Re: [9fans] FileServer grid

[erik quanstrom <quanstro@quanstro.net>]

> Hello every one...
> In a context of really heavy load and high availability needs, I'm
> evaluating plan 9 to implement a fileserver grid to be used by a web server
> for temporary storage (session's serializations, for example).
>
> I'd like to build a Plan 9 grid exposing a unique filesystem mounted by all
> the web servers.
>
> Each session could be accessible from any web server instantly, but what if
> a fileserver in the grid break?
> Is there a way to mantain such a session (actually the file storing the
> session data) available by keeping it sincronized beetween the Plan 9
> fileservers?

my 2¢.

before plan 9 got a shiny osi license, i did something like this
on linux.  since it was linux, the backend server took commands
much like a scsi device does rather than use 9p.  since there
were no reasonable threading option in those days, it worked
like a task-based operating system.  we used select to schedule
work.  all state was written to disk so that the death of the server
was not fatal.  horrible, i know.  but it worked reasonably well
without declaring war on the system we needed to use.  having
two web servers would have been easy in this setup.  having
multiple back-end servers was not possible.  but neither was ever
a performance limitation for us so it remained unexplored.
this is because all the work was pushed to a cluster of workers
fronted by the backend server.  they were always the limitation.

at some level of throughput, this server would be a limitation.
i would be suprised if the limitation would not be the speed of
your network.  since the amount of traffic this server sees should
be much less than the amount of web traffic, one machine with
a 10gbe card could move a lot of data.

- erik