christian.braun@xxxxxxxx wrote:
Hi list members,
I have a question regarding hardware issues for a SDI (Spatial data
infrastructure). It will consist of PostgreSQL with PostGIS and a UMN
Mapserver/pmapper set up.
At our institute we are currently establishing a small GIS working
group. The data storage for vector data should be the central PostGIS
system. Raster data will be held in file system.
Mostly the users are accessing the data base in read only mode. From
the client side there is not much write access this only will be done
by the admin of the system to load new datasets. A prototype is
currently running on an old desktop pc with ubuntu dapper - not very
powerfull, of course!
We have about 10000 € to spend for a new server including the storage.
Do you have any recommendations for us?
I have read a lot of introductions to tune up PostgreSQL systems.
Since I don't have the possibility to tune up the soft parameters like
cache, mem sizes etc., I wondered about the hardware. Most things were
about the I/O of harddisks, RAM and file system. Is the filesystem
that relevant? Because wo want to stay at Ubuntu because of the
software support, espacially for the GIS-Systems. I think we need at
least about 300-500Gb for storage and the server you get for this
price are about two dualcore 2.0 - 2.8 GHz Opterons.
Do you have any suggestions for the hardware of a spatial data base in
that pricing category?
Pay as much attention to your disk subsystem as to your CPU / memory
setup. Look at RAID-5 or RAID-10 depending on which is faster for your
setup. While RAID-10 is faster for a system seeing plenty of updates,
and a bit more resiliant to drive failure, RAID-5 can give you a lot of
storage and very good read performance, so it works well for reporting /
warehousing setups.
It might well be that a large RAID-10 with software RAID is a good
choice for what you're doing, since it gets good read performance and is
pretty cheap to implement. If you're going to be doing updates a lot,
then look at a battery backed caching controller.
Memory is a big deal. As much as you can reasonably afford to throw at
the system.
The file system can make a small to moderate impact on performance. Some
loads are favored by JFS, others by XFS, and still others by ext2 for
the data portion (only the pg_xlog needs to be on ext3 meta journaling only)
