64-bit instance on Aix 32 bit kernel / 64 bit hardware

[Jean-Marc Blaise]

Hi,

Is it worth to use 64-bit DB2 instances on a 32-bit kernel, in terms of:
- performance
- configuration (go beyond the 256 Mb segment for private mem, 1.75 Gb for
Bufferpools)
- other ?

I've seen NIS is not supported, downlevel (64 to 32 bit ?) is not supported
....

The "Should I be using DB2 64-bit?" tech note seems confusing:
http://www-1.ibm.com/support/docview...=utf-8&lang=en

It states some restrictions
- You can install 64-bit DB2 UDB Version 8 on 32-bit operating systems only
on AIX, HP-UX and Solaris Operating Environments. ==>You will not be able to
create or run 64-bit instances. You can only create and run 32-bit
instances. <== Really ?

The db2setup (8.2 / Aix) asked for 32-bit or 64-bit instance creation. It
seems db2iupdt -w 64 works fine, and the instance is functionning, but is it
worth ?

Thanks for your help,

Jean-Marc

[Larry E]

Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you cannot
create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS, even
if you are able to get it to work and it even if it IS supported.

Larry Edelstein

Jean-Marc Blaise wrote:

Hi,

Is it worth to use 64-bit DB2 instances on a 32-bit kernel, in terms of:
- performance
- configuration (go beyond the 256 Mb segment for private mem, 1.75 Gb for
Bufferpools)
- other ?

I've seen NIS is not supported, downlevel (64 to 32 bit ?) is not supported
....

The "Should I be using DB2 64-bit?" tech note seems confusing:
http://www-1.ibm.com/support/docview...=utf-8&lang=en

It states some restrictions
- You can install 64-bit DB2 UDB Version 8 on 32-bit operating systems only
on AIX, HP-UX and Solaris Operating Environments. ==>You will not be able to
create or run 64-bit instances. You can only create and run 32-bit
instances. <== Really ?

The db2setup (8.2 / Aix) asked for 32-bit or 64-bit instance creation. It
seems db2iupdt -w 64 works fine, and the instance is functionning, but is it
worth ?

Thanks for your help,

Jean-Marc

[Darin McBride]

Larry E wrote:

Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you cannot
create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS, even
if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

[Jean-Marc Blaise]

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:

Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you cannot
create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS, even
if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the db2setup
propose to create a 64-bit instance ? I think a 'bootinfo -K' can be done to
check if we are 32 or 64 bit kernel, and in case of 32-bit, it should NOT
propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,
but there must be a reason somewhere as AIX does support it.

Best regards,

Jean-Marc

[Jean-Marc Blaise]

"Jean-Marc Blaise" <no****@nowhere.com> a écrit dans le message de
news:42**********************@news.wanadoo.fr...

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:

Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you cannot create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS, even if you are able to get it to work and it even if it IS supported.
My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the

db2setup propose to create a 64-bit instance ? I think a 'bootinfo -K' can be done to check if we are 32 or 64 bit kernel, and in case of 32-bit, it should NOT
propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,
but there must be a reason somewhere as AIX does support it.

Best regards,

Jean-Marc

.... By the way, it seems Oracle installs in 64-bit only on such machines ...
so why would DB2 avoid this support ?

[Larry]

How do you know that Oracle supports it?

Larry Edelstein

Jean-Marc Blaise wrote:

"Jean-Marc Blaise" <no****@nowhere.com> a écrit dans le message de
news:42**********************@news.wanadoo.fr...

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:
Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you
cannot
create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS,
even
if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the

db2setup

propose to create a 64-bit instance ? I think a 'bootinfo -K' can be done

to

check if we are 32 or 64 bit kernel, and in case of 32-bit, it should NOT
propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,
but there must be a reason somewhere as AIX does support it.

Best regards,

Jean-Marc

.... By the way, it seems Oracle installs in 64-bit only on such machines ...
so why would DB2 avoid this support ?

