[DRBD-user] drbd and ocfs2

Pierguido pierg75 at yahoo.it
Tue Sep 4 11:49:24 CEST 2007

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

Lars Ellenberg wrote:
> The difficulties lie within the princible of a cluster file system,
> not any specific implementation of it.
> as long as we have not implemented a form of "write-quorum", which would
> block any further writes, and not complete any pending writes until
> otherwise directed (by re-establishing or reducing the write-quorum), if
> you actively modify DRBD on more than one node, you run into diverging
> data sets whenever you have any glitch in the replication communication.
I'm just trying to understand, since i'm still new to clustered things :-)
But the process of locking files is done by the cluster fs, right? Or not?
This is why (as far as i understood) primary/primary requires a cluster fs.

> ok, as long as we only support 2 nodes, "write quorum" is a bit bold.
> but still, it is the same problem.
> there are several possible workarounds right now.
>  * never ever have a network problem when both are primary.
>    ok, that won't fly.
I'll probably use two ethernet card with channel bonding, connected with
just a cable (no switch)

>  * configure an "outdate-peer-handler", and then,
>    instead of just "outdating" the peer, really "fence" it
>    (power it off/reboot) in case of communication loss.
Ok...it's also the behavior i'd like

>  * use a DRBD cluster as your SAN, then have your cluster nodes
>    on e.g.  iSCSI clients.
>    drive your cluster file system on top of that.
So...drbd --> iscsi and then every client access to it...
Unluckily now i have just 2 servers to use...so i have to implement
every service on the same machines i use as "san".

> solution:
> support us and push towards the implementation of this "write-quorum" thing.
I's sure like to do it, but i'm not a programmer...if i can do something
else to help ypu, for sure, i'll be glad to help.
Sure i can test things once i finished this thing.


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