Difference: FibreAttach (5 vs. 6)

Revision 62011-01-21 - ascobie

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Attaching a linux box to a SAN

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  • 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.
  • 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.
  • 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).
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  • 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.
  In the following example, LUN 4 of the NexSAN SATABlade with IP address 129.215.46.190 (81D72EBE) is mapped to /dev/mpath/36000402001ec048c6a04fcbb00000000
 
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