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Home -> Community -> Mailing Lists -> Oracle-L -> RE: oracle clustering
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I do not understand how it will go away entirely. Alleviated maybe. My understanding that pinging will continue to occur but not thru disk but moving buffers thru fast interconnect.
Alex Hillman
-----Original Message-----
From: Adams, Matthew (GEA, 088130) [mailto:MATT.ADAMS_at_appl.ge.com]
Sent: Wednesday, November 29, 2000 2:41 PM
To: Multiple recipients of list ORACLE-L
Subject: RE: oracle clustering
What Chuck says is true to a point. However, they failover and recovery times for and OPS cluster and a non-ops cluster can be significantly different.
We use HP ServiceGuard clustering and OPS.
A failover using OPS takes
about 30 seconds at most (for us) and requires
NO manual intervention to accomplish the reocovery.
A failover using ServiceGuard Clustering
takes about 10-15 minutes and may
(under rare circumstances) require
manual intervention to accomplish the recovery.
Also, pinging became less of a problem with the dynamic PCM locking (8.0) and even less of an issue with Cache Fusion (8.1.6). Supposedly, it goes away entire with 9i.
-----Original Message-----
<mailto:chuck_hamilton_at_yahoo.com> ]
Sent: Wednesday, November 29, 2000 12:21 PM
To: Multiple recipients of list ORACLE-L
Then the answer is no. Oracle clustering is not the same as OPS. OPS is not necessary for high availability either, though it does make the database more highly available then single instance oracle on a cluster.
I once thought OPS gave you 100% availability because multiple instances were running on separate machines sharing the same physical database. If one machine or instance failed, the others continued to run uninterruppted. The 2nd (and 3rd, 4th,... Nth) instances do continue to run but there is an interruption in service when any one instance fails. There is a period of time known as a "brown out" where *no* work can be done on the database. During that time the DLM (distibuted lock manager) which controls concurrency between the instances must reconfigure itself to run accross only the surviving instances. Then an instance recovery must be performed on behalf of the failed instance. Only after this is done can work continue on the database. When the failed instance comes back online the DLM must be reconfigured again to include the new instance. OPS is also only available on a few platforms (IBM, HP, SUN, and Compaq).
Single instance oracle clustering OTOH is implemented entirely through the platforms cluster management software. The instance runs on only one node at a time. Should the instance or node fail, the cluster manager software shuts the instance down, unmounts the disks, remounts them on another node, and starts the oracle instance on that node.
Single instance oracle running on a cluster manager is still highly available and much easier to administer than OPS. For example, your application must be redesigned around OPS. In order to reduce pinging of blocks between nodes (which requires physical disk i/o much of the time), you need to segregate your apps and users amongst the nodes in such a way as to eliminate reduce the chance that multiple nodes will need access to the same database blocks. This is not always an easy task. If you don't do this you could see your performance go down the toilet even though you're adding more nodes and cpus. Trying to identify contention between instances is not an easy task either.
Having been to the OPS class and actually working with it, I'm not convinced it buys me enough availability to warrant it's use instead of single instance oracle on a cluster. Either way when an instance fails you have to perform instance recovery. The only thing OPS saves you is the time it takes to move the disk mounts and start an instance. And the cost for that small amount of time is an application redesign. Only data warehouses typically can be dropped righ on to OPS with little or no changes because of there read-only nature.
HTH Chuck Hamilton
Herman <Sherman_at_bcsis.com> wrote:
what i mean is the clustering to obtain high availability.
and i heard this can be achieved thru OPS,
anyone can comment about this ?
thanks &
regards
Herman
To: Multiple recipients of list ORACLE-L <mailto:ORACLE-L_at_fatcity.com>
Sent: Tuesday, November 28, 2000 1:25 AM
I'm not sure what you're referring to by "oracle clustering". Is this a product you've heard of? I'm not familiar with it. Inside the database, clustering is the term for nesting multiple tables within the same segment for faster joins. Could that be what you're thinking about? Outside the database, clustering is a means of attaining high availability and is required for OPS. Single instance Oracle can also run on a cluster apart from OPS but is not quite as highly available.
