Re: ASM extent and RAC process doubt

From: <>
Date: Mon, 18 Aug 2008 21:03:35 +0200
Message-ID: <>

On Mon, 18 Aug 2008 11:12:34 -0700 (PDT), "" <> wrote:

>Hi All,
>10g R2 on Oracle EL 4.0
>I am junior DBA and trying to learning stuff from documentation and
>implementing stuff on test machines.
>I have 2 doubts whcih I could not find on net -
>While going through documentation for ASM, It is clearly mentioned
>that whatever datafile we would
>create on ASM diskgroup will have 1 mb extent and it would be striped
>over all the disks available in the diskgroup - ( Just assuming
>external redu.. . )
>I have database and only using ASM, if we have a Table which got it's
>extents more than 1 mb ( in LMT after some time extents size would be
>1m .. 8m... and so on ..)
>Then does that mean in dba_extents it is showing you as a single 8mb
>extents but in reality it is spreaded over 8 diff. extents on diff.
>disks which are associated in diskgroup . ?? ??

Whatever organisation the database is, an extent is still made up of database blocks. This is the smallest unit. A database block potentially can consist of multiple disk blocks.

You shouldn't worry about ASM. Think of ASM as Oracle's volume manager.
Would you ask the same question about the Linux volume manager or whatever Unix volume manager?
I don't think so.

Sybrand Bakker
Senior Oracle DBA
Received on Mon Aug 18 2008 - 14:03:35 CDT

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