Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Cal Leeming [Simplicity Media Ltd]]

Just to chime in on this..

In terms of commercial options, we have sometimes gone with ZXTM (now known
as StingRay Traffic Manager) , it has some truly amazing features and you
should definitely check it out. I believe that RiverBed have since started
issuing free commercial licences for up to a certain traffic rate, and it's
a downloadable package/virtual appliance.

We also often use the load balancers that come with Rackspace Cloud, they
have proven to be quite efficient. When using this route, we also tend to
throw everything in front of CloudFlare too (if you haven't seen this
already, check it out. It is free for non SSL usage too!)

In a nut shell;

* ZXTM - commercial (free licence to a certain amount), amazing traffic
script language, self hosted
* Rackspace Cloud - does what it says on the tin, no traffic scripting
* F5 - commercial, not had any personal experience with it (but one of our
providers uses it as a shared load balancer for their customers and it's
been stable)
* haproxy - works, but it can be a pita!
* CloudFlare - this isn't a load balancer, but does give you much better
control over DNS (it proxies your site, and effectively makes 'DNS changes'
instant)

I believe uWSGI has some really good load balancing features too, but I
haven't used them in too much depth yet (despite being an avid user of
uWSGI for 2-3 years!)

Hope this helps

Cal

On Tue, Oct 30, 2012 at 8:14 AM, Kurtis Mullins wrote:

> The easiest thing I've found to use is simply uWSGI with Nginx. It's easy
> to just create new Django servers on the fly. You simply include the IPs in
> a list and it will use various algorithms (optional) to distribute the
> requests appropriately.
>
> As a lot of applications are IO bound, you could also use a distributed
> database system to help with your scalability. I don't have much experience
> in that area, though.
>
> This still leaves a point of failure: Nginx (or whatever load balancer or
> reverse proxy you use). Maybe someone else here will know more about load
> balancing Nginx itself ... that might require specialized hardware. I know
> a lot of cloud services offer load balancers (e.g. rackspace) so you could
> possibly use that with multiple nginx servers and further multiple django
> servers.
>
>
> On Tue, Oct 30, 2012 at 3:42 AM, Isaac XXX  wrote:
>
>> Hi there,
>>
>> maybe you're right, but I'm not really worried about RAM footprint, or
>> resources consumption. I'm concerned now on architecture, setting a right
>> scalable system, and a right cluster of systems, without lacks of
>> communications between them.
>>
>> Underlaying technologies can be easily replaced (say apache-mod_wsgi for
>> gunicorn or uwsgi), and some performance improvements can be made, but this
>> is not what I'm looking for. I'm looking for the tools to generate a robust
>> system, balancing requests through several systems, and allowing increase
>> the size of this system (adding more servers) without trouble.
>>
>> Cheers,
>>
>> Isaac
>>
>>
>> On 10/29/2012 05:18 PM, Some Developer wrote:
>>
>>> On 29/10/2012 16:03, Isaac XXX wrote:
>>>
 Hi there,

 thank you for response Tom.

 Actually, I've a complete idea at how to build this system, but I lack
 the exact information about how to join systems, and what I was looking for
 was a source of cohesive information on all systems. At least, when I
 finish to build that system, I will write this tutorial.

 For someone who can help me, I will describe here what I thought it can
 be this structure:

 - 1 nginx, as a reverse proxy on frontend, serving static/media and
 redirecting content to apache clusters
 - n apache servers, with mod_wsgi, serving dynamic data
 - m postgresql servers, in a master-slave flavour

 Cheers,

 Isaac

>>>
>>> Why not just ditch Apache entirely and just use Nginx for serving all
>>> media (both static and dynamic)? You can then save quite a few resources as
>>> you only need to run one HTTP server rather than two.
>>>
>>> Using Nginx to serve Django content works well. Just serve your Django
>>> application via FastCGI or uWSGI and you'll significantly simplify your
>>> configuration and reduce RAM usage on your servers as well.
>>>
>>>
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>> .
>>
>>
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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Tom Evans]

On Tue, Oct 30, 2012 at 7:35 AM, Isaac XXX  wrote:
> Hi Tom,
>
> you're right, I was not really explicit about what were my lacks of
> information. Right now, the following points are the ones I can't found a
> howto for the desired deployment:
>
> - Create a master-slave system on postgresql, maintaining all systems up to
> date, distributing reads, and centralizing writes
> - How to configure a cluster of reverse proxies (a single reverse proxy can
> not be enought, and I need to plan to deploy more than 1 load balancers)
>
> The rest (configure apache with mod_wsgit, configure nginx to serve static
> content and so on), is now solved on my current deployments, so it should
> not be a problem on a distributed environment.
>
> Cheers,
>
> Isaac
>

Hi Isaac

We use a similar setup at $JOB. We run a pair of apache httpd servers,
which serve static content and reverse proxy to other http servers
(usually apache again, sometimes not) for dynamic content. The
requests are distributed evenly between the two proxies by our
routers, which round robin connections between the two of them. This
is basically your setup, but we use Apache, because we know it and can
tune it to give nginx like performance anyway.

