IBM System storage DS6000 Series, Redbooks

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DS6000 Series: Concepts and Architecture
scsi_hostadapter3 qla2300
options scsi_mod max_scsi_luns=128
Adding FC disks dynamically
The commonly used way to discover newly attached DS6000 volumes is to unload and reload
the Fibre Channel HBA driver. However, this action is disruptive to all applications that use
Fibre Channel attached disks on this particular host.
A Linux system can recognize newly attached LUNs without unloading the FC HBA driver.
The procedure slightly differs depending on the installed FC HBAs.
In case of QLogic HBAs issue the command:
echo "scsi-qlascan" > /proc/scsi/qla2300/<adapter-instance>
With Emulex HBAs, issue the command:
sh force_lpfc_scan.sh "lpfc<adapter-instance>"
This script is not part of the regular device driver package and must be downloaded
separately:
http://www.emulex.com/ts/downloads/linuxfc/rel/201g/force_lpfc_scan.sh
It requires the tool dfc to be installed under /usr/sbin/lpfc.
In both cases the command must be issued for each installed HBA, with the
<adapter-instance> being the SCSI instance number of the HBA.
After the FC HBAs rescan the fabric, you can make the new devices available to the system
with the command:
echo "scsi add-single-device s c t l" > /proc/scsi/scsi
The quadruple s c t l is the physical address of the device:
򐂰 s is the SCSI instance of the FC HBA
򐂰 c is the channel (in our case always 0)
򐂰 t
is the target address (usually 0, except if a volume is seen by a HBA more than once)
򐂰 l is the LUN
The new volumes are added after the already existing ones. The following examples illustrate
this. Example A-13 shows the original disk assignment as it existed since the last system
start.
Example: A-13 SCSi disks attached at system start time
/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 - 1st DS6000 volume, seen by HBA 1
/dev/sde - 2nd DS6000 volume, seen by HBA 1
Example A-14 shows the SCSI disk assignment after one more DS6000 volume is added.
Example: A-14 SCSi disks after dynamic addition of another DS6000 volume
/dev/sda - internal SCSI disk
/dev/sdb - 1st DS6000 volume, seen by HBA 0