[OSM-dev] Alternative tile webserver needed?

Robert (Jamie) Munro rjmunro at arjam.net
Fri Apr 27 17:51:37 BST 2007


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Dirk-Lüder Kreie wrote:
> Nick Hill schrieb:
>>> Hello Sebastien
>>>
>>> The tiles drive is 160Gb and is currently running at 80% space usage and rising.
> 
> ReiserFS is said to slow down considerably if it gets past 85% full.
> 
>>> The problem is simply that the tile generation process is taking every available 
>>> second of disk I/O. Backing off the generator process will provide enough I/O 
>>> time for the tiles to be read and more-or-less solve the problem.

It seems unlikely that network upload bandwidth would be greater than
disk I/O bandwidth. Therefore the problem is probably not absolute disk
I/O, but how efficiently it is being used. Perhaps we should look at
tuning the ReiserFS options - disabling journalling, for example, or we
could try other filesystems. If the problem is tile uploads, the new
exponential backoff features of T at H clients should help a bit.

Another thought I had is try try serving the tiles with TUX, the kernel
web server, which is extremely fast and efficient - it never makes
multiple copies of the file (or parts of the file) in RAM, it just tells
the network card to get the data from the disc buffer directly. This may
free up apache processes and RAM and make things more responsive.
Disclaimer: I haven't ever tried to run TUX myself - I don't know how
well it works in practise.
http://en.wikipedia.org/wiki/TUX_web_server

Robert (Jamie) Munro
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