Undocumented options

As many of you filer admins know there are a lot of undocumented options on a filer. Here are some I discovered

recently.


lun.throttle.enable

Enable or disable the scsi target throttling code completely. This is the mechanism to prevent any one host system

from monopolizing all of the filer's SAN resources and thus starve out other hosts.


lun.throttle.log_interval

Number of minutes to wait between syslogs/snmp traps when a throttle has been exceeded. max is 1440 (one day)

min is 0 which disables logging/trapping completely. default is 60 (one hour).


lun.throttle.percent_hba

percentage of a SCSI target HBAs command block pool to use for throttling. Setting this to greater then 96 will

probably prevent throttling from working because the HBA will begin sending QUEUE_FULL on it's own without

notifying ONTAP. Setting this to less than 96 will probably just waste resources on the HBA.


lun.throttle.percent_qfull

percentage of command block pool to respond to with QUEUE_FULL when a throttle is exceeded.


Not all there options are usefull in every case, but at least now they are documented in some way :-)