Disk Information

An additional precautionary step to help you recover from loss of critical data: before a disaster strikes is to find out how each disk on your network is partitioned and formatted and print and save this information. If a disk is damaged or destroyed during a disaster, use the disk information to recreate the disk exactly as it was prior to the disk crash. Do the same for each system Backup backs up, unless the systems are consistent in disk and filesystem layout.

When you recreate your disk configuration, you need to have partitions large enough to hold all the recovered data. Make the partitions at least as large as they were before to the crash.

Use the df command to find out how the Backup server disks are partitioned and mounted. Use the appropriate operating system command to print disk partitioning information. Do the same for any Backup clients that have local hard disks.

For example, the df -k information looks similar to this:

Filesystem            kbytes    used   avail capacity  Mounted on
/dev/dsk/c0t3d0s0     865678  624020  155098    80%    /
/dev/dsk/c0t1d0s6     265807  198729   40498    83%    /usr
/dev/dsk/c0t1d0s4      96103   57468   29025    66%    /var
swap                  107756       8  107748     0%    /tmp

The following dkinfo command examples give you information about how each disk is partitioned for a SunOS system:

% dkinfo sd0a
	SCSI CCS controller at addr f8800000, unit # 24
	1151 cylinders 9 heads 80 sectors/track
	33120 sectors (46 cyls)
	starting cylinder 0
% dkinfo sd0b
	1151 cylinders 9 heads 80 sectors/track
	197280 sectors (274 cyls)
	starting cylinder 46

The prtvtoc command example in Example 1-2 provides you information about how each disk is partitioned for a Solaris system. The device name is the "raw" device corresponding to the device name used for the output from the df command.

Example 1-2 prtvtoc Command Output

* /dev/dsk/c0t1d0s3 partition map
*
* Dimensions:
*     512 bytes/sector
*      80 sectors/track
*      17 tracks/cylinder
*    1360 sectors/cylinder
*    3500 cylinders
*    1965 accessible cylinders
*
* Flags:
*   1: unmountable
*  10: read-only
*
*                          First     Sector    Last
* Partition  Tag  Flags    Sector     Count    Sector  Mount Directory
       2      5    00          0   2672400   2672399
       3      6    00          0   1434800   1434799   /export
       4      7    00    1434800    205360   1640159   /var
       5      6    00    1640160    463760   2103919   /opt
       6      4    00    2103920    568480   2672399   /usr

If a disk is damaged, you can restore it and recover the filesystems to their original state, using the hardcopy information from these disk information commands.