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Managing Devices

Using ioscan:

Disclaimer: Apply to a TEST environment first. Use on production systems is at DBAs own risk.

Device addresses with ioscan.

Important options:

-f: full listing

–F: compact listing

-C: lists only the specified class

-n: lists device name

-u: : using cached info from when the system was booted.

ioscan –f

à -f: full listing.

ioscan –f | lp

à To print, if you have a networked printer.

ioscan –funC disk

à To see disks only.

ioscan –funC tape

à To see tapes only.

ioscan –FnC disk

à -n : physically goes and interrogates the current status and history of all disks.

Listing Device files:

Disks, block device:

Block device file: buffering a block of data into memory and then it is sent/written to the block device disk, (default 8000 characters are buffered, then are sent to the block device).

ll /dev/dsk displays a listing as below:

brw-|r–|— 1 bin sys 31 0×005000 c0t5d0

b: is for block device.

1: it’s got one hard link.

31: is the major number: it points to a section of code in Kernel that tells the software how to talk to this disk.

0×005000: is the minor number: is the device number which is the same as the device number from ioscan –f.

lssf /dev/rdsk/c0t5d0

à Use lssf to get identification for a disk.

Disks, raw or character device:

Character device file: Accepting one character at a time. We are communicating with the device one character at the time.

ll /dev/rdsk displays a listing as below:

crw-|r–|— 1 bin sys 188 0×005000 c0t5d0

c: is for character device.

If some of the block device files or character device files are accidentally removed, then if you reboot the system, HP Unix will re-install them automatically or you could manually re-install them:

insf -eC disk :to re-install just disks.

insf -e :to re-install all devices.

rmsf :to remove any unneeded device files.

When you need to remove a given device, you will need to use rmsf to remove the device file associated with it.

Tapes:

ll /dev/rmt

àDisplays device file name as below:

c1tod0 BEST :best density possible.

BESTb :best density possible and use Berkeley style semantic.

BESTn :best density possible but do not rewind.

BESTnb :best density possible and rewind.

DDS :lowest density possible.

0m is hard linked to BEST, 0mn is linked to BESTn.

lssf /dev/rmt/om

àTo get identification for a tape.

Using ioscan to identify tapes:

ioscan –funC tape :listing system tapes.

Device file naming convention:

c0t5d0 d0: is the device number. In case you have multiple disks on a single target address such as a RAID disk; or a piece of hardware with multiple disks.

t5: is the scsi target address.

c0: is the instance number. When system is rebooted an instance# is assigned to the device in order of their response, first respond would get the 0, then 1, etc.

Physical disks:

To determine how many physical disks (not partitions) you have on your system do:

ll /dev/dsk

or ll /dev/rdsk

/dev/dsk and /dev/rdsk points to the same physical disks, but write to them either character by character (/dev/rdsk) or 8k blocks at a time (/dev/dsk).

The number of disks you see within /dev/dsk is the number of physical disks you have on your system.

Size of a disk:

diskinfo /dev/rdsk/c0t5d0

Note that his only works with raw device files (rdsk).

Listing current file systems:

bdf

à This lists all currently mounted file systems and how they are mapped into volume groups and logical groups.

For example the following is a single line extracted from bdf command:

/dev/vg00/lvol6 1105920 569478 505227 53% /var

à This line is basically saying that file system /var is mapped to logical volume lvol6 which is a part of volume group vg00. /var is sized 1GB (1105920K), 556MB (569478K) of which is being used and it has 493MB (505227K) of free space; meaning 53% used.

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