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Appendix A. Operating systems specifics 319
/dev/sdc - 2nd DS6000 volume, seen by HBA 0
/dev/sdd - 1st DS6000 volume, seen by HBA 1
/dev/sde - 2nd DS6000 volume, seen by HBA 1
/dev/sdf - new DS6000 volume, seen by HBA 0
/dev/sdg - new DS6000 volume, seen by HBA 1
The mapping of special device files is now different than it would have been if all three
DS6000 volumes had been already present when the HBA driver was loaded. In other words:
if the system is now restarted, the device ordering will change to what is shown in
Example A-15. See also “SCSI device assignment changes” on page 316.
Example: A-15 SCSi disks after dynamic addition of another DS6000 volume and reboot
/dev/sda - internal SCSI disk
/dev/sdb - 1st DS6000 volume, seen by HBA 0
/dev/sdc - 2nd DS6000 volume, seen by HBA 0
/dev/sdd - new DS6000 volume, seen by HBA 0
/dev/sde - 1st DS6000 volume, seen by HBA 1
/dev/sdf - 2nd DS6000 volume, seen by HBA 1
/dev/sdg - new DS6000 volume, seen by HBA 1
Gaps in the LUN sequence
The Qlogic HBA driver cannot deal with gaps in the LUN sequence. When it tries to discover
the attached volumes, it probes for the different LUNs, starting at LUN 0 and continuing until it
reaches the first LUN without a device behind it.
When assigning volumes to a Linux host with QLogic FC HBAs, make sure LUNs start at 0
and are in consecutive order. Otherwise the LUNs after a gap will not be discovered by the
host. Gaps in the sequence can occur when you assign volumes to a Linux host that are
already assigned to another server.
The Emulex HBA driver behaves differently: it always scans all LUNs up to 127.
Linux on IBM iSeries
Since OS/400 V5R1, it has been possible to run Linux in an iSeries partition. On iSeries
models 270 and 8xx, the primary partition must run OS/400 V5R1 or higher and Linux is run
in a secondary partition. For later i5 systems (models i520, i550, i570 and i595), Linux can
run in any partition.
The DS6000 requires the following iSeries I/O adapters to attach directly to an iSeries or i5
Linux partition:
0612 Linux Direct Attach PCI
0626 Linux Direct Attach PCI-X
It is also possible for the Linux partition to have its storage
virtualized, whereby a partition
running OS/400 hosts the Linux partition's storage requirements. In this case, if using the
DS6000, they would be attached to the OS/400 partition using either of the following I/O
adapters:
2766 2 Gigabit Fibre Channel Disk Controller PCI
2787 2 Gigabit Fibre Channel Disk Controller PCI-X
For more information on OS/400 support for DS6000, see Appendix B, “Using the DS6000
with iSeries” on page 329.