Thanks Mark. After some more thinking and research I now don't think that the "multipath=" option and the initrd code it triggers has any effect on zSeries SLES9 with the current zfcp driver and hence no effect on zSeries SLES9 dm-multipath and multipath-tools
http://download.boulder.ibm.com/ibmdl/pub/software/dw/linux390/docu/l26c ts00.pdf (How to use FC-attached SCSI devices with Linux on System z (PDF, 1.6MB)) says " Configuring the zfcp device driver- The zfcp device driver currently does not perform any port discovery or LUN scanning to determine the ports and LUNs in the SAN. Every port and LUN in the SAN that should be accessed via zfcp must be configured explicitly. Once a port and a LUN are properly configured and the adapter is set online a new SCSI device is registered at the SCSI stack." Found references saying, For Linux 2.6 kernels only, a rescan can be triggered through the /sys interface without having to unload the host adapter driver or reboot the system. The following command will scan all channels, targets, and LUNs on host H. echo "- - -" > /sys/class/scsi_host/hostH/scan "- - -" is wildcarding "b t l" Where b is the bus, t is the target, and l is the LUN to be scanned on hostH. -------------------------------------------------------- This e-mail, including any attachments, may be confidential, privileged or otherwise legally protected. It is intended only for the addressee. If you received this e-mail in error or from someone who was not authorized to send it to you, do not disseminate, copy or otherwise use this e-mail or its attachments. Please notify the sender immediately by reply e-mail and delete the e-mail from your system. -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Post, Mark K Sent: Friday, August 25, 2006 8:46 PM To: [email protected] Subject: Re: SLES9 scsi multipath initrd-linuxrc question >From what I can tell, it's doing just what the release notes say. For anything you've designated as multipathed, the script is causing a delay in checking partitions, and telling the SCSI layer to scan for all the devices on that HBA. I would presume that the multipathing stuff would happen somewhere later in the boot process. You might want to check /etc/init.d/ for something with a call to multipath (or multipathd if there is such a thing) in it. Mark Post -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Romanowski, John (OFT) Sent: Thursday, August 24, 2006 3:48 PM To: [email protected] Subject: SLES9 scsi multipath initrd-linuxrc question Zseries SLES 9 SP2 supports coding multipath=yes or multipath=all or multipath=host3,host5,...hostn in /etc/zipl.conf's kernel parameters ; Example: parameters = "multipath=yes root=/dev/..." and during linux booting up, its initrd's /linuxrc shell script checks for "multipath=" and does something (see code excerpt below) but doesn't run /sbin/multipath (part of multipath-tools package). Does anyone know what that "something" is intended for and how to use it? Does it affect /sbin/multipath at all? Or just a coincidence of name? S390x SLES9 SP2 release notes mention this " Added support for "multipath" option in initrd to support a delayed partition probing per host adapter needed in multipath setups" ----- Code from /linuxrc -----: for o in $(cat /proc/cmdline); do case $o in multipath=*) multipath_hosts=${o#multipath=} ;; esac done case $multipath_hosts in all|yes) hosts_to_scan=* ;; host*) set -- $(IFS=, ; echo $multipath_hosts) hosts_to_scan=$@ ;; esac old_pwd=$PWD if [ -d /sys/class/scsi_host ]; then cd /sys/class/scsi_host for host in $hosts_to_scan; do cd /sys/class/scsi_host/$host if [ -d device ]; then for dev in device/target*; do if [ -d "$dev" ]; then have_targets=1 fi done fi if [ -z "$have_targets" -a -w no_partition_check ]; then echo 1 > no_partition_check echo "- - -" > scan fi done cd $old_pwd fi ---------------------------------------------------------------------- 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 ---------------------------------------------------------------------- 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
