[HyperDB] setup question

[Beck, Joe]

I¹m new to hyperdb & need some help getting a dev env configured for a POC.
we have mysql in a master-slave config and would like to leverage hyperdb
for 2 things--> split reads/writes and support multiple data center.

For now, the focus is on splitting the reads & writes.
after going thru the install steps it seemed like a pretty simple process,
but I¹m getting hung up on the add_db_server line in db-settings.php
originally I had:

add_db_server('global', 0, '', 0,
0,'172.18.0.52:3306','172.18.0.52:3306','blogs_sprint','blogs_sprint','blogs
_sprint');  //wp1 as read svr
add_db_server('global', 0, '', 1,
0,'172.18.0.55:3306','172.18.0.55:3306','blogs_sprint','blogs_sprint','blogs
_sprint');  //wp2 as write svr

but was getting the following error:
Unable to connect to : while querying table 'wp_1_options' (global_w)

then I was questioning the horizontal partitioning part of this.
so I commented out the first add_db_server line but still getting the same.
then, I started going thru the code & tried changing my add_db_server line
to
add_db_server('global_w', 0, '', 1,
0,'172.18.0.55:3306','172.18.0.55:3306','blogs_sprint','blogs_sprint','blogs
_sprint');  //wp2

I stopped getting the orig error but got the std can¹t find your blog msg:
No WPMU site defined on this host. If you are the owner of this site, please
check <a href='http://codex.wordpress.org/Debugging_WPMU'>Debugging WPMU</a>
for further assistance.

Any suggestions or guidance on this is greatly appreciated.
we¹re using wpmu 2.8.6 & I downloaded the latest hyperdb, don¹t see a
version on this.

thanks,
Joe