[dm-devel] Failover between two paths to one LU doesn't work onlinux-iscsi

[David Wysochanski]

On Thu, 2006-10-12 at 20:49 +0200, Michael Lyulko wrote:
> Dave Wysochanski wrote:
> >> I ran iozone benchmark and manually failed one of two paths. There was 
> >> no failover to second path.
> >> The iSCSI initiator retried to reconnect to the first path - 
> >> unsuccessfully. When I restored the first
> >> path - the initiator reconnected to the target via the first path.
> >>
> >> Thanks!
> >>
> >> ------------- INFO -------------
> >> Versions:
> >> device-mapper-1.01.01-1.6
> >> multipath-tools-0.4.5-0.11
> >>
> >> Machine:
> >> 2.6.5-7.244-smp; x86_64; SLES9 sp3
> >>
> >>     
> >
> > Did you set ConnFailTimeout to a non-zero value?  This sounds like it's
> > still at default (reconnect indefinately).  You also need to set the
> > Multipath variable, but it sounds like you may have done that already.
> >
> >
> >
> > --
> > dm-devel mailing list
> > dm-devel at redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >   
> Thanks! Now I set ConnFailTimeout=30 and when one of the paths failed a 
> fail-over to
> second path occurred (I had Multipath=portal). But after the first path 
> is back (iSCSI session
> is established and I can read from the device) multipath -l shows:
> <snip>
> \_ round-robin 0 [enabled]
>  \_ 0:0:6:0 sda 8:0  [failed][ready]            //   still "failed" - 
> Michael
> \_ round-robin 0 [active]
>  \_ 0:1:6:0 sdb 8:16 [active][ready]
> 
> 1. How can I configure the DM to automatically detect that a path is 
> active again?

you probably want "failback immediate"
there's also been some bugs with failback - not sure about your version
- your mileage may vary

> 2. I don't have a multipath.conf in /etc. Is 
> /usr/share/doc/packages/multipath-tools/
> the right place to take it from?

Yes, you can start with this.  I think there may be a problem with some
of the examples - make sure the "blacklist" keyword is correct - at some
point it changed from "devnode_blacklist" to "blacklist" (not sure which
one is in your version but example may be wrong).

> 3. What params in multipath.conf are a must in this case of fail-over 
> setup regarding question no.1?
> 

You might also want to look at no_path_retry and/or queue_if_no_path
options.