SCF Reference Manual for the Storage Subsystem (G06.28+, H06.05+, J06.03+)

1. Spare the sector containing the address identified in the BAD report.
-> CONTROL $DATA00-M, SPARE %H795C
The CONTROL command assigns an alternate sector for the data in the spared sector and
makes an entry into the defect log.
If either of these events occur during a spare operation, the specified sector is not spared,
and an error message is displayed:
• All spare sectors on the disk are in use.
• The added defect map is full.
• In either case, you must replace the disk.
2. Verify the defective sector has been replaced:
-> INFO $DATA00, BAD
If the defective sector was spared, it no longer appears in the detailed report.
Correcting Doubly Allocated File Extents
The REBUILDDFS attribute of the CONTROL DISK command rebuilds the disk free space table. This
process also gets rid of doubly allocated file extents.
File extent overlaps (doubly allocated file extents) are caused by a hardware or software error. A
doubly allocated file extent is an error condition that occurs when the same page is allocated more
than once to a single file, to two different files, or to a file and available free space. Report such
errors to your service provider. Use the procedures described next to resolve the problem.
Considerations for the REBUILDDFS attribute
Use this attribute if one of these events occurs:
• File-system error 58 has occurred (the disk free space table is marked bad).
• The results from a DSAP command indicate that free space has been lost over time.
• You have resolved a problem with doubly allocated file extents (by purging one of the two
conflicting files).
If DSAP reports that a file has doubly allocated file extents, and if the message “(SQL Shadow)”
appears on the same line as the file name, the file is an SQL table that has been dropped,
but the drop is not yet committed. Such a file is not available to a TACL FILES command or
FUP INFO command. The DSAP DETAIL or SQLCI FILEINFO report can also show the SQL
shadow label.
Identifying Doubly Allocated File Extents
To identify any doubly allocated file extents:
-> DSAP $DATA00, FREESPACE
Rebuilding the Disk Free Space Table
1. Stop all applications using the disk.
2. Verify the specified volume is in the STARTED state.
3. Before initiating the REBUILDDFS operation, you must resolve any disk errors, such as unspared
sectors or doubly allocated file extents:
• “Sparing a Defective Sector” (page 104)
• “Correcting Doubly Allocated File Extents” (page 106)
4. To rebuild the disk free space table:
-> CONTROL $DATA00, REBUILDDFS
106 Managing Disks