On Tue, Sep 19, 2006 at 08:23:54AM -0400, Romanowski, John (OFT) wrote: > Hannes, > I'm confused that SLES 9 added a parameter, multipath=, to switch "off > multipathing in the initrd, > ie for the root fs" > > but Novell says specifically for SLES 9 that "Currently, DM MPIO is not > available for either the rooti > or the boot partition, as the boot loader does not know how to handle MPIO." > Argl. No, it's me getting confused.
The multipath parameter in SLES9 is actually an evil hack which switches of the partition detection from the block layer. It's never meant to be a properly documented boot parameter, more something of a performance tweak. Main reason here is that _reading_ from a disk (as the partition scanning code does) might trigger failover on certain arrays, which again might take some time for the failover to occur. And as the devices are scanned sequentially, you might end up failing the path back and forth several times, each time encountering the time penalty for switching paths. We had someone where this partition table scanning alone took several hours to complete. The statement about SLES9 and multipathing on root not supported still stands. Cheers, Hannes -- Dr. Hannes Reinecke [EMAIL PROTECTED] SuSE Linux Products GmbH S390 & zSeries Maxfeldstra�e 5 +49 911 74053 688 90409 N�rnberg http://www.suse.de ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
