Chapter 8: Adding a Disk
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Unix Hard Disk Basics
Installation and Configuration
Barry Kane CMSC-691X
Basic Steps
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Choose Disk
Install Hardware
Create Device Files
Partition
Format file system
Configure, Label, & Mount
Choose Disk
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SCSI
IDE (ATA)
Fibre Channel
USB
FireWire (IEEE 1394 or iLink)
SCSI
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Small Computer System Interface
5, 10, 20, 40, 80 or 160 MB/sec.
7 to 15 devices per bus
Good at arbitrating multiple bus requests
The Evolution of SCSI
Version
SCSI-1
SCSI-2
Fast SCSI-2
F/W SCSI-2
Ultra SCSI
W-U SCSI
W-U2 SCSI
Freq.
5 MHz
5 MHz
10 MHz
10 MHz
20 MHz
20 MHz
40 MHz
Width
8 bits
8 bits
8 bits
16 bits
8 bits
16 bits
16 bits
Speed
5 MB/s
5 MB/s
10 MB/s
20 MB/s
20 MB/s
40 MB/s
80 MB/s
Len
6m
6m
3m
3m
1.5
1.5
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W-U3 SCSI 80 MHz 16 bits 160 MB/s —
Diff. Len
25m
25m
25m
25m
25m
25m
25m (HVD)
12m (LVD)
12m (LVD)
IDE
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Integrated Drive Electronics
Inexpensive
competes for bus access (only one at a time)
max 2 devices/bus
Dependent on BIOS
– First 1024 cylinders for boot access
Connect the Disk
• IDE- choose master or slave, and IDE bus
number
• SCSI - make sure cables are properly
terminated. Pick device number.
Low Level Format
• Make sure device entry exists (/dev/xxxx)
• Format the disk using manufactures
programs -- most disks come preformated
Partition
• fdisk, pdisk, cdisk
• File systems and swap
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ext2
Fat32
Unix
Swap
HFS
Others....
Create File System
• Unix, Swap, or other file systems
• mkfs or newfs
• Check the file system - fsck
– Also used to repair a fs with the -r option
– Can walk through the fstab file and check
partitions in the order specified by the Pass
parameter
Label and Mount
• mount & umount
– mount -t iso9660 /dev/cdrom /mnt/cdrom
– umount /mnt/cdrom
– mount -a
Label and Mount
• /etc/fstab file
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Device file or virtual file system
Mount point
File system type
Options
Dump
Pass#
fstab file example
# Device
Mountpoint FStype Options
Dump Pass#
/dev/wd0s1b
none
swap
sw
0
0
/dev/wd0s1a
/
ufs
rw
1
1
/dev/wd0s1f
/usr
ufs
rw
2
2
/dev/acd0c
/cdrom
cd9660
ro, noauto 0
0
proc
/proc
procfs
rw
0
0
nfs
rw
0
0
server:/export /server
Adding a Disk to Red Hat Linux
• Install new disk
– IDE
• make sure bios can recognize
– SCSI
• scan SCSI bus for ID conflict
• SCSI bios can low level format
• if no interface boot to see if you must install a SCSI
driver before the kernel can recognize the disk
Adding a Disk to Red Hat — cont
• Ignore initial warnings about the partition
table — partitioning after system booted
• First check to see if device files exist
– form /dev/sdXN
– first on chain, first partition /dev/sda1
• If no device file then make them
– /dev/MAKEDEV script
• e.g., # cd /dev
# ./MAKEDEV sda
Adding a Disk to Red Hat — cont
• Ready for partitioning — fdisk
– many variations — read man page for system
• Good to make first partition small to ensure
for old BIOS and other operating systems
• Warning if greater than 1024 cylinders
– for runtime software (e.g., LILO)
– other OS boot & partition software
• e.g., DOS FDISK, OS/2 FDISK
Adding a Disk to Red Hat — cont
• fdisk program
– interactive — press m for command list
– command list
• n to create a new partition
• t to change the partition type
• p to print the partition table
• w to write the partition table to disk
Adding a Disk to Red Hat — cont
Command (m for help): new
e extended
p primary partition (1-4): p
Partition number (1-4): 2
First cylinder (256-5721, default 256): 256
Last cylinder or +size or +sizeM or +sizeK (256-1275, default 1275): 511
– nothing changed on disk until you tell fdisk to write the
partition table
• room for four “primary” partitions but can”extend” by
pointing to another table with four more
Adding a Disk to Red Hat — cont
• 2nd partition — create a swap partition
– change type to LINUX SWAP
Command (m for help): type
Partition number (1-4): 2
Hex code (type L to list codes): 82
Changed system type of partition 2 to 82 (Linux swap)
• 3rd partition — remainder of disk
Adding a Disk to Red Hat — cont
• Review
Command (m for help) print
Command (m for help) print
Disk /dev/sda: 255 heads, 63 sectors, 5721 cylinders
Units = cylinders of 16065 * 512 bytes
Device
Boot Start End Blocks
Id
/dev/sda1
1 255 2048256
83
/dev/sda2
256 511
2056320
82
/dev/sda3
512 5721 41849325
83
System
Linux
Swap
Linux
Adding a Disk to Red Hat — cont
• If satisfied write the table to disk
Command (m for help) write
Command (m for help) write
The partition table has been altered!
Calling ioctl( ) to re-read partition table.
SCSI device sda: hdwr sector=512 bytes. Sectors=91923356 [44884] [44.9GB]
sda: sda1 sda2 sda3
Syncing disks.
Adding a Disk to Red Hat —
cont
• Make a file system on your new partitions
– mk2fs /dev/sda1
– mkswap -c /dev/sda2
• Check the new file system
– fsck -f /dev/sda1
Adding a Disk to Red Hat —
cont
• Mount the partition
– mount /dev/sda1 /tmp
• Enable swap
– swapon /dev/sda2
• Check your work
df /tmp
Filesystem
/dev/hdb1
1k-blocks
2071384
Used Available Use% Mounted on
349816
1616344 18% /
• Edit the fstab file to save your work for next time