Enhancement Proposal for SSC r12

Gold, Stephen StephenG at hpcpbla.bri.hp.com
Tue Mar 17 07:52:11 PST 1998


* From the T10 (formerly SCSI) Reflector (t10 at symbios.com), posted by:
* "Gold, Stephen" <StephenG at hpcpbla.bri.hp.com>
*
Hi all,

This note relates to the SCSI SSC command set, with a proposal for an
enhancement in the area of streaming device management/diagnostics.

Tape storage systems have a vital role to play in backing up essential
data safely and securely. Yet until recently, there had been no reliable
standard way to identify errors and potential problems that may
compromise their effectiveness or reliability. The problem was that
access to low-level diagnostic information was via vendor-unique and
technology-unique commands, and even if the information could be
extracted it could not be reliably interpreted by the software.

So about 2 years ago, Hewlett-Packard developed a new interface for tape
drive diagnostics and management called TapeAlert, utilising a currently
unused Log Sense page code 0x2E. This new interface was subsequently
made available to all other tape device vendors, and an industry Working
Group was formed to own the specification and future enhancements. The
TapeAlert interface is now endorsed and shipping by the vast majority of
tape vendors, including Hewlett-Packard, Seagate, Quantum, Tecmar,
Tandberg, Breece Hill, StorageTek, ATL, and many others. Software
support for this interface is also available across many software
vendors, such as Computer Associates, Seagate Software, Stac,
Hewlett-Packard, and more to follow.

The main aim of TapeAlert was to provide a standard high-level interface
where the device could indicate standard error conditions in the device
hardware and media to the application software using the device. The
application software actions would also be defined so that standard easy
to understand error messages would be displayed for each error
condition. Such a diagnostic system benefits both consumers/users and
manufacturers. For consumers/users, there is now a standard method to
monitor and maintain tape devices with standard easy to understand error
messages, regardless of which tape drive or application software they
are using. For manufacturers, there should be a reduction in support
calls since the users are now being immediately informed what to do in
event of problems, and advanced diagnostics can be provided by the
application software without needing device-specific knowledge.

Also, after discussion in the industry Working Group, the TapeAlert
interface was extended in the v2 specification to include other device
types, using the same basic principles of high-level diagnostic alerts
generated by the device. The extension added support for Media Changer
devices (ie tape or optical libraries), but was still fully backwards
compatible with the original TapeAlert v1 specification for tape
devices. The TapeAlert interface could also be applied to other
removable media device in the future, such as MO optical devices, or CD
optical devices.

More details on the TapeAlert interface can be found at
	http://www.hp.com/go/tapealert
There is also a private area for the TapeAlert Working Group contain
meeting minutes etc, which can be found in the Working Group section of
the main TapeAlert Web site. The access to this private area is:
	username:	TapeAlert
	password:	excal1ber
The latest version of the TapeAlert specification can be found as HTML
in the private Working Group area, or downloaded as a Word97 file:
	http://www.hp.com/tape/tapealert/download/taspec20.exe

The intention is to file a public comment to include the TapeAlert Log
Sense page 0x2E in the SCSI-3 Sequential device commands (SSC) when the
SSC r12 draft is released for review (project 0997-D).
The SCSI-3 draft standard for Primary Commands, (SPC) already shows Log
Page code 2E as reserved for potential use by specific device types. The
TapeAlert interface also uses the SCSI Mode page 0x1C, but has been
defined to be compatible with the currently defined SCSI-3 draft
definition for this page.

Any comments or suggestions would be very welcome, particularly any
ideas on how to word the public comment (this is the first time I have
done one).

Regards,
	Stephen Gold
	Hewlett-Packard
	TapeAlert Working Group Chairman

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