Actually, that's only half of it - each proxy has all of the public
IPs we serve allocated on lo0 (loopback), and the requests are round
robin routed via a pair of high availability addresses. Therefore, on
both boxes, apache listens on the 'right' IPs. If we ever want to run
with just one proxy, we can 'down' one of the HA addresses on the
server we wish to update, which moves that HA address to be active on
the other proxy, which then serves all the requests.

Now, did we need to do any of this? Probably not! We serve in the
region of 3-5 million requests a day, with peaks of around 200
concurrent requests/s going through the proxies. Apache uses in total
500MB of RAM, pre-tuned to serve up to 768 concurrent req/s without
requiring extra resources. Load average on the boxes never goes above
0.05, even if we put all the requests through one machine. It's nice
having a spare for such a critical part of infrastructure though.

pgsql scaling is a little more involved than MySQL, which is what
we've always used here - usually because it's replication systems are
so good. You will typically need to use some external software to
manage the replication, eg Slony, but don't take my word for it, very
limited pgsql experience.

Cheers

Tom

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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Kurtis Mullins]

The easiest thing I've found to use is simply uWSGI with Nginx. It's easy
to just create new Django servers on the fly. You simply include the IPs in
a list and it will use various algorithms (optional) to distribute the
requests appropriately.

As a lot of applications are IO bound, you could also use a distributed
database system to help with your scalability. I don't have much experience
in that area, though.

This still leaves a point of failure: Nginx (or whatever load balancer or
reverse proxy you use). Maybe someone else here will know more about load
balancing Nginx itself ... that might require specialized hardware. I know
a lot of cloud services offer load balancers (e.g. rackspace) so you could
possibly use that with multiple nginx servers and further multiple django
servers.

On Tue, Oct 30, 2012 at 3:42 AM, Isaac XXX  wrote:

> Hi there,
>
> maybe you're right, but I'm not really worried about RAM footprint, or
> resources consumption. I'm concerned now on architecture, setting a right
> scalable system, and a right cluster of systems, without lacks of
> communications between them.
>
> Underlaying technologies can be easily replaced (say apache-mod_wsgi for
> gunicorn or uwsgi), and some performance improvements can be made, but this
> is not what I'm looking for. I'm looking for the tools to generate a robust
> system, balancing requests through several systems, and allowing increase
> the size of this system (adding more servers) without trouble.
>
> Cheers,
>
> Isaac
>
>
> On 10/29/2012 05:18 PM, Some Developer wrote:
>
>> On 29/10/2012 16:03, Isaac XXX wrote:
>>
>>> Hi there,
>>>
>>> thank you for response Tom.
>>>
>>> Actually, I've a complete idea at how to build this system, but I lack
>>> the exact information about how to join systems, and what I was looking for
>>> was a source of cohesive information on all systems. At least, when I
>>> finish to build that system, I will write this tutorial.
>>>
>>> For someone who can help me, I will describe here what I thought it can
>>> be this structure:
>>>
>>> - 1 nginx, as a reverse proxy on frontend, serving static/media and
>>> redirecting content to apache clusters
>>> - n apache servers, with mod_wsgi, serving dynamic data
>>> - m postgresql servers, in a master-slave flavour
>>>
>>> Cheers,
>>>
>>> Isaac
>>>
>>
>> Why not just ditch Apache entirely and just use Nginx for serving all
>> media (both static and dynamic)? You can then save quite a few resources as
>> you only need to run one HTTP server rather than two.
>>
>> Using Nginx to serve Django content works well. Just serve your Django
>> application via FastCGI or uWSGI and you'll significantly simplify your
>> configuration and reduce RAM usage on your servers as well.
>>
>>
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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Isaac XXX]

Hi there,

maybe you're right, but I'm not really worried about RAM footprint, or 
resources consumption. I'm concerned now on architecture, setting a 
right scalable system, and a right cluster of systems, without lacks of 
communications between them.


