endb 101

hello list,

i'm perfectly new to enbd and while trying to get started i think i have
not fully understand the impact of enbd & co. maybe someone can
confirm/correct my assumptions.

i tried to follow the enbd-homepage as well as the (fairly old)
linuxjournal article the homepages suggests. so, the thing i want to do is
this:

i have 2 machines, located in 2 different hosting centers and each of them
has a spare partition (hda3) for now. as i understand it each machine will
build an md0 out of hda3+nda0 (nda?). nda0 has to be "imported" [1] via
enbd-client from another machine. if that is right, then i have this:

machine A: md0 [hda3+nda0]
                       |
                       |__________________________
                                                  |
machine B: md0 [hda3+nda0], enbd-server exports hda3
(and vice versa, so enbd-server from machine-A exports hda3)

but that doesn't make sense to me, please correct me: each machine would
export the partition, which itsself is part of an md0 array! or is the
nda0 only a read-only device?

if i'm going to use 3 (or more) nodes, where would machine-C import its
nda0 from? machine-A or machine-B?
assuming machine-C imports nda0 from machine-A and A is down - the md0
from machine-C would be running in degrading mode. it *could* import it
from machine-B, but how will enbd-client notice?


i plan to use this whole thing for several applications, such as mailspool
and webspace but perhaps for the database too. i think mailspool and
webspace are "ok", but does anybody has experiences with a mysql database
storing its tables on an enbd device? is this possible?

thank you for your comments,
Christian.

[1] probably not the right term, but it just makes the most sense to me.
-- 
BOFH excuse #84:

Someone is standing on the ethernet cable, causing a kink in the cable