Sense byte information
251
Mainframe Features and Support
Sense byte information
Note: The information presented in this chapter is only applicable to
Symmetrix drives connected to mainframe hosts.
The Symmetrix system presents a unit check status in the status byte
to the channel whenever it detects an error condition. The error
condition can be one of the error types associated with data such as a
data check, command reject, overrun, or equipment check.
The channel issues a sense command to retrieve the sense data from
the Symmetrix system. The host places the sense data in the Error
Recording Dataset (ERDS) where the EREP subsequently uses it for
its reports.
Sense byte error data may also appear on the system operating
console. The format of the error data reported to the operator console
depends on your operating system. Sense byte data at the host is
presented in 24-byte compatibility mode or 32-byte mode for 3990
emulation.
Console error
messages
Figure 60 on page 251 is an example of a typical z/OS console error
message for 24-byte sense data.
Figure 60 Typical console error message
The unit status and channel status (CSW characters) indicate why the
operation terminated. The unit status is bits 32–39 in the CSW (370
mode) and bits 0–7 of Word 2 of the SCSW (XA and ESA mode). The
IOS0001xxx,xx,xxx-xxx,xx,xxxx,xxx-xxx,xxx-xxx,xxxxxx,xxxxxxxx
Device number
Channel path ID
Error description (12 characters)
Command code (2 characters)
CSW status (4 characters:
0-1 - Unit status, 2-3 = Channel status)
Sense data (4 to 48 characters)
Seek address (12 characters)
Volume ID (6 characters)
Job ID (8 characters)
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