Underlaying technologies can be easily replaced (say apache-mod_wsgi for 
gunicorn or uwsgi), and some performance improvements can be made, but 
this is not what I'm looking for. I'm looking for the tools to generate 
a robust system, balancing requests through several systems, and 
allowing increase the size of this system (adding more servers) without 
trouble.


Cheers,

Isaac

On 10/29/2012 05:18 PM, Some Developer wrote:

On 29/10/2012 16:03, Isaac XXX wrote:

Hi there,

thank you for response Tom.

Actually, I've a complete idea at how to build this system, but I 
lack the exact information about how to join systems, and what I was 
looking for was a source of cohesive information on all systems. At 
least, when I finish to build that system, I will write this tutorial.


For someone who can help me, I will describe here what I thought it 
can be this structure:


- 1 nginx, as a reverse proxy on frontend, serving static/media and 
redirecting content to apache clusters

- n apache servers, with mod_wsgi, serving dynamic data
- m postgresql servers, in a master-slave flavour

Cheers,

Isaac


Why not just ditch Apache entirely and just use Nginx for serving all 
media (both static and dynamic)? You can then save quite a few 
resources as you only need to run one HTTP server rather than two.


Using Nginx to serve Django content works well. Just serve your Django 
application via FastCGI or uWSGI and you'll significantly simplify 
your configuration and reduce RAM usage on your servers as well.




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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Isaac XXX]

Thank you so much for tips. I will keep them when I start to test 
environment for performance.


Cheers

Isaac

On 10/29/2012 06:44 PM, Cal Leeming [Simplicity Media Ltd] wrote:

Hi Isaac,

If there is one thing I have learnt about scaling apps, it's about 
trying things out for yourself.


Sure there are some best practice guidelines (i.e. serving files from 
nginx, or using apache's X-SendFile rather than streaming out via the 
webapp), but if someone comes along and tells you to use X instead of 
Y, then you don't get the advantages of learning "the hard way".


Another important note is that scaling rarely goes up on a 1:1 ratio, 
i.e. the configuration and resources required to handle X number of 
requests/sec, may be completely different if you need to handle Y 
number of requests/sec.


And often what works for one person, won't work for another (scaling 
is entirely dependant on your application, despite what any of these 
cloud providers might tell you!)


In my own experience, I've found that;

* SSDs with Percona MySQL, resolves a LOT of performance problems - 
but don't abuse it

* Lots and lots and lots of query tuning and InnoDB tuning
* New Relic to identify bottlenecks
* IO contention is a big thing
* Snowball prevention (i.e. you set max clients to X, your backend 
can't handle it, your requests stack up, the load balancer forces time 
out, and your database gets smashed - or you set max memory too high, 
server goes into swap etc).

* uWSGI + nginx is amazing
* Identify where your bottlenecks are (in my own experience, IO/memory 
tends to come up more often than CPU)


Sadly I haven't tried PSQL so I can't offer any advice on this - 
Percona are dragging MySQL kicking and screaming into the 21st century 
and really doing some amazing things, but it's by no means perfect!


The above has helped us grow past 8k-12k requests/minute, the largest 
database we manage is around 1.1 billion rows weighing in at 160GB+, 
and we maintain around 60+ servers.


I should reiterate, the above is purely based on my own experience and 
use cases - I am by no means an expert on the subject and I'm still 
learning approaches on a daily basis - so this is really meant as 
"food for thought" rather than a "this is how you should do things".


Hope this helps a bit!

Cal

On Mon, Oct 29, 2012 at 2:42 PM, Isaac XXX > wrote:


Hi folks,

I'm developing a new application that should get high traffic.
Right now, I've other projects with the follow architecture:

Nginx on front: serving static content and redirecting to apache
for dynamic data
Apache+mod_wsgi: serving dynamic pages
PostgreSQL: backend for data storage (RDBM)
Memcache: for caching purposes :)

All my deployments use a single server, with single
frontend/backend (1 nginx, 1 apache, 1 postgresql). The
requirements for this new project are really large, and I think I
will need to scale all system. Can anyone suggest me an all-in-one
tutorial, discussing the main points on scale a system?

I know there are different alternatives for DB (master-slave,
clustering...), nginx can serve as a reverse proxy or not... and I
need to merge all this information in a single scalable system,
but I can't find an unified source of information.

Can anyone help me on it?