[Darin McBride]

Jean-Marc Blaise wrote:

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:

> Jean-Marc,
>
> I believe what the technote is trying to say is you can install the
> 64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
> once you install the DB2 binaries, you must create DB2 instances in
> order to operate a DB2 database. I believe it is saying that you cannot
> create 64-bit instances under a 32-bit OS. If you didn't receive an
> error in attempting to do so, I guess you are in uncharted territory,
> and risk not being able to get support from IBM. I'm not sure that
> there's any advantage to using a 64-bit instance under a 32-bit OS,
> even if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the
db2setup propose to create a 64-bit instance ? I think a 'bootinfo -K' can
be done to check if we are 32 or 64 bit kernel, and in case of 32-bit, it
should NOT propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,
but there must be a reason somewhere as AIX does support it.

I doubt it's "simulation" - I expect that since the processor can
handle 64-bit, the 32-bit kernel was just modified to allow 64-bit
programs to be controlled by it.

And why would db2setup allow 64-bit? Simple - users run all sorts of
unsupported scenarios. Many of them work. DB2 doesn't exactly want to
say it's smarter than the user when it can help it - if you really need
to run 64-bit on a 32-bit kernel, db2setup should not prevent it. This
is different from DB2's autonomic computing in that you can turn that
off. Since db2setup is run before you can configure DB2, it's hard to
turn off autonomic computing functionality there. It's a delicate line
which I'm sure db2setup jumps from side to side depending on the issue,
but we're definitely open to feedback about which side of the line
db2setup should be on for each issue.

Here's a scenario that would be, in my mind, a valid reason to run
64-bit DB2 on 32-bit AIX kernel (which is not to say IBM supports it -
my opinion should not be construed as IBM policy or even IBM opinion).
There are still some limitations of the 32- and 64-bit kernel, as I
understand it. One would be that kernel extentions (such as file
system drivers) can only run in a certain kernel - the one that matches
how it was compiled. (e.g., DB2 Datalinks Manager has a file system
driver which only runs 32-bit.) So, if you have such a driver from
another vendor, which prevents you from using the 64-bit kernel, but
you need access to all 8GB of RAM for DB2, you really have little
choice but to go into this "unsupported" realm.

Should you then have an actual problem to report to IBM, you may need
to reboot to 64-bit kernel (disabling the other software) to reproduce
and report it, so that your problem comes up in a "supported"
environment. But for the rest of the time, you run in the 32-bit
kernel.

[Buck Nuggets]

Jean-Marc,
AIX has a lot of flexibility here, and you're probably fine: there's a
difference between 32 & 64 bit user space, kernel, and hardware. So, I
believe that a 64-bit user process like db2 can run using either 32 or
64 bit kernel as long as it's on 64 bit hardware.

I think the main issue regarding the use of 64-bit db2 on 32-bit kernel
is not memory, but instead that registers will have to be converted to
32-bit. However, there may still be some other application software
that isn't yet 64-bit kernel ready (pssp?).

So, probably the best reason to go 64-bit kernel is to avoid register
conversions, and maybe to support jfs2? But I've run db2 on the 32-bit
kernel without any issues.
buck

[Larry]

Another possible scenario: migration from 32-bit to 64-bit, where you
are doing it in stages and the stage at 64-bit DB2 with 32-bit OS is
very temporary.

Larry Edelstein

Darin McBride wrote:

Jean-Marc Blaise wrote:

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:
Jean-Marc,

I believe what the technote is trying to say is you can install the
64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
once you install the DB2 binaries, you must create DB2 instances in
order to operate a DB2 database. I believe it is saying that you cannot
create 64-bit instances under a 32-bit OS. If you didn't receive an
error in attempting to do so, I guess you are in uncharted territory,
and risk not being able to get support from IBM. I'm not sure that
there's any advantage to using a 64-bit instance under a 32-bit OS,
even if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the
db2setup propose to create a 64-bit instance ? I think a 'bootinfo -K' can
be done to check if we are 32 or 64 bit kernel, and in case of 32-bit, it
should NOT propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,
but there must be a reason somewhere as AIX does support it.

