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1 Reply Latest reply: Jan 17, 2013 12:15 AM by SalmanQureshi RSS

ASM Questions

user8930326 Newbie
Currently Being Moderated
Hi Experts ...

I am new to this RAC ...

Normally on a Linux machine if we wish to deploy 4 Databases { either single or RAC } then how many Disks needs to be create by SA.

Will there be any formula. or standard best practice [ ours is RHEL 6 ]

also please share the query to find the un-used ASM disks ...

This is what I used and i see
select header_status "Header"
, mode_status "Mode"
, path "Path"
, lpad(round(os_mb/1024),7)||'Gb' "Disk Size"
from v$asm_disk
where header_status in ('FORMER','CANDIDATE');


this show my disks as /dev/oracleasm/disks with multiple lines ... but never displays the read disk name

this is my disks info
/dev/oracleasm/disks/ASM_01
/dev/oracleasm/disks/ASM_02
/dev/oracleasm/disks/ASM_03

Of them first 2 are used by one disk group. The other one is not used ... but never diskplayed on the above query.

Please provide any help ... asuming you will provide ... the commands that a DBA can execute.

Appreciate your help.

Edited by: user8930326 on Jan 16, 2013 7:07 PM
  • 1. Re: ASM Questions
    SalmanQureshi Expert
    Currently Being Moderated
    Normally on a Linux machine if we wish to deploy 4 Databases { either single or RAC } then how many Disks needs to be create by SA.
    There isn't any thing mandatory, it is up to you. You can create a single very large diskgroup and put all databases on the diskgroup. Now this diskgroup can have as many physical disks as you want with either external redundancy (mirroring at OS/hardware level) or normal/high redundency.
    Will there be any formula. or standard best practice [ ours is RHEL 6 ]
    No
    also please share the query to find the un-used ASM disks ...
    What do you mean by unused ASM disks? All disks in an AMS diskgroup are used because Oracle will spread data across all the disks in this diskgroup.
    this show my disks as /dev/oracleasm/disks with multiple lines ... but never displays the read disk name
    It shows you on multiple linse because you have not formated your SQL output on SQLPLUS. set columns format as follows for the columns you want to display from v$asm_disk

    set lines 2000
    col path format 140


    See form documentation what are the columns of v$asm and choose whatever column you want to display for each disk
    http://docs.oracle.com/cd/E14072_01/server.112/e10820/dynviews_1022.htm
    select header_status "Header"
    , mode_status "Mode"
    , path "Path"
    , lpad(round(os_mb/1024),7)||'Gb' "Disk Size"
    ,total_mb/1024 
    ,free_mb
    , group_number
    from v$asm_disk
    Salman

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