Reads Exhausted represents the number of reads exhausted due to
full read buffers during the most recent sampling interval.
A read processing deferral occurs when the queued direct I/O (QDIO)
program-controlled interrupt (PCI) Exit must defer processing of read
completions because a control block cannot be obtained to represent
the inbound data. Read processing deferrals for the primary and all
ancillary read queues are consolidated into the primary read queue
count.
Each OSA-Express QDIO and HiperSockets interface requires
fixed storage for read processing (which is allocated by VTAM). This
storage is acquired from CSM 4K ECSA. If you define a large number
of these interfaces (for example, by configuring multiple VLANs to
one or more OSA-Express features), then you need to consider how much
fixed Communications Storage Manager (CSM) 4K Extended Common System
Area (ECSA) storage your configuration requires. For information about
considerations for the IVTPRM00 parmlib member, see IBM
z/OS Communications Server: SNA Resource Definition Reference.
If you believe you have sufficient limits on CSM 4K ECSA, the OSA or
HiperSockets device may be overrunning the interrupt exit. In this
case an internal modification to VTAM may be warranted.
This is a critical situation.
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