Herman <Sherman_at_bcsis.com> wrote:
hello all,
can somebody plz help me to explain about oracle clustering ? is oracle clustering equal to Oracle Parallel Server ? is it considered as software clustering ?
wha'ts the different, advantage and disadvantage bettween software clustering and hardware clustering anyway ? can we combine those two when we implement OPS ?
thanks
and regards
Herman
-- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Herman INET: Sherman_at_bcsis.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). _____ Do You Yahoo!? Yahoo! Shopping <http://shopping.yahoo.com/> - Thousands of Stores. Millions of Products. _____ Do You Yahoo!? Yahoo! <http://shopping.yahoo.com/> Shopping - Thousands of Stores. Millions of Products. -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: Adams, Matthew (GEA, 088130) INET: MATT.ADAMS_at_APPL.GE.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). ------_=_NextPart_001_01C05A4D.231084B0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printableReceived on Wed Nov 29 2000 - 15:41:31 CST
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<P><FONT SIZE=3D2>I do not understand how it will go away entirely. =
Alleviated maybe. My understanding that pinging will continue to occur = but not thru disk but moving buffers thru fast interconnect. =
</FONT></P>
<P><FONT SIZE=3D2>Alex Hillman</FONT>
</P>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2>From: Adams, Matthew (GEA, 088130) [<A =
HREF=3D"mailto:MATT.ADAMS_at_appl.ge.com">mailto:MATT.ADAMS_at_appl.ge.com</A>= ]</FONT>
<BR><FONT SIZE=3D2>Sent: Wednesday, November 29, 2000 2:41 PM</FONT>
<BR><FONT SIZE=3D2>To: Multiple recipients of list ORACLE-L</FONT>
<BR><FONT SIZE=3D2>Subject: RE: oracle clustering</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>What Chuck says is true to a point. However, =
they failover</FONT>
<BR><FONT SIZE=3D2>and recovery times for and OPS cluster and </FONT>
<BR><FONT SIZE=3D2>a non-ops cluster can be significantly =
different.</FONT>
<BR><FONT SIZE=3D2> </FONT>
<BR><FONT SIZE=3D2>We use HP ServiceGuard clustering and OPS.</FONT>
<BR><FONT SIZE=3D2> </FONT>
<BR><FONT SIZE=3D2>A failover using OPS takes</FONT>
<BR><FONT SIZE=3D2>about 30 seconds at most (for us) and =
requires</FONT>
<BR><FONT SIZE=3D2>NO manual intervention to accomplish the =
reocovery.</FONT>
<BR><FONT SIZE=3D2> </FONT>
<BR><FONT SIZE=3D2>A failover using ServiceGuard Clustering</FONT>
<BR><FONT SIZE=3D2>takes about 10-15 minutes and may </FONT>
<BR><FONT SIZE=3D2>(under rare circumstances) require</FONT>
<BR><FONT SIZE=3D2>manual intervention to accomplish the =
recovery.</FONT>
<BR><FONT SIZE=3D2> </FONT>
<BR><FONT SIZE=3D2>Also, pinging became less of a problem with the =
</FONT>
<BR><FONT SIZE=3D2>dynamic PCM locking (8.0) and even less of an</FONT>
<BR><FONT SIZE=3D2>issue with Cache Fusion (8.1.6). Supposedly, =
</FONT>
<BR><FONT SIZE=3D2>it goes away entire with 9i.</FONT>
<BR><FONT SIZE=3D2> </FONT>
<BR><FONT SIZE=3D2> </FONT>
</P>
<P><FONT SIZE=3D2>---- </FONT>
