Re: database activity when mounted

  • From: Jozsef Horvath <horvathjozsef@xxxxxxxxx>
  • To: Josh.Collier@xxxxxxxxxxxx
  • Date: Thu, 4 Nov 2010 16:33:44 +0000

Hi Josh,

I am probably not the only one who is wondering why would you want to "pull
out" any device under the running instance, even it is in mounted state?
I appreciate that I am not aware of you business needs but maybe if you
could share more information about your environment, the requirements then
you may have receive more, constructive response.

The way I see it: if I do need to do any maintenance work on the server
where there is/are oracle instance(s) I make sure it can be done while the
instance is up&running. I case it is not possible and the SLA allows
downtime then I shut the database down beforehand do the maintenance work.
Though, it makes me thinking that if your instance is in "only" mounted
state what could prevent you to shut it down properly then unmount the FS
underneath? I suppose it is not a standby instance otherwise you would
anticipate activities on the volumes.
Again, important information may be missing here.

Regards,
Jozsef

On 4 November 2010 16:19, Josh Collier <Josh.Collier@xxxxxxxxxxxx> wrote:

>  No responses.
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> I have not tried an os trace. That is a good idea.
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> Let me ask you this.
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> Do you know of any other way besides fuser to detect activity on a volume?
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> *From:* Hemant Chitale [mailto:hemantkchitale@xxxxxxxxx]
> *Sent:* Thursday, November 04, 2010 1:38 AM
> *To:* Josh Collier
> *Cc:* ORACLE-L
> *Subject:* Re: database activity when mounted
>
>
>
> Did you get any responses?   Have you done an OS trace of DBWR?
>
> Hemant K Chitale
> http://hemantoracledba.blogspot.com
> sent from my smartphone
>
> On Nov 2, 2010 6:48 AM, "Josh Collier" <Josh.Collier@xxxxxxxxxxxx> wrote:
>
> I have a question for you.
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> What would cause activity on a filesystem that contains only datafiles when
> the database is mounted?
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> My database is segregated so that control and redo files are isolated from
> datafiles and tempfiles.
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> Normally what I expect is this
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> 1.       Database is in mounted state
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> 2.       Ckpt process is active on the mount that contains the control
> files
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> 3.       Lgwr process is active on the mount that contains the redo logs
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> 4.       Dbw0 process is active on the mount that contains the control and
> redo logs.
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> Fuser –cu shows this activity.
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> However, very rapidly the dwb0 process will appear in the mounts that
> contain only datafiles. This is messing me up as I am trying to unmount
> them.   I have been running the fuser every 2 seconds to a log and capture
> the DWB0 process doing something on these mounts. The tool I am using
> expects these devices to be able to be unmounted.
>
>

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