Chapter 8: Adding a Disk

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Chapter 8 Adding a DiskUnix Hard Disk Basics

• Installation and Configuration
• Barry Kane CMSC-691X

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Basic Steps

• Choose Disk
• Install Hardware
• Create Device Files
• Partition
• Format file system
• Configure, Label, Mount

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Choose Disk

• SCSI
• IDE (ATA)
• Fibre Channel
• USB
• FireWire (IEEE 1394 or iLink)

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SCSI

• 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

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The Evolution of SCSI
Version Freq. Width Speed Len Diff. Len
SCSI-1 5 MHz 8 bits 5 MB/s 6m 25m
SCSI-2 5 MHz 8 bits 5 MB/s 6m 25m
Fast SCSI-2 10 MHz 8 bits 10 MB/s 3m 25m
F/W SCSI-2 10 MHz 16 bits 20 MB/s 3m 25m
Ultra SCSI 20 MHz 8 bits 20 MB/s 1.5 25m
W-U SCSI 20 MHz 16 bits 40 MB/s 1.5 25m
W-U2 SCSI 40 MHz 16 bits 80 MB/s 25m (HVD)
12m (LVD)
W-U3 SCSI 80 MHz 16 bits 160 MB/s 12m (LVD)
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IDE

• 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

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Connect the Disk

• IDE- choose master or slave, and IDE bus number
• SCSI - make sure cables are properly terminated.
  Pick device number.

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Low Level Format

• Make sure device entry exists (/dev/xxxx)
• Format the disk using manufactures programs --
  most disks come preformated

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Partition

• fdisk, pdisk, cdisk
• File systems and swap
• ext2
• Fat32
• Unix
• Swap
• HFS
• Others....

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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

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Label and Mount

• mount umount
• mount -t iso9660 /dev/cdrom /mnt/cdrom
• umount /mnt/cdrom
• mount -a

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Label and Mount

• /etc/fstab file
• Device file or virtual file system
• Mount point
• File system type
• Options
• Dump
• Pass

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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
server/export /server nfs rw 0 0
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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

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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

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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

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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

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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
  canextend by pointing to another table with
  four more

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Adding a Disk to Red Hat cont

• 2nd partition create a swap partition
• change type to LINUX SWAP
• 3rd partition remainder of disk

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)
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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 System /dev/sda1
1 255 2048256 83 Linux /dev/sda2 256
511 2056320 82 Swap /dev/sda3 512
5721 41849325 83 Linux
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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 sector512
bytes. Sectors91923356 44884 44.9GB sda
sda1 sda2 sda3 Syncing disks.
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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

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Adding a Disk to Red Hat cont

• Mount the partition
• mount /dev/sda1 /tmp
• Enable swap
• swapon /dev/sda2
• Check your workdf /tmpFilesystem
  1k-blocks Used Available Use Mounted
  on/dev/hdb1 2071384 349816
  1616344 18 /
• Edit the fstab file to save your work for next
  time