Difference: FibreAttach (6 vs. 7)

Revision 72013-05-31 - ascobie

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Attaching a linux box to a SAN

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  1. Check the profile is compiled and received by machine.
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  1. Reboot the machine. This reboot will compile the qlogic driver module for the current kernel. It will then trigger an additional reboot (Step not required for SL5)
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  1. Reboot the machine. This reboot will install the qlogic firmware RPMs and rebuild the initramfs image. It will then trigger an additional reboot.
 
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If you have just added a new volume to an array, you will probably need to get the HBA to rescan the bus to detect it. For QLogic cards, the following should work

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echo "- - -" > /sys/class/scsi_host/host_id_/scan
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echo "- - -" > /sys/class/scsi_host/host{id}/scan
  Though you will have to use the path appropriate to your HBA and port in use. For multipath you will need to do this for each port.
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Multipath

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  • The <lcfg/options/multipath.h> header enables multipath support. Note that no multipath configuration is yet possible; a component may be written in the future if it proves necessary. (Remember to use <dice/options/multipath.h> under DICE)
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  • The <lcfg/options/multipath.h> header enables multipath support. The lcfg-multipath component can be used to configure multipath behaviour : the default configuration should suffice for the majority of situations. (Remember to use <dice/options/multipath.h> under DICE)
 
  • If you are using a qlogic HBA and the qlogic supplied driver, you must disable the driver's failover option (The default is to use the stock kernel driver)
  • The storage array must export the LUNs you want to access on all fibre paths. To avoid confusion, it's a very good idea to have the LUNs map to the same volumes on each path; otherwise it is very tricky to identify which volume is which.
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  • The multipath system presents the storage volumes and partitions under /dev/mpath rather than under /dev/disk/by-id, and without a scsi prefix. The volumes are still presented under /dev/disk/by-id, but you should not use these devices as they are hard-wired to one fibre path and will not failover if that path fails.
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  • The multipath system presents the storage volumes and partitions under /dev/mapper rather than under /dev/disk/by-id, and without a scsi prefix. The volumes are still presented under /dev/disk/by-id, but you should not use these devices as they are hard-wired to one fibre path and will not failover if that path fails.
 
  • Use the /sbin/multipath -l command to list the available volumes, instead of /sbin/lsscsi and /sbin/scsi_id used in the above instructions. Where there are many storage arrays connected, it will still be necessary to use /sbin/scli to identify the array required (as documented above).
  • When adding a new volume, see above for how to probe for new volume devices. Once /sbin/lsscsi has spotted the new volume(s), check with /sbin/multipath -ll that the multipath daemon has spotted the new volume(s). Partition the volume using fdisk, as usual. If the volume appears in /dev/mpath but the partitions don't, use kpartx -a -p p /dev/mpath/vol-id to create the partition entries and new /dev/dm-{n} devices.
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-- AlastairScobie - 27 Jul 2007

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-- Updated 2013-05-31
 
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