63 lines
No EOL
2.5 KiB
Markdown
63 lines
No EOL
2.5 KiB
Markdown
---
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tags:
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- Linux
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- Operating_Systems
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---
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# Disks
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A disk is a mass storage [device](./Devices.md) which we can write to and read from.
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## SCSI
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* Small Computer System Interface
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* Pronounced _scuzzy_.
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* It is a protocol that allows communicaton between printers, scanners and other peripherals in addition to harddisks.
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* The `/sda/` device that is the most common designation for the harddisk in Linux systems stands for *SCSI disk*.
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## Disk schematic
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The following diagram represents the basic anatomy of a disk device.
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* A disk is divided up into *partitions* which are subsections of the overall disk. The kernel presents each partition as a [block device](./Devices.md#Devices.md) as it would with an entire disk.
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* The disk dedicates a small part of its contents to a *partition table*: this defines the different partitions that comprise the total disk space.
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* The *filesystem* is a database of files and directories: this comprises the bulk of the partition and is of course what you interact with in [user space](./User_Space.md) when reading and writing data.
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## Partitioning disks
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### Viewing current partitions
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Whenever you install a Linux distribution on a real or virtual machine, you must partition the drive. There are three main tools that people choose from: `parted`, `g(raphical)parted`, `fdisk`.
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We can use `parted -l` to view the partition table for the current machine:
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```bash
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Model: SKHynix_HFS512GDE9X081N (nvme)
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Disk /dev/nvme0n1: 512GB
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Sector size (logical/physical): 512B/512B
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Partition Table: gpt
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Disk Flags:
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Number Start End Size File system Name Flags
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1 1049kB 513MB 512MB fat32 boot, esp
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2 513MB 30.5GB 30.0GB ext4
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3 30.5GB 512GB 482GB ext4
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```
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We can use `fdisk -l` to get slightly more info:
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```bash
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disk /dev/nvme0n1: 476.94 GiB, 512110190592 bytes, 1000215216 sectors
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Disk model: SKHynix_HFS512GDE9X081N
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Units: sectors of 1 * 512 = 512 bytes
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Sector size (logical/physical): 512 bytes / 512 bytes
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I/O size (minimum/optimal): 512 bytes / 512 bytes
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Disklabel type: gpt
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Disk identifier: 08175E77-CB9F-C34A-9032-DF29A3F8F0FE
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Device Start End Sectors Size Type
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/dev/nvme0n1p1 2048 1001471 999424 488M EFI System
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/dev/nvme0n1p2 1001472 59594751 58593280 27.9G Linux filesystem
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/dev/nvme0n1p3 59594752 1000214527 940619776 448.5G Linux filesystem
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```
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So my main harddrive is `/dev/nvme0n1` and it has the standard three partitions:
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* Boot partition (`/dev/nvme0n1p1`)
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* Root dir (`/dev/nvme0n1p2`)
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* Home dir (`/dev/nvme0n1p3`) |