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yipeee!


Just recieved a 'thought experiment' assignment from my boss.
Does it make sense, and how would it be accomplised, to move
the databases from the mainframe (small VSE 390?) to AIX?
I mentioned that we should then look at possible programs from
IBM to convert the mainframe database (VSAM?) files into DB2/AIX,
or Oracle databases. And that I thought Oracle had some facility
such that we could cluster and load-balance two+ nodes running
something like Parallel Oracle so that should a node need booting
or modifying off-line the application is still running (at
reduced capacity) for the users.

Thoughts?

Mike
Nov 12 '05
95 5385
"Mark A" <ma@switchboard .net> wrote in message
news:Oh******** ********@news.u swest.net...
The odds of a medium scale application development project ever being
completed with code in production is less than 50%.
they decrease to 0% if the developer is IBM/GSA...
Of the remaining 50%
that make it into production, the vast majority of those projects will be
over way budget and/or seriously late to completion.


You forgot: dumbed-down so that SOMETHING can be delivered to the client...

--
Cheers
Nuno Souto
wi*******@yahoo .com.au.nospam
Nov 12 '05 #41
Daniel Morgan <da******@x.was hington.edu> wrote in message news:<107594886 8.103447@yasure >...
As has been frequently stated in the DB2 usenet group and elsewhere ...
the TPC benchmarks favor shared-nothing. Pull the plug on one of those
shared nothing nodes (hardware failures do happen in the real world) and
see what happens to performance.

My point being that if I made one change to the benchmark ... say added
the following ... "one hour into the test pull the plug on one node and
complete the job" ... shared nothing and federated databases wouldn't
even be able to compete.


Kind of neat how as soon as product a has a new feature its apologists
declare it the essential and distinguishing feature in the
marketplace..

Now, if it works as smoothly as you describe - that's great, and I'll
look forward to using it. On the other hand, in my experience with
MPP databases (primarily Informix on AIX using SP2), I could go a year
without having to reboot any nodes. And when I did, it was often due
to a configuration change to the frame - so I had to take all of them
down anyway.

So, nice feature, but hardly essential for most applications.
Nov 12 '05 #42
My DB2 "offer" would be DB2 without DPF on two AIX boxes (OP wants AIX
it seems). The seoncd box licenced as idle standby only (1 CPU).
With clusterware to handle the failover.
This is under the assumption that a rewrite of the app to a relational
DBMS is intended.
There is not enough information to home in on which edition or box-size
to home in to.

It seems Mark A. believes CICS would be less invasive. I'm not familiar
with either VSE or CICS so I keep my mouth shut.

Let's presume 100% scalability for RAC (if you want to use it) for the
sake of math (and to not start another flame war) and similar resource
requirements (AIX, RAM/box, comparable disk overall).

Your turn
Serge
--
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab
Nov 12 '05 #43
"Serge Rielau" <sr*****@ca.e ye-be-em.com> wrote in message
news:bv******** **@hanover.toro lab.ibm.com...
My DB2 "offer" would be DB2 without DPF on two AIX boxes (OP wants AIX
it seems). The seoncd box licenced as idle standby only (1 CPU).
With clusterware to handle the failover.
This is under the assumption that a rewrite of the app to a relational
DBMS is intended.
There is not enough information to home in on which edition or box-size
to home in to.

It seems Mark A. believes CICS would be less invasive. I'm not familiar
with either VSE or CICS so I keep my mouth shut.

Let's presume 100% scalability for RAC (if you want to use it) for the
sake of math (and to not start another flame war) and similar resource
requirements (AIX, RAM/box, comparable disk overall).

Your turn
Serge
--
Serge Rielau
DB2 SQL Compiler Development
IBM Toronto Lab


I think that what they want to do is change the COBOL application data
access from VSAM to DB2, running under CICS transaction monitor on RS6000.
This could be done without a complete redesign of the application, although
database access in each program would have to be changed by hand from VSAM
to DB2 and thoroughly tested. VSAM KSDS is an inverted list database (not
hierarchical like IMS) so there could be a one-to-one mapping of existing
VSAM datasets to DB2 tables.

