Thanks.
--
Alan Davey
adavey_at_competitrack.com
212-604-0200 x106
On 8/7/2002 6:16 PM, Gogala, Mladen <MGogala_at_oxhp.com> wrote:
>I believe that oracle sets the status of the particular member in
>
>v$logfile table to 'UNUSABLE' and that it archives only the usable
>
>member. Cary has mentioned that LGWR does actually read the file
>to
>ensure consistency, so I don't believe that a corrupt file will be
>
>archived.
>
>Mladen Gogala
>Oracle DBA
>Phone: (203) 459-6855
>Email: mgogala_at_oxhp.com
>
>
>
>> -----Original Message-----
>> From: Alan Davey [mailto:adavey_at_competitrack.com]
>> Sent: Wednesday, August 07, 2002 12:50 PM
>> To: Multiple recipients of list ORACLE-L
>> Subject: Re: duplexing redos and archives
>>
>>
>> Dan,
>>
>> So in your scenario, what happens when Oracle goes to archive
>> the redo logs? Does it first compare the duplexed versions,
>> or does it just archive the first (corrupted) file in the group?
>>
>> Regards,
>> --
>>
>> Alan Davey
>> adavey_at_competitrack.com
>> 212-604-0200 x106
>>
>>
>> On 8/7/2002 11:54 AM, Fink, Dan <Dan.Fink_at_mdx.com> wrote:
>> >Joe,
>> > #2 could result from the processes/hardware path
>> outside of Oracle's
>> >control. For example, the redo logs are written to disks
>> with separate
>> >caches. Disk #1 cache soft corrupts the data being stored, but
>it
>> >is not
>> >caught by the system. Disk#2 cache writes it correctly. The key
>is
>> >that
>> >Oracle 'thinks' the log has been written correctly when it was
>not.
>> >I'm not
>> >a hardware/systems expert, but the scenario of one file
>> being corrupted
>> >where another is not sounds possible, but unlikely. Then again...why
>
>> >take
>> >the chance.
>> >
>> >
>> >-----Original Message-----
>> >Sent: Wednesday, August 07, 2002 6:53 AM
>> >To: Multiple recipients of list ORACLE-L
>> >
>> >
>> >Dan,
>> >
>> >If scenario #2 happened wouldn't both sets of logs be corrupted
>since
>> >oracle is writing the same thing to both files?
>> >
>> >BTW, from the tone of everyone responding I think I'll push for
>> >continuing to duplex. Thanks.
>> >
>> >Joe
>> >
>> >"Fink, Dan" wrote:
>> >>
>> >> This may be 'old school' thinking, but I prefer to duplex my
>redo
>> >logs.
>> >Why?
>> >> Because there are some things that mirroring cannot protect
>you
>> >against.
>> >> 1. The deletion of a redo log through human error (been there,
>
>> >recovered
>> >> from it...)
>> >> 2. The logical corruption of a redo log (never experienced
>> it myself,
>> >but
>> >it
>> >> is theortically possible)
>> >> 3. Oracle's fault tolerance regarding the ability to function
>as
>> >long as 1
>> >> redo log in a group is accessible
>> >>
>> >> Considering the critical nature of the redo logs (lose one and
>
>> >your
>> >recovery
>> >> is done...and perhaps your job) and their small size in relation
>
>> >to
>> >overall
>> >> databse size, duplexing in a group makes sense.
>> >>
>> >> This is one of those issues where valid arguements exist on
>both
>> >sides. In
>> >> some ways, the logical arguements are on the side of not duplexing
>
>> >redo
>> >logs
>> >> that are mirrored. However, when you consider that the loss
>or
>> >corruption
>> >of
>> >> a single redo log can cause the database to be unrecoverable
>is
>> >enough to
>> >> justify the cost of duplexing.
>> >>
>> >> Just my humble (old school) opinion
>> >>
>> >> Dan Fink
>> >>
>> >> -----Original Message-----
>> >> Sent: Tuesday, August 06, 2002 12:13 PM
>> >> To: Multiple recipients of list ORACLE-L
>> >>
>> >> Currently we are duplexing our redo logs and archive logs through
>> >> oracle. We do this at the oracle level because we are
>> using mirroring
>> >> (raid0?) and if we lose a redo log or archive file the database
>
>> >will not
>> >> be affected.
