How to Repair an Invalid MIR

Asset ID:	1-71-1013706.1
Update Date:	2017-09-26
Keywords:

Solution Type Technical Instruction Sure

Solution 1013706.1 : How to Repair an Invalid MIR

Applies to:

Sun StorageTek 9840A Tape Drive - Version Not Applicable and later
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 SL8500 Modular Library System
All Platforms
Checked for relevance on 19-Dec-2011.

Goal

How to repair an invalid MIR?
How to clear Invalid MIR status on an MVC?

Solution

The Media Information Region (MIR) on a tape will be gradually re-validated as the tape is used. To completely validate the MIR, the tape must be read to EOD. Any method that causes the drive to position to EOD can be used, independent of whether the tape is a host volume or a MVC. Please note that this must be EOD on the tape, not just the last active data on the cartridge.

An invalid MIR can be validated in several ways:

1. The simplest and quickest method is to write to the tape beginning with block id 0 (such as with a scratch mount). The MIR will be valid
    when the tape is unloaded. If there is live data on the tape, this method should not be used.

2. Reading to the end of existing user data will create a valid MIR. Note, this will be done at normal read
    speeds and can take an hour or more for a full tape, depending on the media capacity. Reading to the end of the data can be done from the
host using an MVS Utility or the drive offline rebuild MIR function.

Refer to <Document 1016882.1> "How to build a MIR with an offline drive" for details regarding the drive option.

3. Appending to the tape will create a valid MIR, although a slow speed read must first be done to the end
    of the existing user data.

4. If the volume is an MVC (for VSM), the VTCS utility/command INVENTRY MVC will revalidate the MIR. For VTCS 7.0 and higher, it is recommended to use INVENTRY as opposed to AUDIT. If running 6.2 or lower, the AUDIT MVC utility is used instead.

5. If the previous actions are not taken, the MIR will be gradually rebuilt over time as the tape is used. Initial performance will be low, but after multiple tape mounts (the number of mounts needed depends on how far the tape is read), performance will be back to normal.

The MVCMAINT Utility can also be used to reset the Invalid MIR status. This is only for use when the MIR has been rebuilt by other means, such as the drive's offline MIR rebuild function. Utility syntax is: MVCMAINT MVC(volser) INVLDMIR(OFF)

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