[Pound Mailing List] Can multiple pound servers connect to the same zope server instance and port?

[Jamie Robe]

Hi. I have a pound server in my DMZ connecting to several zope client
servers inside my LAN (for scalability and redundancy). I currently have
an Intranet site running only inside the LAN (on its own zope/plone
instance) on ONE of the servers. My question is, can I add a pound
server inside the LAN (for Intranet redundancy) and attach to the same
zope instances (ports) on my internal zope servers as the outside pound
server? Will this cause any problems?

My question really is, can I avoid having to run special parallel zope
instances on two different ports to make this work? It is a pain to
maintain products, etc, when they all use the same products, etc.

My crude diagram of how it is now is below:

Internet
|
pound1:80
/ \
firewall....... /......\.............
/ \
zope1:1000 zope2:1000
Intranet---zope1:1001


I want to run a second pound server pound2, that will connect to
zope1:1000 and zope2:1000, thereby giving me redundancy (I could
shutdown instance zope1:1001)...

Or do I have to create and maintain two more instances, zope1:1001 and
zope2:1001

Thanks

Jamie T. Robe
Automation Team Leader
The Planning Commission
[phone]
http://www.theplanningcommission.org

[Ted Dunning]

Running a second pound is no problem at all.

It won't provide a truly redundant capability because the two pounds don't
share session state. That means whenever you fail-over to the other one,
you will lose any live session information.

If you are routing based on source IP, this may not be much of a problem.

Post by Jamie Robe
Hi. I have a pound server in my DMZ connecting to several zope client
servers inside my LAN (for scalability and redundancy). I currently have
an Intranet site running only inside the LAN (on its own zope/plone
instance) on ONE of the servers. My question is, can I add a pound
server inside the LAN (for Intranet redundancy) and attach to the same
zope instances (ports) on my internal zope servers as the outside pound
server? Will this cause any problems?
My question really is, can I avoid having to run special parallel zope
instances on two different ports to make this work? It is a pain to
maintain products, etc, when they all use the same products, etc.
Internet
|
pound1:80
/ \
firewall....... /......\.............
/ \
zope1:1000 zope2:1000
Intranet---zope1:1001
I want to run a second pound server pound2, that will connect to
zope1:1000 and zope2:1000, thereby giving me redundancy (I could
shutdown instance zope1:1001)...
Or do I have to create and maintain two more instances, zope1:1001 and
zope2:1001
Thanks
Jamie T. Robe
Automation Team Leader
The Planning Commission
[phone]
http://www.theplanningcommission.org
--
http://www.apsis.ch/pound/pound_list/archive/2006/2006-11/1163625905000

[John Snowdon]

One way round that problem is to make Zope hold the session data. It
does by default, but isn't able to share the session information with
subsequent Zope servers. The answer is to move the session information
(which is normally held inside /temp_folder) into a data.fs and mount it
via ZEO in all Zope servers running that particular application.

A nice side effect is that Pound no longer has to track the incoming
connections and you get a smoother spread of requests (e.g individual
page elements).

We use this extensively and it's usually fine. We have found some
applications though, particulary those that do a lot of session.set and
session.get can very occaisionaly corrupt the session folder - in those
situations the transient object container needs to be deleted and then
added again (this can be done on-line). Of course we are still using
2.7.2 across the board - the behaviour may be better on the more modern
versions.

John Snowdon - IT Support Specialist
-==========================================-
School of Medical Education Development
Faculty of Medical Sciences Computing
University of Newcastle

-----Original Message-----
Sent: 15 November 2006 21:59
Subject: Re: [Pound Mailing List] Can multiple pound servers
connect to the same zope server instance and port?
Running a second pound is no problem at all.
It won't provide a truly redundant capability because the two
pounds don't
share session state. That means whenever you fail-over to the
other one,
you will lose any live session information.
If you are routing based on source IP, this may not be much of
a problem.