>> >>
>> >> We will be moving to raid5 arrays in the future and are wondering
>> >> whether we still need to do the duplexing. Since the arrays
>are
>> >made up
>> >> of data disks plus a parity disk plus a hot swap do we need
>to
>> >worry
>> >> about losing a redo log? Our sys admins are telling us we don't
>
>> >and I
>> >> tend to agree with them but we want to get other opinions on
>the
>> >> subject.
>> >>
>> >> How are shops handling this who are using raid5?
>> >>
>> >> Thanks.
>> >> Joe
>> >> --
>> >> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> >> --
>> >> Author: Joe Armstrong-Champ
>> >> INET: Joseph.Armstrong-Champ_at_tufts.edu
>> >>
>> >> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> >> San Diego, California -- Public Internet access / Mailing
>
>> >Lists
>> >>
>> --------------------------------------------------------------------
>> >> To REMOVE yourself from this mailing list, send an E-Mail message
>> >> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru')
>and
>> >in
>> >> the message BODY, include a line containing: UNSUB ORACLE-L
>> >> (or the name of mailing list you want to be removed from).
>You
>> >may
>> >> also send the HELP command for other information (like
>> subscribing).
>> >> --
>> >> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> >> --
>> >> Author: Fink, Dan
>> >> INET: Dan.Fink_at_mdx.com
>> >>
>> >> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> >> San Diego, California -- Public Internet access / Mailing
>
>> >Lists
>> >>
>> --------------------------------------------------------------------
>> >> To REMOVE yourself from this mailing list, send an E-Mail message
>> >> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru')
>and
>> >in
>> >> the message BODY, include a line containing: UNSUB ORACLE-L
>> >> (or the name of mailing list you want to be removed from).
>You
>> >may
>> >> also send the HELP command for other information (like
>> subscribing).
>> >--
>> >Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> >--
>> >Author: Joe Armstrong-Champ
>> > INET: joseph.armstrong-champ_at_tufts.edu
>> >
>> >Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> >San Diego, California -- Public Internet access / Mailing
>
>> >Lists
>> >--------------------------------------------------------------------
>> >To REMOVE yourself from this mailing list, send an E-Mail message
>> >to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and
>
>> >in
>> >the message BODY, include a line containing: UNSUB ORACLE-L
>> >(or the name of mailing list you want to be removed from). You
>may
>> >also send the HELP command for other information (like subscribing).
>> >--
>> >Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> >--
>> >Author: Fink, Dan
>> > INET: Dan.Fink_at_mdx.com
>> >
>> >Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> >San Diego, California -- Public Internet access / Mailing
>
>> >Lists
>> >--------------------------------------------------------------------
>> >To REMOVE yourself from this mailing list, send an E-Mail message
>> >to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and
>
>> >in
>> >the message BODY, include a line containing: UNSUB ORACLE-L
>> >(or the name of mailing list you want to be removed from). You
>may
>> >also send the HELP command for other information (like subscribing).
>> >
>> >
>>
>> --
>> Please see the official ORACLE-L FAQ: http://www.orafaq.com
>> --
>> Author: Alan Davey
>> INET: adavey_at_competitrack.com
>>
>> Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>> San Diego, California -- Public Internet access / Mailing
>Lists
>> --------------------------------------------------------------------
>> To REMOVE yourself from this mailing list, send an E-Mail message
>> to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and
>in
>> the message BODY, include a line containing: UNSUB ORACLE-L
>> (or the name of mailing list you want to be removed from). You
>may
>> also send the HELP command for other information (like subscribing).
>>
>--
>Please see the official ORACLE-L FAQ: http://www.orafaq.com
>--
>Author: Gogala, Mladen
> INET: MGogala_at_oxhp.com
>
>Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
>San Diego, California -- Public Internet access / Mailing
>Lists
>--------------------------------------------------------------------
>To REMOVE yourself from this mailing list, send an E-Mail message
>to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and
>in
>the message BODY, include a line containing: UNSUB ORACLE-L
>(or the name of mailing list you want to be removed from). You may
>also send the HELP command for other information (like subscribing).
>
>
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Alan Davey
INET: adavey_at_competitrack.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
Received on Thu Aug 08 2002 - 09:18:21 CDT