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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Isaac XXX]

Hi Tom,

you're right, I was not really explicit about what were my lacks of 
information. Right now, the following points are the ones I can't found 
a howto for the desired deployment:


- Create a master-slave system on postgresql, maintaining all systems up 
to date, distributing reads, and centralizing writes
- How to configure a cluster of reverse proxies (a single reverse proxy 
can not be enought, and I need to plan to deploy more than 1 load balancers)


The rest (configure apache with mod_wsgit, configure nginx to serve 
static content and so on), is now solved on my current deployments, so 
it should not be a problem on a distributed environment.


Cheers,

Isaac

On 10/29/2012 05:23 PM, Tom Evans wrote:

On Mon, Oct 29, 2012 at 4:03 PM, Isaac XXX  wrote:

Hi there,

thank you for response Tom.

Actually, I've a complete idea at how to build this system, but I lack the
exact information about how to join systems, and what I was looking for was
a source of cohesive information on all systems. At least, when I finish to
build that system, I will write this tutorial.

For someone who can help me, I will describe here what I thought it can be
this structure:

- 1 nginx, as a reverse proxy on frontend, serving static/media and
redirecting content to apache clusters
- n apache servers, with mod_wsgi, serving dynamic data
- m postgresql servers, in a master-slave flavour

Cheers,

Isaac


I'm confused about what you are confused about - you seem to grasp
precisely what is required.

IE, which of the following Qs are you stuck at:

How to configure nginx to reverse proxy and balance to other http servers?
How to configure apache, mod_wsgi and django?
How to configure pgsql in a master/multiple slave environment?
How to configure django to issue write requests to the write master,
and distribute reads to read-only slaves?


Cheers

Tom



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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Kurtis Mullins]

The old rule of thumb is to avoid premature optimization. I'd build,
profile, then scale or otherwise optimize as needed. This isn't a tutorial
or really a discussion on all points of scaling a system; but identifying
bottle necks will do wonders when it comes to deciding what, where, and how
to scale. Good luck!

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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Cal Leeming [Simplicity Media Ltd]]

Hi Isaac,

If there is one thing I have learnt about scaling apps, it's about trying
things out for yourself.

Sure there are some best practice guidelines (i.e. serving files from
nginx, or using apache's X-SendFile rather than streaming out via the
webapp), but if someone comes along and tells you to use X instead of Y,
then you don't get the advantages of learning "the hard way".

Another important note is that scaling rarely goes up on a 1:1 ratio, i.e.
the configuration and resources required to handle X number of
requests/sec, may be completely different if you need to handle Y number of
requests/sec.

And often what works for one person, won't work for another (scaling is
entirely dependant on your application, despite what any of these cloud
providers might tell you!)

In my own experience, I've found that;

* SSDs with Percona MySQL, resolves a LOT of performance problems - but
don't abuse it
* Lots and lots and lots of query tuning and InnoDB tuning
* New Relic to identify bottlenecks
* IO contention is a big thing
* Snowball prevention (i.e. you set max clients to X, your backend can't
handle it, your requests stack up, the load balancer forces time out, and
your database gets smashed - or you set max memory too high, server goes
into swap etc).
* uWSGI + nginx is amazing
* Identify where your bottlenecks are (in my own experience, IO/memory
tends to come up more often than CPU)

Sadly I haven't tried PSQL so I can't offer any advice on this - Percona
are dragging MySQL kicking and screaming into the 21st century and really
doing some amazing things, but it's by no means perfect!

The above has helped us grow past 8k-12k requests/minute, the largest
database we manage is around 1.1 billion rows weighing in at 160GB+, and we
maintain around 60+ servers.

I should reiterate, the above is purely based on my own experience and use
cases - I am by no means an expert on the subject and I'm still learning
approaches on a daily basis - so this is really meant as "food for thought"
rather than a "this is how you should do things".

Hope this helps a bit!

