[OSM-dev] New database server

[Florian Lohoff]

On Mon, May 20, 2013 at 09:32:30PM -0400, Jason Remillard wrote:
> Hi,
> 
> schema). This would allow the site to scale more incrementally, and
> potentially scale to larger loads than putting all of our eggs into
> two monster servers. For the money we planning on spending on the big
> server, we could get could get several of these smaller edge servers
> with flash disks and a less expensive redundant write/history database
> server. As we need to scale, we can do it in 3,000 dollar increments
> rather 40,000 dollars increments. Having a server with 29 disks, does
> not seem like a good situation. Just a thought.

Without beeing involved in the server issues my guess is that not the
amount of API calls but the working set is the problem here.

We are talking about a multi terabyte working set. Grabbing data out of
this working set is a very tedious task. You might want to grab 10 bytes
in the front - 20 in the middle and 60 at the end. For this you need to
walk through multiple gigabytes of indexes and move your disk heads like
1750 times.

Not looking at SSDs the number of spindles is the concurrency you can
get from this. The more heads - the more concurrent accesses.

SSDs will help accelerate indexes but today are not a solution for the
full database comparing € or $.

Flo
-- 
Florian Lohoff                                                 f at zz.de
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