[dm-devel] Multipath and HSG80 phase 2

[christophe.varoqui at free.fr]

Have you noticed the lpfc module refcounting looks shaky ?

xa-s05:~# lsmod
Module                  Size  Used by
dm_round_robin          5248  1
af_packet              25228  2
iscsi_sfnet           124956  0
ipv6                  273376  22
smbfs                  72328  3
lpfc                  159968  946
scsi_transport_fc      10368  1 lpfc
...

regards,
cvaroqui

Selon James.Smart at Emulex.Com:

> Christoph,
>
> I can think of at least 1 reasonable reason why you have "long" delays with
> the Emulex driver. It attempts to hide temporary device loss for normal
> operation. Thus, there's a timer that waits before we start erroring i/o. For
> multipathing - you want this timer as low as zero.
>
> If you're running the 8.x driver , try setting the module parameter
> lpfc_nodev_tmo=0. Also, older driver revs had issues with "cable pulls",
> which are the port removal tests. In order to get decent behavior, we
> required a kernel patch (in 2.6.10-rc's), a minimum driver rev of 8.0.14 (but
> I'd run the latest anyway - it's 8.0.16), and compilation by "make
> BUILD_FC_TRANS=1" (see the RELEASE-NOTES file).  Sorry this isn't plug-n-play
> yet. It will be as we complete the upstream process.
>
> -- James S
>
> > -----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: Thursday, December 09, 2004 11:38 AM
> > To: device-mapper development
> > Subject: Re: [dm-devel] Multipath and HSG80 phase 2
> >
> >
> >
> > > I have already sent Christophe a patch for this.  The
> > problem was he set p,
> > > moved p, realloced dst, and expected dst to start at the same memory
> > > locating it was at before reallocing, which may or may not
> > be true.  The fix
> > > moves the p assignment and movement after the realloc call.
> > >
> > Indeed,
> > can you audit your fixes in
> > http://christophe.varoqui.free.fr/multipath-tools/multipath-to
> > ols-0.4.0.tar.bz2
> > before I release it ?
> >
> > ... and report on general behaviour.
> >
> > I'm also interested in knowing how your servers behave when
> > you disable ports
> > during IO. The device mapper seems fragile here on
> > StorageWorks HW and Emulex
> > HBA.
> >
> > Precisely, I experience a looong delay with all IO blocked,
> > then an oops, then
> > IO restart on remaining paths. But then re-enabling port
> > doesn't make the
> > device mapper happy and I have to remove-add-cycle the path
> > at the SCSI layer
> > for the DM to accept it again in maps.
> >
> > regards,
> > cvaroqui
> > --
> >
> > --
> > dm-devel mailing list
> > dm-devel at redhat.com
> > https://www.redhat.com/mailman/listinfo/dm-devel
> >
>
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