Hitachi Ultrastar 15K450 (FC-AL) Hard Disk Drive Specification
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17.5 FC-AL timers
Table 87:FCAL timer values
The drive uses FCAL timers as specified in PLDA 2.1 as required in the standard.
•AL_TIME
AL_TIME represents two times the worst case round trip latency for a very large loop.
•LIS_HOLD_TIME
LIS_HOLD_TIME is the maximum amount of time between when a node receives a Loop Initialization Sequence
until it forwards it to the next node.
• R_T_TOV
R_T_TOV is used by the receiver logic to detect a Link Failure. A Link Failure is defined as loss of synchronization
for a period greater than R_T_TOV.
• E_D_TOV
E_D_TOV is the minimum time a port shall wait for the next expected frame in a sequence before detecting an error.
• R_A_TOV
R_A_TOV is defined by the PLDA to be two distinct timers.
• R_A_TOVSEQ_QUAL defines the minimum time a port shall wait before reuse of the sequence qualifiers SEQ_CNT
and SEQ_ID. The PLDA defines the value of R_A_TOVSEQ_QUAL to be zero seconds.
Twice the value of R_A_TOVELS defines the minimum time a port shall wait for the response to an Extended Link
Service Request. The PLDA defines this value to be two seconds. Therefore a port must wait twice this value (four
seconds) before timing out an ELS.
Note: In the FLA, there is no split definition of the R_A_TOV value. One timer value is used for both
R_A_TOVSEQ_QUAL and R_A_TOVELS.
• RR_TOV
RR_TOV is the minimum time a target shall wait for an Initiator to perform exchange authentication following LIP. If
this timer expires, the Target will implicitly log out the Initiator and free up the resources associated with that timer.
An RR_TOV timer is maintained for each Initiator that has logged in.
Timer Description Value
(PLDA/FLA)*
AL_TIME Arbitrated Loop Timeout Value 15 ms
LIS_HOLD_TIME Loop Initialization Sequence Hold Time 1 ms
R_T_TOV Receiver Transmitter Timeout Value 100 ms
E_D_TOV Error Detect Timeout Value 2 sec./2 sec.*
R_A_TOV Resource Allocation Timeout Value 2 sec./10 sec.*
RR_TOV Resource Recovery Timeout Value 2 sec.
LP_TOV Loop Timeout Value 2 sec.