Cal

On Mon, Oct 29, 2012 at 2:42 PM, Isaac XXX  wrote:

> Hi folks,
>
> I'm developing a new application that should get high traffic. Right now,
> I've other projects with the follow architecture:
>
> Nginx on front: serving static content and redirecting to apache for
> dynamic data
> Apache+mod_wsgi: serving dynamic pages
> PostgreSQL: backend for data storage (RDBM)
> Memcache: for caching purposes :)
>
> All my deployments use a single server, with single frontend/backend (1
> nginx, 1 apache, 1 postgresql). The requirements for this new project are
> really large, and I think I will need to scale all system. Can anyone
> suggest me an all-in-one tutorial, discussing the main points on scale a
> system?
>
> I know there are different alternatives for DB (master-slave,
> clustering...), nginx can serve as a reverse proxy or not... and I need to
> merge all this information in a single scalable system, but I can't find an
> unified source of information.
>
> Can anyone help me on it?
>
> --
> You received this message because you are subscribed to the Google Groups
> "Django users" group.
> To post to this group, send email to django-users@googlegroups.com.
> To unsubscribe from this group, send email to django-users+unsubscribe@**
> googlegroups.com .
> For more options, visit this group at http://groups.google.com/**
> group/django-users?hl=en
> .
>
>

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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Some Developer]

On 29/10/2012 16:03, Isaac XXX wrote:

Hi there,

thank you for response Tom.

Actually, I've a complete idea at how to build this system, but I lack 
the exact information about how to join systems, and what I was 
looking for was a source of cohesive information on all systems. At 
least, when I finish to build that system, I will write this tutorial.


For someone who can help me, I will describe here what I thought it 
can be this structure:


- 1 nginx, as a reverse proxy on frontend, serving static/media and 
redirecting content to apache clusters

- n apache servers, with mod_wsgi, serving dynamic data
- m postgresql servers, in a master-slave flavour

Cheers,

Isaac


Why not just ditch Apache entirely and just use Nginx for serving all 
media (both static and dynamic)? You can then save quite a few resources 
as you only need to run one HTTP server rather than two.


Using Nginx to serve Django content works well. Just serve your Django 
application via FastCGI or uWSGI and you'll significantly simplify your 
configuration and reduce RAM usage on your servers as well.


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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Tom Evans]

On Mon, Oct 29, 2012 at 4:03 PM, Isaac XXX  wrote:
> Hi there,
>
> thank you for response Tom.
>
> Actually, I've a complete idea at how to build this system, but I lack the
> exact information about how to join systems, and what I was looking for was
> a source of cohesive information on all systems. At least, when I finish to
> build that system, I will write this tutorial.
>
> For someone who can help me, I will describe here what I thought it can be
> this structure:
>
> - 1 nginx, as a reverse proxy on frontend, serving static/media and
> redirecting content to apache clusters
> - n apache servers, with mod_wsgi, serving dynamic data
> - m postgresql servers, in a master-slave flavour
>
> Cheers,
>
> Isaac
>

I'm confused about what you are confused about - you seem to grasp
precisely what is required.

IE, which of the following Qs are you stuck at:

How to configure nginx to reverse proxy and balance to other http servers?
How to configure apache, mod_wsgi and django?
How to configure pgsql in a master/multiple slave environment?
How to configure django to issue write requests to the write master,
and distribute reads to read-only slaves?


Cheers

Tom

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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Isaac XXX]

Hi there,

thank you for response Tom.

Actually, I've a complete idea at how to build this system, but I lack 
the exact information about how to join systems, and what I was looking 
for was a source of cohesive information on all systems. At least, when 
I finish to build that system, I will write this tutorial.


For someone who can help me, I will describe here what I thought it can 
be this structure:


- 1 nginx, as a reverse proxy on frontend, serving static/media and 
redirecting content to apache clusters

- n apache servers, with mod_wsgi, serving dynamic data
- m postgresql servers, in a master-slave flavour

Cheers,

Isaac

On 10/29/2012 04:23 PM, Tom Evans wrote:

On Mon, Oct 29, 2012 at 2:42 PM, Isaac XXX  wrote:

Hi folks,

I'm developing a new application that should get high traffic. Right now,
I've other projects with the follow architecture:

Nginx on front: serving static content and redirecting to apache for dynamic
data
Apache+mod_wsgi: serving dynamic pages
PostgreSQL: backend for data storage (RDBM)
Memcache: for caching purposes :)

All my deployments use a single server, with single frontend/backend (1
nginx, 1 apache, 1 postgresql). The requirements for this new project are
really large, and I think I will need to scale all system. Can anyone
suggest me an all-in-one tutorial, discussing the main points on scale a
system?

I know there are different alternatives for DB (master-slave,
clustering...), nginx can serve as a reverse proxy or not... and I need to
merge all this information in a single scalable system, but I can't find an
unified source of information.

Can anyone help me on it?


There is unlikely to be one authoritative source that will explain
precisely how to scale an app - part of this is it is domain specific
what "scale" and "app" mean!

