[CentOS] CentOS 4.4 lvm and drbd 0.8?

Sun Mar 4 17:50:42 UTC 2007
Les Mikesell <lesmikesell at gmail.com>

Ross S. W. Walker wrote:
> If you were running a later kernel version of MD, it is conceivable
> that you could create a mirror with a remote storage drive over
> iscsi.
> It would be up to you though to figure out how to fail-over to it
> and to limit the bandwidth MD takes to that remote mirror and
> releasize that it will always be fully synchronous and so
> performance may not be the best over a WAN.
> You can also use a pair of vise grip plyers to do the job of an
> adjustable wrench, but it will probably strip the bolt in the
> process.

Unix has always been about combining tools that each do one job well. If 
we already have a tool (iscsi) that exports remote block devices well, 
following standards that would the actual storage to be on non-linux 
devices, and another tool (md raid) that mirrors block devices, why not 
combine them instead of inventing yet another special purpose tool?  I 
realize that drbd and nbd were developed before iscsi, but now that 
there is a standard cross-platform network block device, why shouldn't 
it be used?  MD might need some new options to make it work as 
efficiently in this scenario, but that seems like a more useful place to 
  add features - that is, there might be other situations where MD 
mirroring to an external iscsi partition would be useful, or even 
combining many iscsi exports into one raid volume.

   Les Mikesell
    lesmikesell at gmail.com