9840/9940/T10000 - What are the Correct MIH Values per Drive Type and Emulation Settings in a Native and RTD Environment

Asset ID:	1-71-1014180.1
Update Date:	2017-05-19
Keywords:

Solution Type Technical Instruction Sure

Solution 1014180.1 : 9840/9940/T10000 - What are the Correct MIH Values per Drive Type and Emulation Settings in a Native and RTD Environment

Applies to:

Sun StorageTek 9840B Tape Drive - Version Not Applicable and later
Sun StorageTek 9840C Tape Drive - Version Not Applicable and later
Sun StorageTek 9840D Tape Drive - Version Not Applicable and later
Sun StorageTek 9940A Tape Drive - Version Not Applicable and later
Sun StorageTek 9940B Tape Drive - Version Not Applicable and later
All Platforms

Goal

Determine the correct MIH settings for Native and RTD 9X40 drives per device type and emulation settings.
What is the recommended MIH value for a 9840 drive
What is the recommended MIH value for a 9940 drive
What is the recommended MIH value for a T10000 drive

Solution

Select one of the following procedures:

If using 3490 Emulation Operation

9840A/B/C devices will send back a MIH value of 50 minutes as the MIH value to be used for all commands if device is operating in 3490 mode.

9940A/B devices will send back a MIH value of 167 minutes as the MIH value to be used for all commands when operating in 3490 mode.

T10K device will send back a MIH value of 197 minutes as the MIH value to be used for all commands when operating in 3490 mode as an RTD device behind a VSM. Note that this T10K device configuration can not be directly attached to an MVS host.

Note: 1.35.x09 code had a problem where the MIH value returned from the drive (in 3490 emulation) was zero instead of 50. This caused the operating system to default to a 3 minute timer. This problem was fixed in 1.35.x12 code.

If using 3590 or 3592 Emulation Operation

All MVS attached tape devices use 16 minutes and 40 seconds as the primary MIH value for read or write operations when operating in 3590/3592 mode (latest released code).

There is also a secondary MIH value that is returned depending on device type and how the device is setup in the GEN. 50m for 9840 or 167m for 9940 or 197m for T10K. The primary MIH value is used for load or R/W commands. The secondary MIH value is used for locate, file or block spacing, or DSE commands.

RTD MIH Setting

All supported tape drives , both ESCON and FICON, run according to the 3490 Operation.

Internal Comments
Note: The Missing Interrupt Handler (MIH) is a value that is used at the host to time various IO operations driven to the devices. This value can either be set by the customer by using IOS statements in PARMLIB or it can be set by each drive via read configuration data command response. SUN/STK always recommends using the later method of letting the drive determine the correct MIH value. This is especially true of drives running 3590 or 3592 emulation as these drive types can control both Primar

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