Understanding Disk Layout (Storage)

Understanding Partitions in Computer Systems

Introduction to Partitions

  • Partitions are crucial components that allow for the allocation of disk space on a computer's boot disk.

  • Understanding how partitions are structured and function is essential for effective storage management.

UEFI and Boot Process

  • UEFI (Unified Extensible Firmware Interface):

    • Firmware used for booting computers.

    • The boot disk is identified and allocated at this level.

  • Metadata:

    • The first megabyte of the boot disk is reserved for metadata, which is essential for booting the system.

    • Metadata includes critical information about the system configuration and boot processes.

Master Boot Record (MBR) and Modern Implementations

  • Historical Context of MBR:

    • The Master Boot Record (MBR) contained boot information in the first 512 bytes of the disk.

    • In modern systems, MBR is often replaced or supplemented by UEFI technologies.

  • Protective MBR:

    • This may still exist on disks for legacy compatibility, but it is not necessarily used for booting.

    • The protective MBR primarily signifies that the disk is in use when it’s filled with this minimal boot information.

Partition Table Structure

  • Structure of Partition Table:

    • Beginning from byte 513 to 1,024, the partition table is stored.

    • Each entry in the partition table requires 120 bytes.

    • With a maximum of 128 partitions allowable, a total of 32 sectors (equivalent to 16 kilobytes) is required for storing the complete partition table.

Role of Partitions

  • Function of Partitions:

    • Partitions serve as primary entities responsible for managing disk space allocation.

    • Each operating system requires partitions, especially noting the necessity for a UEFI boot partition during the boot procedure.

  • UEFI Boot Partition:

    • This specific partition must be accessible by all operating systems and contain vital system information.

File Systems and Their Organization

  • Each partition is formatted with a file system, which organizes how files are stored.

  • In Linux systems, it is common practice to employ several partitions to:

    • Separate different types of files,

    • Utilize logical volumes for enhanced flexibility in storage management.

Partition Management in Server Installation

  • Creation of Partitions:

    • Partitions are typically created during the installation of a server.

  • Common Mount Points:

    • The following partitions are commonly configured during installation:

    • boot/efi: Initial firmware boot partition.

    • boot: Contains the kernel of the operating system.

    • / (root): Represents the root file system of the operating system.

    • Additional optional mounts such as /home (user directories) and /var (variable files).

    • Typically includes a swap partition for memory management.

Adaptive Partition Management

  • When additional disk devices are added, or if the size of virtual disks are increased, management of existing partitions may become necessary.

  • Efficient management of partitions is considered a critical topic for certifications such as RHCSA (Red Hat Certified System Administrator).

Conclusion and Next Steps

  • The management of storage and understanding of partitions is critical and will be explored more thoroughly in subsequent lessons, highlighting important concepts for successful server management.