[dm-devel] [ANNOUNCE] multipath-tools-0.1.4
Duane Grigsby
duane.grigsby at qlogic.com
Wed Mar 17 18:39:31 UTC 2004
Does the multipath tools provide policies for during failover as well?
> -----Original Message-----
> From: dm-devel-bounces at redhat.com
> [mailto:dm-devel-bounces at redhat.com]On
> Behalf Of christophe.varoqui at free.fr
> Sent: Wednesday, March 17, 2004 9:22 AM
> To: device-mapper development; Lars Marowsky-Bree
> Cc: device-mapper development
> Subject: Re: [dm-devel] [ANNOUNCE] multipath-tools-0.1.4
>
>
> Selon Lars Marowsky-Bree <lmb at suse.de>:
> >
> > Hi, I'm kind of unsure. What does multipath-tools now mean
> for LVM2 and
> > EVMS2's multipath support, given a distributors perspective? ;-)
> >
> > Do the multipath tools handle all multipath scenarios we
> may encounter
> > (or at least are supposed to), and will LVM2 and EVMS2
> stack cleanly on
> > top of it?
> >
> the multipath-tools design is policy agnostic :
>
> the multipath configuration tool has 2 sets of policies :
>
> * paths grouping policies (drive the number and content of
> priority groups) :
>
> * one priority group (full IO spreading)
> * one priority group per path (failover, only one path
> active at a time)
> * one priority group by serial number (spread IO to all
> paths through a
> controler in a pair)
> * one group for active paths, one group for failed paths
> (for controlers that
> disable their fallback paths)
>
> * UUID fetching policies (methods to get the UUID that will
> be used to coalesce
> paths into multipaths)
>
> * SCSI INQ EVPD page 0x83 : LU WWID
>
> the multipathd daemon has only one set of policies : methods
> to determine if a
> path is up or down.
>
> * do a SCSI TUR
> * do a test IO
>
> policies can be added to fit every needs.
> policies are selected based on the SCSI strings tuple (vendor/product)
>
> hope it helps,
> cvaroqui
>
>
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