<BR><FONT SIZE=3D2>R. Matt Adams - GE Appliances - =
matt.adams_at_appl.ge.com </FONT>
<BR><FONT SIZE=3D2> It will make sense when you stop thinking =
logically </FONT>
<BR><FONT SIZE=3D2> and start thinking =
Oracle-ly - Jim Droppa </FONT>
</P>
<P><FONT SIZE=3D2> </FONT>
</P>
<P><FONT SIZE=3D2>-----Original Message-----</FONT>
<BR><FONT SIZE=3D2><<A =
HREF=3D"mailto:chuck_hamilton_at_yahoo.com">mailto:chuck_hamilton_at_yahoo.com=
</A>> ]</FONT>
<BR><FONT SIZE=3D2>Sent: Wednesday, November 29, 2000 12:21 PM</FONT>
<BR><FONT SIZE=3D2>To: Multiple recipients of list ORACLE-L</FONT>
</P>
<BR>
<BR>
<P><FONT SIZE=3D2>Then the answer is no. Oracle clustering is not the =
same as OPS. OPS is not</FONT>
<BR><FONT SIZE=3D2>necessary for high availability either, though it =
does make the database</FONT>
<BR><FONT SIZE=3D2>more highly available then single instance oracle on =
a cluster. </FONT>
</P>
<P><FONT SIZE=3D2>I once thought OPS gave you 100% availability because =
multiple instances</FONT>
<BR><FONT SIZE=3D2>were running on separate machines sharing the same =
physical database. If one</FONT>
<BR><FONT SIZE=3D2>machine or instance failed, the others continued to =
run uninterruppted. The</FONT>
<BR><FONT SIZE=3D2>2nd (and 3rd, 4th,... Nth) instances do continue to =
run but there is an</FONT>
<BR><FONT SIZE=3D2>interruption in service when any one instance fails. =
There is a period of</FONT>
<BR><FONT SIZE=3D2>time known as a "brown out" where *no* =
work can be done on the database.</FONT>
<BR><FONT SIZE=3D2>During that time the DLM (distibuted lock manager) =
which controls</FONT>
<BR><FONT SIZE=3D2>concurrency between the instances must reconfigure =
itself to run accross</FONT>
<BR><FONT SIZE=3D2>only the surviving instances. Then an instance =
recovery must be performed on</FONT>
<BR><FONT SIZE=3D2>behalf of the failed instance. Only after this is =
done can work continue on</FONT>
<BR><FONT SIZE=3D2>the database. When the failed instance comes back =
online the DLM must be</FONT>
<BR><FONT SIZE=3D2>reconfigured again to include the new instance. OPS =
is also only available</FONT>
<BR><FONT SIZE=3D2>on a few platforms (IBM, HP, SUN, and =
Compaq).</FONT>
</P>
<P><FONT SIZE=3D2>Single instance oracle clustering OTOH is implemented =
entirely through the</FONT>
<BR><FONT SIZE=3D2>platforms cluster management software. The instance =
runs on only one node at</FONT>
<BR><FONT SIZE=3D2>a time. Should the instance or node fail, the =
cluster manager software shuts</FONT>
<BR><FONT SIZE=3D2>the instance down, unmounts the disks, remounts them =
on another node, and</FONT>
<BR><FONT SIZE=3D2>starts the oracle instance on that node.</FONT>
</P>
<P><FONT SIZE=3D2>Single instance oracle running on a cluster manager =
is still highly</FONT>
<BR><FONT SIZE=3D2>available and much easier to administer than OPS. =
For example, your</FONT>
<BR><FONT SIZE=3D2>application must be redesigned around OPS. In order =
to reduce pinging of</FONT>
<BR><FONT SIZE=3D2>blocks between nodes (which requires physical disk =