So first off, "scale". You can scale up, or out. Scaling up means
running everything on faster hardware. Due to how IT progresses, every
18 months you can replace your server with something twice as fast.
Scale out means running everything over more boxes. Scale up is
trivial, just spend more money, scale out can be harder.

Most parts of the stack are easy to scale, because HTTP itself is
stateless and therefore easy to scale. Eg, if you have a nginx
frontend, serving static files and proxying to backend servers for
static content, and the nginx server is overloaded, it is easy to add
a balancer to route HTTP requests to multiple nginx servers.

The same is true for dynamic content - need more workers, add more
machines, and tell nginx to talk to more machines.

The only tricky aspect of scale out is database. Most databases do not
have a simple 'scale out' option. With postgres, you can setup
master-slave trees, but this only expands your read capacity, all
writes have to go through one server (and then all the slaves, making
it more expensive the more slaves you add).

The only true way of scaling out with database servers is to shard
your data, splitting it up by some arbitrary algorithm (usually on
user), but sharding isn't easy, you will have to design your database
and app around it. There are some very good videos, docs and talks
from the likes of Facebook and the like, sharding is not a panacea and
requires a lot of work.

Cheers

Tom



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Re: Scaling django (nginx + apache + mod_wsgi + postgresql)

[Tom Evans]

On Mon, Oct 29, 2012 at 2:42 PM, Isaac XXX  wrote:
> Hi folks,
>
> I'm developing a new application that should get high traffic. Right now,
> I've other projects with the follow architecture:
>
> Nginx on front: serving static content and redirecting to apache for dynamic
> data
> Apache+mod_wsgi: serving dynamic pages
> PostgreSQL: backend for data storage (RDBM)
> Memcache: for caching purposes :)
>
> All my deployments use a single server, with single frontend/backend (1
> nginx, 1 apache, 1 postgresql). The requirements for this new project are
> really large, and I think I will need to scale all system. Can anyone
> suggest me an all-in-one tutorial, discussing the main points on scale a
> system?
>
> I know there are different alternatives for DB (master-slave,
> clustering...), nginx can serve as a reverse proxy or not... and I need to
> merge all this information in a single scalable system, but I can't find an
> unified source of information.
>
> Can anyone help me on it?
>

There is unlikely to be one authoritative source that will explain
precisely how to scale an app - part of this is it is domain specific
what "scale" and "app" mean!

So first off, "scale". You can scale up, or out. Scaling up means
running everything on faster hardware. Due to how IT progresses, every
18 months you can replace your server with something twice as fast.
Scale out means running everything over more boxes. Scale up is
trivial, just spend more money, scale out can be harder.

Most parts of the stack are easy to scale, because HTTP itself is
stateless and therefore easy to scale. Eg, if you have a nginx
frontend, serving static files and proxying to backend servers for
static content, and the nginx server is overloaded, it is easy to add
a balancer to route HTTP requests to multiple nginx servers.

The same is true for dynamic content - need more workers, add more
machines, and tell nginx to talk to more machines.

The only tricky aspect of scale out is database. Most databases do not
have a simple 'scale out' option. With postgres, you can setup
master-slave trees, but this only expands your read capacity, all
writes have to go through one server (and then all the slaves, making
it more expensive the more slaves you add).

The only true way of scaling out with database servers is to shard
your data, splitting it up by some arbitrary algorithm (usually on
user), but sharding isn't easy, you will have to design your database
and app around it. There are some very good videos, docs and talks
from the likes of Facebook and the like, sharding is not a panacea and
requires a lot of work.

Cheers

Tom

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Scaling django (nginx + apache + mod_wsgi + postgresql)

[Isaac XXX]

Hi folks,

I'm developing a new application that should get high traffic. Right 
now, I've other projects with the follow architecture:


Nginx on front: serving static content and redirecting to apache for 
dynamic data

Apache+mod_wsgi: serving dynamic pages
PostgreSQL: backend for data storage (RDBM)
Memcache: for caching purposes :)

All my deployments use a single server, with single frontend/backend (1 
nginx, 1 apache, 1 postgresql). The requirements for this new project 
are really large, and I think I will need to scale all system. Can 
anyone suggest me an all-in-one tutorial, discussing the main points on 
scale a system?


I know there are different alternatives for DB (master-slave, 
clustering...), nginx can serve as a reverse proxy or not... and I need 
to merge all this information in a single scalable system, but I can't 
find an unified source of information.


Can anyone help me on it?

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users" group.
To post to this group, send email to django-users@googlegroups.com.
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For more options, visit this group at 
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