I doubt it's "simulation" - I expect that since the processor can
handle 64-bit, the 32-bit kernel was just modified to allow 64-bit
programs to be controlled by it.

And why would db2setup allow 64-bit? Simple - users run all sorts of
unsupported scenarios. Many of them work. DB2 doesn't exactly want to
say it's smarter than the user when it can help it - if you really need
to run 64-bit on a 32-bit kernel, db2setup should not prevent it. This
is different from DB2's autonomic computing in that you can turn that
off. Since db2setup is run before you can configure DB2, it's hard to
turn off autonomic computing functionality there. It's a delicate line
which I'm sure db2setup jumps from side to side depending on the issue,
but we're definitely open to feedback about which side of the line
db2setup should be on for each issue.

Here's a scenario that would be, in my mind, a valid reason to run
64-bit DB2 on 32-bit AIX kernel (which is not to say IBM supports it -
my opinion should not be construed as IBM policy or even IBM opinion).
There are still some limitations of the 32- and 64-bit kernel, as I
understand it. One would be that kernel extentions (such as file
system drivers) can only run in a certain kernel - the one that matches
how it was compiled. (e.g., DB2 Datalinks Manager has a file system
driver which only runs 32-bit.) So, if you have such a driver from
another vendor, which prevents you from using the 64-bit kernel, but
you need access to all 8GB of RAM for DB2, you really have little
choice but to go into this "unsupported" realm.

Should you then have an actual problem to report to IBM, you may need
to reboot to 64-bit kernel (disabling the other software) to reproduce
and report it, so that your problem comes up in a "supported"
environment. But for the rest of the time, you run in the 32-bit
kernel.

[Jean-Marc Blaise]

Larry, there is no distinction between 32/64 bit from version 9i, it seems,
except from JVMs ... if I am right. :-)

JM

"Larry" <la***@nospam.net> a écrit dans le message de
news:Zz*******************@fe09.lga...

How do you know that Oracle supports it?

Larry Edelstein

Jean-Marc Blaise wrote:

"Jean-Marc Blaise" <no****@nowhere.com> a écrit dans le message de
news:42**********************@news.wanadoo.fr...

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:
>Jean-Marc,
>
>I believe what the technote is trying to say is you can install the
>64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
>once you install the DB2 binaries, you must create DB2 instances in
>order to operate a DB2 database. I believe it is saying that you

cannot

>create 64-bit instances under a 32-bit OS. If you didn't receive an
>error in attempting to do so, I guess you are in uncharted territory,
>and risk not being able to get support from IBM. I'm not sure that
>there's any advantage to using a 64-bit instance under a 32-bit OS,

even

>if you are able to get it to work and it even if it IS supported.

My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the

db2setup

propose to create a 64-bit instance ? I think a 'bootinfo -K' can be done

to

check if we are 32 or 64 bit kernel, and in case of 32-bit, it should

NOTpropose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel,but there must be a reason somewhere as AIX does support it.

Best regards,

Jean-Marc

.... By the way, it seems Oracle installs in 64-bit only on such

machines ... so why would DB2 avoid this support ?

[Jean-Marc Blaise]

Darin, Larry and Buck, thank you very much for sharing your thoughts...

Jean-Marc

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:tq6Md.251654$8l.20054@pd7tw1no...

Jean-Marc Blaise wrote:

"Darin McBride" <dm******@naboo.to.org.no.spam.for.me> a écrit dans le
message de news:T0ZLd.250407$Xk.6730@pd7tw3no...

