Fail over/Recovery roadblock

[Pavel Herrmann]

Hi,

I am currently using a single samba4 server for everything (migrated from a 
signel samba3 DC, so everything includes fileserving) in my domain, but i am a 
bit concerned about reliability, as more and more services integrate 
themselves into AD environment.

my plan is to set up two samba4 DCs and two samba3 fileservers as virtual 
machines on two separate hosts, with the aim that hardware failure of one of 
the hosts would not affect the availability (it would certainly affect 
performance, but everything should still work).

the samba4 DCs should be synchronized by DRS (hopefully DNS partition 
replication will get fixed soon, or is fixed already), GPOs would be 
synchronized by lsyncd

the problem is with fileserving, as I dont have a SAN (thay cost way too much 
for this setup), i would use drbd (with clvm and GFS2) to synchronize the 
fileservers, and CTDB to keep samba state in sync. with this i would like to 
use MSDFS to automagically balance load between the nodes (and transparently 
switch to single-node in case of a failure)


this is somewhat more complex setup than the one of the original poster, but 
the question remains the same - is this doable? are there any fundamental 
errors in my plan? what performance gain (or even loss) can i expect from 
this? anyone running a similar setup? any other ideas?

thanks
Pavel Herrmann


On Friday 10 of February 2012 12:51:14 Aaron E. wrote:
> First and primary questions are for a PDC and BDC setup .. .. The latter
> portion was high availability clustering and was more theory but I am
> interested in that also as I havn't completely made the final decision
> on strategy yet.
> 
> If I can get the proper information I will be glad to put this in wiki
> form at samba wiki. I would like to contribute somehow if not in code
> then other ways....
> 
> On 02/10/2012 11:43 AM, Scott Lovenberg wrote:
> > On 2/10/2012 9:30 AM, Aaron E. wrote:
> >> We are upgrading to S4 I'm just waiting on the servers being ordered
> >> today and there are few items on the list prior to production which
> >> includes failover/recover. In my mind unless I have a proper procedure
> >> I cannot go live so I'm looking at recovery procedures in case of DC1
> >> failure in a two DC set-up. Was hoping for some insight / procedures
> >> that people are using in a production environment. I'll list my
> >> thought process and hope others can chime in on anything I'm missing
> >> or haven't thought of.
> > 
> > To be clear, you're talking about having a PDC and a BDC, correct? Or
> > are you talking about high availability at a lower level of the stack
> > (OS, hypervisor, etc.)?