1. What is striping in ASM.
ASM striping is the process of dividing a file into 1 MB extents and spreading the extents evenly across all disks in the disk group
Oracle ASM striping has two primary purposes:
· To balance loads across all of the disks in a disk group
· To reduce I/O latency
2. What mirroring in ASM.
ASM provides automatic mirroring of ASM files and allows the mirroring level to be specified by group. This mirroring occurs at the extent level. If a disk group is mirrored, each extent has one or more mirrored copies, and mirrored copies are always kept on different disks in the disk group.
There are three ASM mirroring options:
Normal redundancy (Two-way mirroring) - Each extent has one mirrored copy in this option
High redundancy (Three-way mirroring) - Each extent has two mirrored copies in this option.
External redundancy(Unprotected mirroring) - ASM provides no mirroring in this option, which is used when mirroring is provided by the disk subsystem.
3. Where ASM pfile will be stored?
ASM pfile normally will be located in GRID_HOME/dbs and it contains location of spfile which in ASM disk groups.
5. What are the files we can store in ASM?
we can store CRD files, archivelog files, spfile, rman backup files, flashback logs in ASM
6. What is rebalancing and when it happens.
re-balancing is process of striping, when ever disk is added or removed to ASM diskgroup asm will start rebalancing data accross all disks. if you add disk, rebalancing will take some data from all the disks and store into new disk so that all disks in ASM diskgroup will fill equally.
7. What is power limit and its range from version 11.2.0.4
ASM striping is the process of dividing a file into 1 MB extents and spreading the extents evenly across all disks in the disk group
Oracle ASM striping has two primary purposes:
· To balance loads across all of the disks in a disk group
· To reduce I/O latency
2. What mirroring in ASM.
ASM provides automatic mirroring of ASM files and allows the mirroring level to be specified by group. This mirroring occurs at the extent level. If a disk group is mirrored, each extent has one or more mirrored copies, and mirrored copies are always kept on different disks in the disk group.
There are three ASM mirroring options:
Normal redundancy (Two-way mirroring) - Each extent has one mirrored copy in this option
High redundancy (Three-way mirroring) - Each extent has two mirrored copies in this option.
External redundancy(Unprotected mirroring) - ASM provides no mirroring in this option, which is used when mirroring is provided by the disk subsystem.
3. Where ASM pfile will be stored?
ASM pfile normally will be located in GRID_HOME/dbs and it contains location of spfile which in ASM disk groups.
5. What are the files we can store in ASM?
we can store CRD files, archivelog files, spfile, rman backup files, flashback logs in ASM
6. What is rebalancing and when it happens.
re-balancing is process of striping, when ever disk is added or removed to ASM diskgroup asm will start rebalancing data accross all disks. if you add disk, rebalancing will take some data from all the disks and store into new disk so that all disks in ASM diskgroup will fill equally.
7. What is power limit and its range from version 11.2.0.4
Beginning with Oracle Database 11g Release 2(11.2.0.2), if the COMPATIBLE.ASM disk group attribute is set to 11.2.0.2 or higher, then the range of values is 0 to 1024.
8. How can we know ASM re-balance is going on in ASM instance.
We can use V$ASM_OPERATION view to check re-balance is going on or not. if below query displays any rows, we can say re-balance is in progress.
select * from V$ASM_OPERATION where STATE='RUN';
8. How can we know ASM re-balance is going on in ASM instance.
We can use V$ASM_OPERATION view to check re-balance is going on or not. if below query displays any rows, we can say re-balance is in progress.
select * from V$ASM_OPERATION where STATE='RUN';
9. Can we copy files from ASM to OS file system.
Yes, we can copy files from ASM using cp commands in ASMCMD command prompt.
12. What is Req_mir_free_MB in lsdg output?
13. How to take ASM metadata backup?
Yes, we can copy files from ASM using cp commands in ASMCMD command prompt.
12. What is Req_mir_free_MB in lsdg output?
13. How to take ASM metadata backup?
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