Re: doubt about ASM

Jagjeet Singh wrote:
> Hi All,
>
> I have some doubts about ASM.
>
> I have installked ASM on my linux box and created two databases which
> are totaly using ASM. I created controlfile on local file system only.
>
> 1. Suppose I want to remove my one database. I just shut abort the
> database and remove the controlfile. Now I need to remove all files
> belong to DB_1 from ASM.
>
> I am using one single Diskgroup for both Databases. So, can not drop
> Diskgroup. Now, How can I identify files of DB_1 database ?

You don't remove databases this way with ASM (or with OMF files residing on file systems.) You simply

DROP DATABASE; and all OMFs (Oracle-Managed Files) are deleted automatically (except for special files on raw devices,) including control files and spfile. Archived logs and backups can then be removed using RMAN. You can also use ASMCMD tool to locate and remove dangling data files on ASM diskgroups.

> 2. If I create a normal redundancy diskgroup using two failgroup. It
> shows me total_mb and free_mb space as available. Whenever
> my database takes 1 extent of 100mb it reduces 200mb from
> free_mb column which is also understandable.
>
> But I am not able to figureout about col required_mirror_free_mb. What
> it is saying. I have read oracle documentation but still not able to understand.
>

This shows how much free space there should be in a disk group so that ASM could rebalance the group after disk failure with required redundancy for all files. Related USABLE_FILE_MB shows how much space you can occupy without compromising redundancy in case of disk failure. If free space falls below required_mirror_free_mb and a disk in the disk group fails, ASM will be unable to rebalance the disk group to restore required redundancy and some files will receive "reduced redundancy" status, that is they will have extents that have less mirrors than required by the diskgroup redundancy settings (in case of external redundancy, this means that some extents are missing.) V$ASM_FILE.REDUNDANCY_LOWERED='Y' will show you files with reduced redundancy.

Hth,

    Vladimir M. Zakharychev
    N-Networks, makers of Dynamic PSP(tm)     http://www.dynamicpsp.com Received on Sun May 07 2006 - 11:50:55 CDT