Post by Jamie Robe
Hi. I have a pound server in my DMZ connecting to several zope client
servers inside my LAN (for scalability and redundancy). I

currently have

Post by Jamie Robe
an Intranet site running only inside the LAN (on its own zope/plone
instance) on ONE of the servers. My question is, can I add a pound
server inside the LAN (for Intranet redundancy) and attach

to the same

Post by Jamie Robe
zope instances (ports) on my internal zope servers as the

outside pound

Post by Jamie Robe
server? Will this cause any problems?
My question really is, can I avoid having to run special

parallel zope

Post by Jamie Robe
instances on two different ports to make this work? It is a pain to
maintain products, etc, when they all use the same products, etc.
Internet
|
pound1:80
/ \
firewall....... /......\.............
/ \
zope1:1000 zope2:1000
Intranet---zope1:1001
I want to run a second pound server pound2, that will connect to
zope1:1000 and zope2:1000, thereby giving me redundancy (I could
shutdown instance zope1:1001)...
Or do I have to create and maintain two more instances,

zope1:1001 and

Post by Jamie Robe
zope2:1001
Thanks
Jamie T. Robe
Automation Team Leader
The Planning Commission
[phone]
http://www.theplanningcommission.org
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[Robert Segall]

Post by John Snowdon
We use this extensively and it's usually fine. We have found some
applications though, particulary those that do a lot of session.set and
session.get can very occaisionaly corrupt the session folder - in those
situations the transient object container needs to be deleted and then
added again (this can be done on-line). Of course we are still using
2.7.2 across the board - the behaviour may be better on the more modern
versions.

You may want to look at the newer versions. With the latest ZODB (with
MVCC) you may see fewer problems.
--
Robert Segall
Apsis GmbH
Postfach, Uetikon am See, CH-8707
Tel: [phone]

[John Snowdon]

Because any upgrade of Zope would have to be across the board for us
(we've got approx 100 applications running across our server farm),
we're actually looking at alternative frameworks at the moment;
turbogears, django and ruby. In any case we probably won't go to Zope 3
- the next update we do will most likely be our last Zope 2
installation; at the moment it's looking like 2.10 would be the final
stepping stone.

My biggest bug bear with the other frameworks is the lack of enterprise
level features exactly like ZEO....

John Snowdon - IT Support Specialist
-==========================================-
School of Medical Education Development
Faculty of Medical Sciences Computing
University of Newcastle

-----Original Message-----
Sent: 16 November 2006 17:55
Subject: RE: [Pound Mailing List] Can multiple pound servers
connect to the same zope server instance and port?

Post by John Snowdon
We use this extensively and it's usually fine. We have found some
applications though, particulary those that do a lot of

session.set and

Post by John Snowdon
session.get can very occaisionaly corrupt the session folder

- in those

Post by John Snowdon
situations the transient object container needs to be

deleted and then

Post by John Snowdon
added again (this can be done on-line). Of course we are still using
2.7.2 across the board - the behaviour may be better on the

more modern

Post by John Snowdon
versions.

You may want to look at the newer versions. With the latest ZODB (with
MVCC) you may see fewer problems.
--
Robert Segall
Apsis GmbH
Postfach, Uetikon am See, CH-8707
Tel: [phone]
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25905000/1163699696000

[Malte Ahrens]

Of course you can use multiple pound server connecting to the same
webserver. From the point of the web server pound acts as a client - and
I guess most web servers on the world can handle more than one client :-)

Malte

Post by Jamie Robe
Hi. I have a pound server in my DMZ connecting to several zope client
servers inside my LAN (for scalability and redundancy). I currently have
an Intranet site running only inside the LAN (on its own zope/plone
instance) on ONE of the servers. My question is, can I add a pound
server inside the LAN (for Intranet redundancy) and attach to the same
zope instances (ports) on my internal zope servers as the outside pound
server? Will this cause any problems?
My question really is, can I avoid having to run special parallel zope
instances on two different ports to make this work? It is a pain to
maintain products, etc, when they all use the same products, etc.
Internet
|
pound1:80
/ \
firewall....... /......\.............
/ \
zope1:1000 zope2:1000
Intranet---zope1:1001
I want to run a second pound server pound2, that will connect to
zope1:1000 and zope2:1000, thereby giving me redundancy (I could
shutdown instance zope1:1001)...
Or do I have to create and maintain two more instances, zope1:1001 and
zope2:1001
Thanks
Jamie T. Robe
Automation Team Leader
The Planning Commission
[phone]
http://www.theplanningcommission.org