i/o much of the time),</FONT>
<BR><FONT SIZE=3D2>you need to segregate your apps and users amongst =
the nodes in such a way as</FONT>
<BR><FONT SIZE=3D2>to eliminate reduce the chance that multiple nodes =
will need access to the</FONT>
<BR><FONT SIZE=3D2>same database blocks. This is not always an easy =
task. If you don't do this</FONT>
<BR><FONT SIZE=3D2>you could see your performance go down the toilet =
even though you're adding</FONT>
<BR><FONT SIZE=3D2>more nodes and cpus. Trying to identify contention =
between instances is not</FONT>
<BR><FONT SIZE=3D2>an easy task either. </FONT>
</P>
<P><FONT SIZE=3D2>Having been to the OPS class and actually working =
with it, I'm not convinced</FONT>
<BR><FONT SIZE=3D2>it buys me enough availability to warrant it's use =
instead of single</FONT>
<BR><FONT SIZE=3D2>instance oracle on a cluster. Either way when an =
instance fails you have to</FONT>
<BR><FONT SIZE=3D2>perform instance recovery. The only thing OPS saves =
you is the time it takes</FONT>
<BR><FONT SIZE=3D2>to move the disk mounts and start an instance. And =
the cost for that small</FONT>
<BR><FONT SIZE=3D2>amount of time is an application redesign. Only data =
warehouses typically</FONT>
<BR><FONT SIZE=3D2>can be dropped righ on to OPS with little or no =
changes because of there</FONT>
<BR><FONT SIZE=3D2>read-only nature.</FONT>
</P>
<P><FONT SIZE=3D2>HTH</FONT>
</P>
<P><FONT SIZE=3D2>Chuck Hamilton</FONT>
</P>
<BR>
<P><FONT SIZE=3D2> Herman <Sherman_at_bcsis.com> wrote: =
</FONT>
</P>
<BR>
<BR>
<BR>
<BR>
<BR>
<P><FONT SIZE=3D2>what i mean is the clustering to obtain high =
availability.</FONT>
</P>
<P><FONT SIZE=3D2>and i heard this can be achieved thru OPS,</FONT>
</P>
<P><FONT SIZE=3D2>anyone can comment about this ?</FONT>
</P>
<P><FONT SIZE=3D2> </FONT>
</P>
<P><FONT SIZE=3D2>thanks &</FONT>
</P>
<P><FONT SIZE=3D2>regards</FONT>
</P>
<P><FONT SIZE=3D2> </FONT>
</P>
<P><FONT SIZE=3D2>Herman</FONT>
</P>
<P><FONT SIZE=3D2> </FONT>
</P>
<BR>
<BR>
<P><FONT SIZE=3D2>----- Original Message ----- </FONT>
</P>
<BR>
<P><FONT SIZE=3D2>To: Multiple recipients of list ORACLE-L <<A =
HREF=3D"mailto:ORACLE-L_at_fatcity.com">mailto:ORACLE-L_at_fatcity.com</A>>= </FONT>
</P>
<P><FONT SIZE=3D2>Sent: Tuesday, November 28, 2000 1:25 AM</FONT>
</P>
<BR>
<BR>
<BR>
<BR>
<P><FONT SIZE=3D2>I'm not sure what you're referring to by "oracle =
clustering". Is this a</FONT>
<BR><FONT SIZE=3D2>product you've heard of? I'm not familiar with it. =
Inside the database,</FONT>
<BR><FONT SIZE=3D2>clustering is the term for nesting multiple tables =
within the same segment</FONT>
<BR><FONT SIZE=3D2>for faster joins. Could that be what you're thinking =
about? Outside the</FONT>
<BR><FONT SIZE=3D2>database, clustering is a means of attaining high =
availability and is</FONT>
<BR><FONT SIZE=3D2>required for OPS. Single instance Oracle can also =
run on a cluster apart</FONT>
<BR><FONT SIZE=3D2>from OPS but is not quite as highly =
available.</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>Herman <Sherman_at_bcsis.com> wrote: </FONT>
