[OSM-dev] Map rendering and SSDs

[NopMap]

Hi!

We recently added a 128GB SSD drive to a render server and maybe some of you
might find the results useful for their own hardware considerations.

The server is a quadcore, debian linux with a tirex - mapnik - PostGIS
rendering chain. Before the upgrade, tiles and database were located on a
raid0. The bottleneck of the server was I/O performance, chiefly the selects
for rendering.

After the upgrade, the database was moved to the SSD. I ran pgbench before
and after on a huge data set in zero load situations. The results showed an
improvement of database performance by a factor of 22. The overall
performance of the rendering chain (measured from tile rendering times and
osm2pgsql import time) has improved by a factor of approximately 5. So in
short: The SSD was a worthwhile addition.

Things to keep in mind when going for a SSD:
- We partitioned only 100GB on the SSD so it always has a spare area
remaining to work with
- it is imperative that ATA TRIM is supported in write-heavy scenarios. I
had an SSD without TRIM slowly die on me in my desktop machine - worked fine
later with TRIM. In this case, TRIM required recompiling the kernel to
support it

bye
              Nop

-- 
View this message in context: http://gis.638310.n2.nabble.com/Map-rendering-and-SSDs-tp5970668p5970668.html
Sent from the Developer Discussion mailing list archive at Nabble.com.