ADI - SMC tape alerts using ADI bridging (re proposal 06-420r2 and smc3r09)

Rose, Roger Rrose at
Wed Dec 19 14:20:53 PST 2007

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This is currently covered by ADC section 4.2.6 and ADC-2 Rev 8 section
>From ADC-2:
4.6 TapeAlert application client interface
The ADC device server supports a modified version of TapeAlert specified
in SSC-2. As supported by the ADC device server, the TapeAlert flags
represent states, and the state flags are not set to zero upon retrieval
of the TapeAlert Response log page (see 6.1.3). Instead, the state flags
are set to zero upon a change of the condition involved with the state
(see table 5).
-roger rose
 Product Test, Tandberg Data
From: owner-t10 at [mailto:owner-t10 at] On Behalf Of
GBarton at
Sent: Tuesday, December 18, 2007 3:07 PM
To: curtis.ballard at; michael_banther at; kdbutt at;
halvard.eriksen at; PayneR at;
Paul.Stone at; paul.suhler at
Cc: t10 at
Subject: ADI - SMC tape alerts using ADI bridging (re proposal 06-420r2
and smc3r09)
In reviewing Michael Banther's proposal for tape alert flag (06-420r2),
it occurred to me that there is a problem with SMC tape alerts in
general if ADI bridging is being used for host access to the library. 
smc3r09 clause 5.2.2 third paragraph defines deactivations for tape
alerts. Numbered list 1) states "after the TapeAlert log page is read.
The TapeAlert flags shall be deactivated on a per-initiator basis such
that active flags are available for other initiators; ".   
and in proposal 06-420r2 clause 5.4.4 last paragraph, the same statement
is made with "should" instead of "shall". 
Since a library device using ADI bridging is not aware of initiators,
the library cannot clear the flags on a per initiator basis. Does this
mean the DT device must cache the tape alert log page and keep track of
the reads of that log page? If so, how does the DT device know when to
cache a new page? And if the DT device handles the tape alert log page
on a per initiator basis, how does the library know when to clear the
flags? As far as I can tell, there is no mechanism to handle this. 
Even if proposal 06-420r2 is not incorporated into smc3, the problem
still exists. 
Geoffrey L. Barton
Overland Storage
Tiered Data Protection Made Simple

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