System Administration Guide

Repairing a Defective Sector

If a disk on your system has a defective sector, you can repair it by using the instructions in the following procedures. You may become aware of defective sectors when you:

Run surface analysis on a disk.

See "The analyze Menu" for more information on the analysis functionality of the format utility.

The defective area reported while your system is running may not be accurate. Since the system does disk operations many sectors at a time, it is often hard to pinpoint exactly which sector caused a given error. Use "How to Identify a Defective Sector by Using Surface Analysis" to find the exact sector(s).

Get multiple error messages from the disk driver concerning a particular portion of the disk while your system is running.

Messages related to disk errors look like the following:

WARNING: /io-unit@f,e0200000/sbi@0,0/QLGC,isp@1,10000/sd@3,0 (sd33):
	Error for command 'read' Error Level: Retryable
	Requested Block 126, Error Block: 179
	Sense Key: Media Error
	Vendor 'SEAGATE':
	ASC = 0x11 (unrecovered read error), ASCQ = 0x0, FRU = 0x0

The above console message indicates that block 179 may be bad. Relocate the bad block by using the format utility's repair command or use the analyze command with the repair option enabled.

How to Identify a Defective Sector by Using Surface Analysis

Become superuser.

Unmount the file system in the slice that contains the defective sector.

See mount(1M) for more information.
# umount /dev/dsk/device-name

Enter the format utility by typing format.
# format

Select the affected disk.

Specify disk (enter its number):1
selecting c0t2d0:
[disk formatted]
Warning: Current Disk has mounted partitions.

Enter the analyze menu by typing analyze at the format> prompt.
format> analyze

Set up the analysis parameters by typing setup at the analyze> prompt. Use the parameters shown here:

analyze> setup
Analyze entire disk [no]? n
Enter starting block number [0, 0/0/0]: 12330
Enter ending block number [584159, 1216/9/47]: 12360
Loop continuously [no]? y
Repair defective blocks [yes]? n
Stop after first error [no]? n
Use random bit patterns [no]? n
Enter number of blocks per transfer [31, 0/0/31]: 1
Verify media after formatting [yes]? y
Enable extended messages [no]? n
Restore defect list [yes]? y
Create defect label [yes]? y

Use the read command to find the defect.

analyze> read
Ready to analyze (won't harm SunOS). This takes a long time,
but is interruptible with Control-C. Continue? y
        pass 0
   25/7/24
        pass 1
Block 12354  (18/4/18), Corrected media error (hard data ecc)
   25/7/24
^C
Total of 1 defective blocks repaired.

How to Repair a Defective Sector

Become superuser.

Enter the format utility and select the disk that contains the defective sector.

# format
Searching for disks...done
AVAILABLE DISK SELECTIONS:
    0. c0t2d0 <SUN1.05 cyl 2036 alt 2 hd 14 sec 72>
/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@2,0
    1. c0t3d0 <SUN0535 cyl 1866 alt 2 hd 7 sec 80>
/iommu@f,e0000000/sbus@f,e0001000/espdma@f,400000/esp@f,800000/sd@3,0
Specify disk (enter its number): 1
selecting c0t3d0
[disk formatted]
format>

Enter the repair command at the format> prompt.
format> repair

Enter the defective block number.
Enter absolute block number of defect: 12354 Ready to repair defect, continue? y Repairing block 12354 (18/4/18)...ok. format>
If you are unsure of the format used to identify the defective sector, see "How to Identify a Defective Sector by Using Surface Analysis" for more information.