</P>
<BR>
<BR>
<P><FONT SIZE=3D2>hello all,</FONT>
</P>
<P><FONT SIZE=3D2>can somebody plz help me to explain about oracle =
clustering ?</FONT>
<BR><FONT SIZE=3D2>is oracle clustering equal to Oracle Parallel Server =
?</FONT>
<BR><FONT SIZE=3D2>is it considered as software clustering ?</FONT>
</P>
<P><FONT SIZE=3D2>wha'ts the different, advantage and disadvantage =
bettween software</FONT>
<BR><FONT SIZE=3D2>clustering and hardware clustering anyway ?</FONT>
<BR><FONT SIZE=3D2>can we combine those two when we implement OPS =
?</FONT>
</P>
<BR>
<P><FONT SIZE=3D2>thanks</FONT>
<BR><FONT SIZE=3D2>and regards</FONT>
<BR><FONT SIZE=3D2>Herman</FONT>
</P>
<P><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Please see the official ORACLE-L FAQ: <A =
HREF=3D"http://www.orafaq.com" = TARGET=3D"_blank">http://www.orafaq.com</A></FONT>
<BR><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Author: Herman</FONT>
<BR><FONT SIZE=3D2>INET: Sherman_at_bcsis.com</FONT>
</P>
<P><FONT SIZE=3D2>Fat City Network Services -- (858) 538-5051 FAX: =
(858) 538-5051</FONT>
<BR><FONT SIZE=3D2>San Diego, California -- Public Internet access / =
Mailing Lists</FONT>
<BR><FONT =
SIZE=3D2>---------------------------------------------------------------= -----</FONT>
<BR><FONT SIZE=3D2>To REMOVE yourself from this mailing list, send an =
E-Mail message</FONT>
<BR><FONT SIZE=3D2>to: ListGuru_at_fatcity.com (note EXACT spelling of =
'ListGuru') and in</FONT>
<BR><FONT SIZE=3D2>the message BODY, include! ! ! ! ! ! a line =
containing: UNSUB ORACLE-L</FONT>
<BR><FONT SIZE=3D2>(or the name of mailing list you want to be removed =
from). You may</FONT>
<BR><FONT SIZE=3D2>also send the HELP command for other information =
(like subscribing).</FONT>
</P>
<BR>
<BR>
<BR>
<BR>
<BR>
<P><FONT SIZE=3D2> _____ </FONT>
</P>
<BR>
<P><FONT SIZE=3D2>Do You Yahoo!?</FONT>
<BR><FONT SIZE=3D2>Yahoo! Shopping <<A =
HREF=3D"http://shopping.yahoo.com/" = TARGET=3D"_blank">http://shopping.yahoo.com/</A>> - Thousands = of Stores.</FONT>
<BR><FONT SIZE=3D2>Millions of Products.</FONT>
</P>
<BR>
<BR>
<BR>
<P><FONT SIZE=3D2> _____ </FONT>
</P>
<P><FONT SIZE=3D2>Do You Yahoo!?</FONT>
<BR><FONT SIZE=3D2>Yahoo! <<A =
HREF=3D"http://shopping.yahoo.com/" = TARGET=3D"_blank">http://shopping.yahoo.com/</A>> Shopping - = Thousands of Stores.</FONT>
<BR><FONT SIZE=3D2>Millions of Products.</FONT>
</P>
<P><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Please see the official ORACLE-L FAQ: <A =
HREF=3D"http://www.orafaq.com" = TARGET=3D"_blank">http://www.orafaq.com</A></FONT>
<BR><FONT SIZE=3D2>-- </FONT>
<BR><FONT SIZE=3D2>Author: Adams, Matthew (GEA, 088130)</FONT>
<BR><FONT SIZE=3D2> INET: MATT.ADAMS_at_APPL.GE.COM</FONT>
</P>
<P><FONT SIZE=3D2>Fat City Network Services -- (858) =
538-5051 FAX: (858) 538-5051</FONT>
<BR><FONT SIZE=3D2>San Diego, =
California -- Public Internet = access / Mailing Lists</FONT>
<BR><FONT =
SIZE=3D2>---------------------------------------------------------------=
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