But again, I think their main motivation is to save money, and the
conversion certainly would not be cheap, although much less expensive than a
complete re-write.

The hardware redundancy issues could be worked out in a number of ways, as
already mentioned.
Nov 12 '05 #44
"Serge Rielau" <sr*****@ca.e ye-be-em.com> wrote in message
news:bv******** **@hanover.toro lab.ibm.com...
My DB2 "offer" would be DB2 without DPF on two AIX boxes (OP wants AIX
it seems). The seoncd box licenced as idle standby only (1 CPU).
With clusterware to handle the failover.
This is under the assumption that a rewrite of the app to a relational
DBMS is intended.
There is not enough information to home in on which edition or box-size
to home in to.

It seems Mark A. believes CICS would be less invasive. I'm not familiar
with either VSE or CICS so I keep my mouth shut.
ditto.


Let's presume 100% scalability for RAC (if you want to use it) for the
sake of math (and to not start another flame war) and similar resource
requirements (AIX, RAM/box, comparable disk overall).

Your turn
Serge


:(

I think I would go with one of

two AIX boxes one running DB with Oracle DataGuard to handle standby to the
second pretty much as per your solution.
n box implementation of 9i RAC with transparent application failover.
On the other hand the more we learn about the app the more business critical
it seems and so the more conservative (read why move it at all?) I become.
--
Niall Litchfield
Oracle DBA
Audit Commission UK
Nov 12 '05 #45
Daniel Morgan wrote:
Niall Litchfield wrote:
"Rob Cowell" <rj*****@hotmai l.com> wrote in message
news:40******** *******@hotmail .com...
And that I thought Oracle had some facility
such that we could cluster and load-balance two+ nodes running
something like Parallel Oracle so that should a node need booting
or modifying off-line the application is still running (at
reduced capacity) for the users.

Oracle Real Application Clusters


http://tahiti.oracle.com/pls/db92/db...ation+clusters

Just to add to that, if you are writing the app from scratch RAC also
supports a technology (transparent application failover) where users
connected to a node that fails will failover to a running node without
dataloss and without being disconnected from the application. I am
unsure if
IBM have a similar technology


Only on mainframes. With shared nothing if you lose a node ... the
storage associated with that node is lost too.


Yep. Also, I really don't want to sound like I'm picking only on Oracle,
because I complain about other DBMSes too. Oracle's TAF fooled a number
of customers into believing it really was Transparent Application Failover,
but it seems to be so only for certain mostly-idle clients. The reason I
say this is because while there is no data loss during a failover, nor
even any transactional context (locks), what is lost is any *computational*
context that the client may be relying on if it was actually doing
something when the failover occurred. For instance, most cursor context
is lost. Java clients that may have created and are re-using Prepared
Statements will find that all those prepared statements are now defunct,
and must be recreated before the client can even retry what they were doing.
This generally means returning to the line of code right after obtaining the
original connection. Having the connection automatically failover to an
appropriate backup DBMS is certainly valuable, but calling it "TAF" was
'aiming high' in the marketing department, IMHO.
Joe

Nov 12 '05 #46
Joe Weinstein wrote:
Yep. Also, I really don't want to sound like I'm picking only on Oracle,
because I complain about other DBMSes too. Oracle's TAF fooled a number
of customers into believing it really was Transparent Application Failover,
but it seems to be so only for certain mostly-idle clients. The reason I
say this is because while there is no data loss during a failover, nor
even any transactional context (locks), what is lost is any *computational*
context that the client may be relying on if it was actually doing
something when the failover occurred. For instance, most cursor context
is lost. Java clients that may have created and are re-using Prepared
Statements will find that all those prepared statements are now defunct,
and must be recreated before the client can even retry what they were
doing.
This generally means returning to the line of code right after obtaining
the
original connection. Having the connection automatically failover to an
appropriate backup DBMS is certainly valuable, but calling it "TAF" was
'aiming high' in the marketing department, IMHO.
Joe


From the client's standpoint it is completely transparent which is the
origin of the name.

