle backgroud processes. Slaves used to connected from the DB to the ASM instance for ‘short operations’.
7. How to add/remove disk to/from diskgroup?
ALTER DISKGROUP data1 ADD DISK '/devices/diska5';
ALTER DISKGROUP disk_group_1 DROP DISK diska2;
8. How to copy file to/from ASM from/to filesystem?
By using ASMCMD cp command
9. How to find out the databases, which are using the ASM instance?
ASMCMD> lsct
SQL> select DB_NAME from V$ASM_CLIENT;
10. What are different types of stripings in ASM & their differences?
Fine-grained striping
Coarse-grained striping
11. Can my RDBMS and ASM instances run different versions?
Yes. ASM can be at a higher version or at lower version than its client databases. There’s two
components of compatiblity:
Software compatibility
Diskgroup compatibility attributes:
compatible.asm
compatible.rdbms
12. How do I backup my ASM instance?
Not applicable! ASM has no files to backup
13. Where do I run my database listener from; i.e., ASM HOME or DB HOME?
It is recommended to run the listener from the ASM HOME. This is particularly important for RAC env, since the listener is a node-level resource. In this config, you can create additional [user] listeners from the database homes as needed.
14. How do I backup my ASM instance?
Not applicable! ASM has no files to backup, as its does not contain controlfile,redo logs etc.
15. Why Oracle recommends two diskgroups?
Oracle recommends two diskgroups to provide a balance of manageability, utilization, and performance.
16. What are the ACFS Features ?
Provides filesystem snapshots (FCOW)
• File system integrity and fast recovery via ACFS metadata checksums and journaling.
• ACFS designed as a peer to peer, multi-node, shared file system model and delivers coherent data access
• ACFS file system is installed as a dynamically loadable OS VFS driver
• Starting with RHEL5, Redhat now supports a ‘white list’ -kernel APIs which they commit they will not change in updates or patches. APIs used by ACFS-ADVM were added to their ‘white list’.
• Customers should be able to install an update or patch to the kernel and our drivers should not be impacted
17. Is ACFS supported on other platforms besides Linux ?
Yes. Other platforms are forthcoming
18. Can ACFS be used to store database datafiles? What about archive logs?
No. Currently we will not support database file to bestored in ACFS. This is due to performance reasons. Though you can do this in test/Q&A environments where performance is not essential
19. Can I sue ACFS to store BFILE data or other non-database related data ?
Yes. ACFS is POSIX compliant filesystem, and thus can store any file data type (besides database files
20. What is Failure groups ?
They are defined within a disk group to support the required level of redundancy. For two-way mirroring you would expect a disk group to contain two failure groups so individual files are written to two locations.
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