[dm-devel] 2.6.10-rc1-udm1: multipath work in progress

[Alasdair G Kergon]

On Tue, Nov 02, 2004 at 11:22:04PM +0100, christophe varoqui wrote:
> > [Even ignoring the suspend/resume queueing issues that aren't
> > resolved yet.]
> I would guess they need resolving anyway
 
Yes, but no guarantees it can be done efficiently yet.
(i.e. expect a performance hit whenever a table is reloaded)

> But in a low memory situation I feel your scheme won't bring much more
> garanties : it relies on userspace too after all.

After paths have genuinely failed.
 
The other point is that I'm trying to view the loaded table as a 
static long-term representation of the configuration.  It should 
normally only need changing if the admin decides to change things.
Once it has loaded the table, the roles of userspace are:

  - to deal with short-term state changes by testing paths pro-actively 
and reinstating/failing them and/or enabling/disabling PGs according 
to requested policy, 

  - to maintain statistics and report problems to the sysadmin.

Alasdair
-- 
agk at redhat.com