Chap02 Managing Local Disk Devices

7/30/2019 Chap02 Managing Local Disk Devices

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1AITA\SWBU\SOLARIS\08

Managing Local Disk Devices


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Basic Architecture of a Disk

Physical Disk Structure

Disk Platters

Sector

Track

Cylinder

Disk Slices (Disks are logically divided into individualpartitions known as disk slices)


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Disk slices and the different file systems they could hold

0 / (The root directorys system files)

1 swap (Swap area)

2 (Entire disk)

5 /opt (Optional Software)

6 /usr (System executables and programs)

7 /export/home (User files and directories)


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Disk Slice Naming Convention An 8 character string typically represents the full name of a slice

(c#t#d#s#)

Controller number (c#) Identifies the host bus adapter (HBA), which controls

communications between the system and disk unit

Target number (t#) Corresponding to a unique hardware address that is

assigned to each disk, tape or CD-ROM


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Disk number (d#)

Also known as the logical unit number (LUN). This numberreflects the number of disks at the target number

Slice number (s#)

A slice number ranging from 0 to 7


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Device Naming Conventions

Logical Device Names

Physical Device Names Instance Names


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Logical Device Names

Logical disk device names are symbolic links to the physical

device names kept in the /devices directory.

All logical device names are kept in the /dev directory

Example: c0t0d0s0


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Physical Device Names

Physical device names uniquely identify the physical location ofthe hardware devices on the system and are maintained in the

directory A physical device name contains the hardware information,

represented as a series of node names, separated by slashes,that indicate the path to the device.

Example: /pci@1f,0/pci@1,1/ide@3/dad@0,0:a


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Instance Names Instance names are abbreviated names assigned by the kernel

for each device on the system.

An instance name is a shortened name for the physical devicename.

Example

sdn - where sd is the disk name and n is the number, such

as sd0 for the first SCSI disk device dadn - where dad is the diskname and n is the number,

such as dad0 for the first IDE disk device


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Listing a Systems Devices

/etc/path_to_inst File

For each device, the system records its physical name andinstance name in this file.

This file is maintained by the kernel and is not advisable for

the system administrator to change this file


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Using the prtconf command To display the systems configuration information, including

the total amount of memory installed and the configuration of

system peripherals, which is formatted as a device tree.

Lists all possible instances of devices


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Using the format command To display both logical and physical device names for all

currently available disks.

To view the logical and physical devices for currently

available disks.


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Reconfiguring Devices


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Performing a Reconfiguration Boot

1. Create the /reconfigure file using #touch /reconfigure

2. Shutdown the system using #init 5

3. Turn off the power to all external devices

4. Install the peripheral device

5. Turn on the power to all external devices

6. Turn on the power to the system

7. Verify that the peripheral device has been added by issuing

either prtconf or format command


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Using the devfsadm command

Syntax: #devfsadm -c device_class

#devfsadm -i driver_name


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Usage #devfsadm -c disk

#devfsadm -c disk -c tape -c audio

#devfsadm -i dad #devfsadm -i sd

#devfsadm -i st


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To print the changes made by the devfsadm command to the

/dev and /devices directories

#devfsadm -v

To invoke cleanup routines that remove unreferenced symbolic

links for devices

#devfsadm -C


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Partitioning the Hard Disk


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Fundamentals of Disk Partitioning

1. Identify the correct disk2. Plan the layout of the disk

3. Use of the format utility to divide the disk into slices

4. Label the disk with new slice information


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format utility

Only the root user can use the format utility. If a regular

users run the format utility error message appears.


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Disk Partition Tables

As a root user, when you use the format utility and select adisk to partition, a copy of the disks partition table is read fromthe label on the disk into memory and is displayed as the currentdisk partition table.

The format utility also works with a file called /etc/format.datwhich is read when the format utility is invoked.

The /etc/format.dat file is a table of available disk types and aset of predefined partition tables that you can use to partition a

disk quickly.


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Disk Labels

The disks label is the area set aside for storing information about

the disks controller, geometry, and slices.

Another term used to describe a disk label is the volume table of

contents (VTOC). To label a disk means to write slice information onto the disk. If

failed to label the disk after defining slices, the slice information

is lost.


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An important part of the disk label is the partition table, whichidentifies a disks slices, the slice boundaries in cylinders, andthe total size of the slices.


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DEMO

Partitioning a Disk

Saving a Partition Table to the /etc/format.dat file

Using the Customized Partition Table

Viewing the Disk VTOC

Reading a Disks VTOC using the prtvtoc command

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Chap02 Managing Local Disk Devices