Larry E wrote:

> Jean-Marc,
>
> I believe what the technote is trying to say is you can install the
> 64-bit version of DB2 (i.e. the DB2 binaries) under a 32-bit OS, but
> once you install the DB2 binaries, you must create DB2 instances in
> order to operate a DB2 database. I believe it is saying that you cannot > create 64-bit instances under a 32-bit OS. If you didn't receive an
> error in attempting to do so, I guess you are in uncharted territory,
> and risk not being able to get support from IBM. I'm not sure that
> there's any advantage to using a 64-bit instance under a 32-bit OS,
> even if you are able to get it to work and it even if it IS supported.
My understanding is that AIX is a special case in that it works.
However, I don't think it's officially supported. I'm not sure if this
is explicitly unsupported, or simply implicitly unsupported by the fact
that the combination is not documented to be supported.

Hi Darin,

Thanks for your reply. This is not really clear to me; why does the
db2setup propose to create a 64-bit instance ? I think a 'bootinfo -K' can be done to check if we are 32 or 64 bit kernel, and in case of 32-bit, it should NOT propose to create a 64-bit instance, don't you think so ?

I agree that it seems crazy to do 64-bit "simulation" on a 32-bit kernel, but there must be a reason somewhere as AIX does support it.

I doubt it's "simulation" - I expect that since the processor can
handle 64-bit, the 32-bit kernel was just modified to allow 64-bit
programs to be controlled by it.

And why would db2setup allow 64-bit? Simple - users run all sorts of
unsupported scenarios. Many of them work. DB2 doesn't exactly want to
say it's smarter than the user when it can help it - if you really need
to run 64-bit on a 32-bit kernel, db2setup should not prevent it. This
is different from DB2's autonomic computing in that you can turn that
off. Since db2setup is run before you can configure DB2, it's hard to
turn off autonomic computing functionality there. It's a delicate line
which I'm sure db2setup jumps from side to side depending on the issue,
but we're definitely open to feedback about which side of the line
db2setup should be on for each issue.

Here's a scenario that would be, in my mind, a valid reason to run
64-bit DB2 on 32-bit AIX kernel (which is not to say IBM supports it -
my opinion should not be construed as IBM policy or even IBM opinion).
There are still some limitations of the 32- and 64-bit kernel, as I
understand it. One would be that kernel extentions (such as file
system drivers) can only run in a certain kernel - the one that matches
how it was compiled. (e.g., DB2 Datalinks Manager has a file system
driver which only runs 32-bit.) So, if you have such a driver from
another vendor, which prevents you from using the 64-bit kernel, but
you need access to all 8GB of RAM for DB2, you really have little
choice but to go into this "unsupported" realm.

Should you then have an actual problem to report to IBM, you may need
to reboot to 64-bit kernel (disabling the other software) to reproduce
and report it, so that your problem comes up in a "supported"
environment. But for the rest of the time, you run in the 32-bit
kernel.

[Buck Nuggets]

follow-up:

on page 333 of the snappily-named redbook "DB2 UDB ESE V8 non-DPF
Performance Guide for High Performance OLTP and BI"
(http://www.redbooks.ibm.com/redbooks/pdfs/sg246432.pdf)
it says specifically that db2 64-bit can run on aix 32-bit kernels.
buck

[Jean-Marc Blaise]

Thanks Buck,

Around the same page, it is written that you should better use 64-bit
version rather than extended memory for bufferpools, that has limitation. So
I guess this could be one good reason to use a 64-bit instance on a 32-bit
kernel (due to other soft limitations).

Cheers,

JM

"Buck Nuggets" <bu*********@yahoo.com> a écrit dans le message de
news:11**********************@z14g2000cwz.googlegr oups.com...

follow-up:

on page 333 of the snappily-named redbook "DB2 UDB ESE V8 non-DPF
Performance Guide for High Performance OLTP and BI"
(http://www.redbooks.ibm.com/redbooks/pdfs/sg246432.pdf)
it says specifically that db2 64-bit can run on aix 32-bit kernels.
buck