Hi Randy, Bruce,
That is a nice piece of advise Randy. I am sorry to intrude the
conversation but I would like to ask how that "heavy raster"
manipulation would be treated by PostgreSQL/PostGIS, managed or unmanaged?
Best regards,
Ivan
Randy George wrote:
Hi Bruce,
On the “scale relatively quickly” front, you should look
at Amazon’s EC2/S3 services. I’ve recently worked with it and find it an
attractive platform for scaling http://www.cadmaps.com/gisblog
The stack I like is Ubuntu+Java+ Postgresql/PostGIS + Apache2 mod_jk
Tomcat + Geoserver + custom SVG or XAML clients run out of Tomcat
If you use the larger instances the cost is higher but
it sounds like you plan on some heavy raster services (WMS,WCS) and lots
of memory will help.
Small EC2 instance provides $0.10/hr:
1.7 GB of memory, 1 EC2 Compute Unit (1 virtual core with 1 EC2 Compute
Unit), 160 GB of instance storage, 32-bit platform
Large EC2 instances provide $0.40/hr:
7.5 GB of memory, 4 EC2 Compute Units (2 virtual cores with 2 EC2
Compute Units each), 850 GB of instance storage, 64-bit platform
Extra large EC2 instances $0.80/hr:
15 GB of memory, 8 EC2 Compute Units (4 virtual cores with 2 EC2 Compute
Units each), 1690 GB of instance storage, 64-bit platform
Note: that the instances do not need to be permanent. Some people
(WeoGeo) have been using a couple of failover small instances and then
starting new large instances for specific requirements. The idea is to
start and stop instances as required rather than having ongoing
infrastructure costs. It only takes a minute or so to start an ec2
instance. If you are running a corporate service there may be parts of
the day with very little use so you just schedule your heavy duty
instances for peak times. If you can connect your raster to S3 buckets
rather than instance storage you have built in replicated backup.
I know that Java JAI can easily eat up memory and is core to Geoserver
WMS/WCS so you probably want to look at large memory footprint for any
platform with lots of raster service. I’m partial to Geoserver because
of its Java foundation. I think I would try to keep the Apache2 mod_jk
Tomcat Geoserver on a separate server instance from PostGIS. This might
avoid problems for instance startup since your database would need to be
loaded separately. The instance ami resides in a 10G partition the
balance of data will probably reside on a /mnt partition separate from
ec2-run-instances. You may be able to avoid datadir problems by adding
something like Elastra to the mix. Elastra beta is a wrapper for
PostgreSql that puts the datadir on S3 rather than local to an instance.
I suppose they still keep indices(GIST et al) on the local instance.
(I still think it an interesting exercise to see what could be done
connecting PostGIS to AWS SimpleDB services.)
So thinking out loud here is a possible architecture–
Basic permanent setup
put raster in S3 – this may require some customization of Geoserver,
build a datadir in a PostGIS and backup to S3
create a private ami for Postgresql/PostGIS
create a private ami for the load balancer instance
create a private ami with your service stack for both a small and large
instance for flexibility,
Startup services
start a balancer instance
point your DNS CNAME to this balancer instance
start a PostGis instance (you could have more than one if necessary but
it would be easier to just scale to a larger instance type if the load
demands it)
have a scripted download from an S3 BU to your PostGIS datadir (I’m
assuming a relatively static data resource)
Variable services
start service stack instance and connect to PostGIS
update balancer to see new instance – this could be tricky
repeat previous two steps as needed
at night scale back – cron scaling for a known cycle or use a controller
like weoceo to detect and respond to load fluctuation
By the way the public AWS ami with the best resources that I have found
is Ubuntu 7.10 Gutsy. The debian dependency tools are much easier to use
and the resources are plentiful.
I’ve been toying with using an AWS stack adapted for serving some larger
Postgis vector sets such as fully connected census demographic data and
block polygons here in US. The idea would be to populate the data
directly from the census SF* and TIGER with a background Java bot. There
are some potentially novel 3D viewing approaches possible with xaml.
Anyway lots of fun to have access to virtual systems like this.
As you can see I’m excited anyway.
randy
*From:* [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] *On Behalf Of
[EMAIL PROTECTED]
*Sent:* Monday, February 18, 2008 6:35 PM
*To:* OSGeo Discussions
*Subject:* [OSGeo-Discuss] OS Spatial environment 'sizing'
IMO:
Hello everyone,
I'm trying to get a feel for server 'sizing' for a **hypothetical**
Corporate environment to support OS Spatial apps.
Assume that:
- this is a dedicated environment to allow the use of OS Spatial
applications to serve Corporate OGC Services.
- the applications of interest are GeoServer, Deegree, GeoNetwork,
MapServer, MapGuide and Postgres/PostGIS.
- the environment may need to scale relatively quickly.
- it will be required to serve in the vicinty of 5 to 10 TB of data
initially (WMS, WFS, WCS).
Can anyone shed some light on the following questions please?
- I'm assuming a Linux installation (SLES, Redhat or Debian) or possibly
Intel Solaris. Has anyone experienced any issues in these (or other)
environments that they'd like to share?
- Are there any recommendations as to dedicated network bandwidth that
should be allocated?
- Has anyone done any work with load balancing and would like to share
their experiences?
- Of the above OS Spatial products, which ones could co-exist on the
same server (excluding Postgres/PostGIS)?
Any thoughts are appreciated.
Bruce Bannerman
Australia
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