Perhaps you need to come take the class I teach on RAC.

--
Daniel Morgan
http://www.outreach.washington.edu/e...ad/oad_crs.asp
http://www.outreach.washington.edu/e...oa/aoa_crs.asp
da******@x.wash ington.edu
(replace 'x' with a 'u' to reply)

Nov 12 '05 #47
Daniel Morgan wrote:
Joe Weinstein wrote:
Yep. Also, I really don't want to sound like I'm picking only on Oracle,
because I complain about other DBMSes too. Oracle's TAF fooled a number
of customers into believing it really was Transparent Application
Failover,
but it seems to be so only for certain mostly-idle clients. The reason I
say this is because while there is no data loss during a failover, nor
even any transactional context (locks), what is lost is any
*computational*
context that the client may be relying on if it was actually doing
something when the failover occurred. For instance, most cursor context
is lost. Java clients that may have created and are re-using Prepared
Statements will find that all those prepared statements are now defunct,
and must be recreated before the client can even retry what they were
doing.
This generally means returning to the line of code right after
obtaining the
original connection. Having the connection automatically failover to an
appropriate backup DBMS is certainly valuable, but calling it "TAF" was
'aiming high' in the marketing department, IMHO.
Joe

From the client's standpoint it is completely transparent which is the
origin of the name.

Perhaps you need to come take the class I teach on RAC.


I guess it's a question how you define 'completely transparent'. Of course,
the client has to do nothing but sit there and wait until the connection
is failed over. However, one might argue that just having lost my running
transaction (insert, update, delete) and all my package states is all that
transparent.
But I'm still impressed how the new node is able to pick up a running query
and continue at the same point where the failover occured - since a resultset
per definition has no order (except when specified) I'm still wondering how
the node I failed over to is able to bypass that restriction. It was a question
the teacher of my RAC course couldn't quite answer, but then maybe he just
knew so much more of the internal mechanics that he needn't to wonder ;-)

Cheer up, that cast on your leg won't last forever ;-)

Holger

Nov 12 '05 #48
Holger Baer wrote:

I'm still wondering how
the node I failed over to is able to bypass that restriction. It was a
question
the teacher of my RAC course couldn't quite answer, but then maybe he just
knew so much more of the internal mechanics that he needn't to wonder ;-)

Cheer up, that cast on your leg won't last forever ;-)

Holger


Thanks ... just 11 more days.

The way it is done is through something a combination of shared
everything ... meaning that each node sees the same database files, the
same data, and can also see the same redo logs and rollback segements.
Thus if one node fails ... any other node can see everything on disk
that was in use by any other node. Add to that cache fusion ... the
ability to pass memory caches between nodes and the only thing one node
needs to know about another node to fail-over is what failed and where.
We routinely see restarts in the <60 second range.

--
Daniel Morgan
http://www.outreach.washington.edu/e...ad/oad_crs.asp
http://www.outreach.washington.edu/e...oa/aoa_crs.asp
da******@x.wash ington.edu
(replace 'x' with a 'u' to reply)

Nov 12 '05 #49
bu*********@yah oo.com (Buck Nuggets) wrote in message news:<66******* *************** ****@posting.go ogle.com>...
Daniel Morgan <da******@x.was hington.edu> wrote:
My point being that if I made one change to the benchmark ... say added
the following ... "one hour into the test pull the plug on one node and
complete the job" ... shared nothing and federated databases wouldn't
even be able to compete.


Kind of neat how as soon as product a has a new feature its apologists
declare it the essential and distinguishing feature in the
marketplace..

Now, if it works as smoothly as you describe - that's great, and I'll
look forward to using it. On the other hand, in my experience with
MPP databases (primarily Informix on AIX using SP2), I could go a year
without having to reboot any nodes.


Daniel seems to think otherwise. He clearly feels that Oracle's
allegedly faster recover from node failures outweighs its
less-than-half-speed RAC performance under BAU circumstances (i.e.
nodes working). I can't understand why Oracle nodes crash so much, but
it's not a product I know well. Hopefully someone else will explain.
DG
Nov 12 '05 #50

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