FIBER CHANNEL ADAPTER SETTINGS

root@aix21b09: / # lsattr -El fscsi0
attach       switch       How this adapter is CONNECTED         False   <-- shows actual connection protocol (None,switch,al lehet)
dyntrk       no           Dynamic Tracking of FC Devices        True    <-- dynamically follows SAN changes
fc_err_recov delayed_fail FC Fabric Event Error RECOVERY Policy True    <-- 3. delayed_fail or fast_fail
scsi_id      0x133300     Adapter SCSI ID                       False
sw_fc_class  3            FC Class for Fabric                   True

root@aix21b09: / # lsattr -El fcs0
bus_intr_lvl  305        Bus interrupt level                                False
bus_io_addr   0xffc00    Bus I/O address                                    False
bus_mem_addr  0xfffbf000 Bus memory address                                 False
init_link     al         INIT Link flags                                    True    <--al or pt2pt
intr_priority 3          Interrupt priority                                 False
lg_term_dma   0x800000   Long term DMA                                      True    <--deafault 0x200000, max. 0x8000000
max_xfer_size 0x100000   Maximum Transfer Size                              True    <--default is 100000, max 1000000
num_cmd_elems 200        Maximum number of COMMANDS to queue to the adapter True    <--default 200, max is 1024 or 2048
pref_alpa     0x1        Preferred AL_PA                                    True
sw_fc_class   2          FC Class for Fabric                                True


attach:(sets the Fiber Channel topology)
    none: if no cable has been plugged in
    al: all devices are in a loop or ring, similar to token ring networking. The failure of one device causes a break in the ring.
    switch: all devices or loops of devices are connected to Fibre Channel switches, similar conceptually to modern Ethernet implementations  

dyntrk:
    http://publib.boulder.ibm.com/infocenter/systems/index.jsp?topic=/com.ibm.aix.prftungd/doc/prftungd/fast_fail_dynamic_interaction.htm
    If it is on yes, it enables dynamic changing of fibre channel cable connections on switch ports or storage ports.
    We have changed few StoragePorts to another Switch last saturday ==> that means, that the HardwarePath changed for these servers,
    where the Option "dyntrk" is set to no. --> reconfigure your disks

fc_err_recov:
    http://publib.boulder.ibm.com/infocenter/systems/index.jsp?topic=/com.ibm.aix.prftungd/doc/prftungd/fast_fail_dynamic_interaction.htm

    delayed_fail: waits some time before acting.
    fast_fail is useful where multipathing software is used. This would support faster failover to alternate paths

init_link:
    from online help: "Do not change this attribute unless directed by IBM support."
    al: arbitrared loop : first tries al, then pt2pt, if not succes then link remains down
    pt2pt: tries pt2pt, if not succes then link remains down

lg_term_dma:
    it controls the DMA memory resource that an adapter driver can use.
    If you have a dual port adapter the maximum value is divided between the adapter ports.

max_xfer_size:
    controls the maximum transfer size. You can increase this value to improve performance.
    Different storages might need different values to utilize the performance

num_cmd_elems:
    Maximum number of commands to be queued to the adapter.
    When a large number of supported storage devices are configured, you can increase this to improve performance.