Re: raid framework from OpenBSD

Massimo wrote:
> I would like to know what do you think about new OpenBSD raid framework
> management.
> http://marc.theaimsgroup.com/?l=openbsd-misc&m=112630095818062
> 
> Doesn't it seems good stuff which is good for consideration?
> 
> Regards.

Creating a unified management tool for multiple RAID architectures has
been a Holy Grail for at least 10 years, if not longer.  It's
deceptively hard, though.  While it sounds straight-forward and is
relatively easy to do for 1 or 2 architectures, the vast differences in
how different architectures work makes it quickly turn into a huge mess.
This is especially true when it comes to topology discovery and
management and asynchronous event notification.  Often times the only
course is to degrade to a very simple, lowest common denominator
interface, which then starts to limit the usefulness of the tool.  I've
been involved in several professional projects in exactly this area, and
it simply is very, very hard to do well. The OpenBSD work looks
interesting, but unless they can demostrate useful operation on more
than 1 or 2 architectures, it's not terribly impressive.  That's not to
say that it can't be done and be a success, but the amount of required
effort should not be underestimated. It's relatively easy to come up
with a framework and implement one architecture module in it, then tell
everyone else to simply add more modules.

Also, it's not clear from the email whether the tool has to be manually
told to rescan and look for changes in the state of the array (not just
SES/SAFTE changes of the component drives).  Displaying status on demand
is fine, but what admin sits in front of their terminal and refreshes
their monitoring apps every 5 seconds?  The key is to have a an event
notification pipeline that can collect events in near real time, filter
them in a configurable way, and send out email/pager alerts when
appropriate.  Also, what does this mean for a datacenter full of
machines that need to be monitored?  Does a remote terminal session need
to be opened on each one in order for monitoring to work?

But, even if this particular work degrades into only being a tool for
AMI (I assume they mean MegaRAID) controllers, it's still useful and I
give them credit for doing it.

Scott