Lecture #2 Storage Devices and File Systems

Agenda

• Exercise: Using the virtual machine we created last week, install a minimal version of Red Hat 9.0 using the ISO in your depot directory.
  1. For Installation Type, choose Custom
  2. For name of machine, choose stationXX-1
  3. For Package installation, choose Minimal Install
  4. For Emergency floppy, choose Yes
• Survey of the top-level directories of a GNU/Linux virtual system
• Exercise: Create a minimal directory hierarchy for Linux under root's home directory.
  • Name the root directory slash.
  • Populate the major directories with a representative file as specified by the instructor.
• Use the dd command and device files to manipulate data on storage devices.
• Disk storage and file system handout
• Exercise: Pendrive as a second disk
  1. Use fdisk to create 1 primary, 1 extended and 2 logical disk partitions.
  2. Create an ext3 file system on the primary partition, a vfat file ssytem on the first logical partition, and swap space on the second logical partition.
  3. Mount the two filesystems and copy a file to each of them.

Slides and Questions

1. PowerPoint Slides
2. In what ways are storage systems all alike? How are they different?
3. In what way are UNIX files all alike? In what ways are they different?
4. What is the main difference between ext2 and ext3 file systems?
5. What is a superblock? an inode table? what determines the size of the logical data blocks?
6. Is there a difference between a storage device that has been formated with a single file system and one that has a single partition which is formatted with a single file system?
7. Where do file systems reside?
8. What is a mount point?
9. What is a mounted file system?
10. Why would an attempt to unmount a file system fail?
11. What is the /etc/fstab file used for?
12. Describe the difference between the mkfs command and the fdformat command.
13. Explain the relationship between file systems and the file directory hierarchy.

Assignment

1. Read the following sections from Chapter 2:
   2.1, 2.2, 2.3, 2.4, 2.6
   In sections 2.3 and 2.4 pay closer attention to GRUB rather than LILO.
   It's nice to see the similarities, but we are going to use and study GRUB since it is more versatile than LILO.

Files and File Systems

1. Overview of Storage Devices
   • IDE vs. SCSI
     1. IDE: Primary master (/dev/hda), Primary slave (/dev/hdb), Secondary master (/dev/hca), Secondary slave (/dev/hdd),
     2. SCSI: each SCSI disk has a target id (1-7) or (1-14). (/dev/sda, /dev/sdb, ...)
   • CHS
     • Cylinders: (some older BIOSs have a limitation with greater then 1024 cylinders)
     • Heads (Tracks): modern disks are not made of platters, so tracks is replacing heads.
     • Sectors: 512 bytes per sector.
   • Exercise: compute the capacity of a disk with CHS reading of: 2434/255/65
2. Disk Partitions
   • Master Boot Record
     1. Boot Loader: up to 446 bytes of machine code that reads the following partition table.
     2. Partition Table: 64 bytes that hold the type, size and location of the four primary partitions.
     3. Two-byte Signature: 0x55aa
   • Partitions
     1. Primary - up to 4
     2. Extended - maximum of 1
            May contain arbitrary number of logical partitions.
   • Exercise: Use the rest of your disk to create an Extended partition, and within that partition, create a 32MB Linux partition.
3. File systems: Raw vs. Structured data
   1. Superblock
   2. Inode Table (List)
   3. Data blocks
   4. lost+found directory
   5. File Systems are create with: mkfs -t type Device [size]
   6. Exercise: Create a filesystem in the partition you created above (/dev/hda5).
   7. Mounting and Unmounting File Systems
      • mount [device-file] [directory]
      • umount [device-file | directory]
      • Mount information
        1. /etc/fstab
        2. /etc/mtab
4. File Types
   1. Ordinary files
   2. Directories
   3. Symbolic (soft) links
   4. Special files: device files

Relevant Commands and Files