[Samba] about samba failover

[Davor Vusir]

2014-06-28 20:16 GMT+02:00 steve <steve at steve-ss.com>:
> On Sat, 2014-06-28 at 20:02 +0200, Davor Vusir wrote:
>
>>
>> Never the less, domain based DFS works. Thanks to Garming, if I recall
>> correctly.
>
> Hi
> That's exactly what we want. Two domain file servers carry the same
> share. One goes down, there's still another left with the same share.
>
> Can you point us at a howto?
> Thanks,
> Steve
>
>

Hi!

I haven't found a howto. If you can't Explore to
\\example.org\netlogon, I suggest you revert to Ubuntu 12.04 for
starters. :)

According to the documentation
(https://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/msdfs.html),
it is not possible in my opinion. At least not with automatic
failover. Because there is not enough information embedded in Sambas
implementation that informs the (Windows) client which server is to
prioritize and which is secondary and for how long this information is
valid. You can create links to several shares but you can't determine
which server the client will connect to (if it does not connect
alphabetacally(?)). If client A connects to server A the first time,
and client B connects to server B, you have to implement two-way
synchronization. There is no way to determine if the opposite occurs
at the next logon. The documentation fails to tell.

The only thing you know is that domainbased DFS is possible. The
availability solution is for you to decide.

I think it boils down to a solution with one (1) link to either a cold
stand-by server or a hot stand-by server(cluster) of some sort.

If you choose the cold stand-by solution, you'll have to 'relink' to
the stand-by server manually in case of server crash. Does rsync copy
open files? How often is enough? Every five minutes? Or is inotify
(http://www.kutukupret.com/2011/06/28/postfix-one-way-maildir-replication-backup-using-inotify-and-rsync/)
good enough?

If you choose the hot stand-by solution, I think DRBD will be satisfactory.

With the first solution you will loose data/information. The second
guaranties consistency.

The trick is one link to one server. High avaliability not included.

Regards
Davor