6.format

前言

在使用樹莓派利用SD卡啟動系統的過程中，如何配置一張新買的空SD卡也是一個必不可少的技能。本文主要是介紹如何將SD卡分成boot和root兩個分區，操作流程主要分為分區、格式化兩步

操作流程

- 分區
- 查看插入的SD卡情況，可以看出目前插入了一張32G（29G）的SD卡，系統分配給其的名字是/dev/sdb，目前存在1個分區，名字分別為/dev/sdb1，格式是W95 FAT32 (LBA)
  - - hsq@ares:~$ sudo fdisk -l Disk /dev/sdb: 29 GiB, 31104958464 bytes, 60751872 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x9c2d2e7a Device Boot Start End Sectors Size Id Type /dev/sdb1 * 8192 60751871 60743680 29G c W95 FAT32 (LBA)

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- - 操作分區信息前先卸載掉系統對SD卡的自動掛載
    - hsq@ares:~$ umount /media/hsq/kingston
  - 然後利用fdisk命令進行分區操作
    - hsq@ares:~$ sudo fdisk /dev/sdb Welcome to fdisk (util-linux 2.27.1). Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help): p #这里也可以查看SD卡分区情况 Disk /dev/sdb: 29 GiB, 31104958464 bytes, 60751872 sectors Units: sectors of 1 * 512 = 512 bytes #默认每个扇区0.5KB Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x9c2d2e7a Device Boot Start End Sectors Size Id Type /dev/sdb1 * 8192 60751871 60743680 29G c W95 FAT32 (LBA) Command (m for help): d#删除当前的分区，有几个分区就要运行几次d Selected partition 1 Partition 1 has been deleted. Command (m for help): n #创建一个新的分区作为boot分区 Partition type p primary (0 primary, 0 extended, 4 free) e extended (container for logical partitions) Select (default p): #一般用默认的主分区即可 Using default response p. Partition number (1-4, default 1): #分区号默认按序即可 First sector (2048-60751871, default 2048): #起始扇区序号默认即可 Last sector, +sectors or +size{K,M,G,T,P} (2048-60751871, default 60751871): 205824 #终止扇区序号，2000个扇区是1MB，这里与初始扇区差值约为100MB Created a new partition 1 of type 'Linux' and of size 99.5 MiB. Command (m for help): t #改变分区类型 Partition type (type L to list all types): L #打印所有的支持类型，很长这里省略 ······ ······ ······ Partition type (type L to list all types): c #选择类型c，即W95 FAT32 (LBA)作为boot类型 Changed type of partition 'Linux' to 'W95 FAT32 (LBA)'. Command (m for help): n #再创建一个分区作为root分区 Partition type p primary (1 primary, 0 extended, 3 free) e extended (container for logical partitions) Select (default p): #默认 Using default response p. Partition number (2-4, default 2): #默认 First sector (205825-60751871, default 206848): #默认 Last sector, +sectors or +size{K,M,G,T,P} (206848-60751871, default 60751871): #默认把剩下所有的空间都分配给root Created a new partition 2 of type 'Linux' and of size 28.9 GiB. Command (m for help): p #查看一下重新分区后的信息 Disk /dev/sdb: 29 GiB, 31104958464 bytes, 60751872 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disklabel type: dos Disk identifier: 0x9c2d2e7a Device Boot Start End Sectors Size Id Type /dev/sdb1 2048 205824 203777 99.5M c W95 FAT32 (LBA) /dev/sdb2 206848 60751871 60545024 28.9G 83 Linux Command (m for help): w #保存分区信息，注意需要之前卸载掉系统对SD卡的自动挂载，否则这里会有一个警告 The partition table has been altered. Calling ioctl() to re-read partition table. Syncing disks.

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- 格式化
- 分區後還要對SD卡的各個分區進行格式化和重命名
  - - hsq@ares:~$ sudo mkfs.msdos /dev/sdb1 -n boot #将第一个分区sdb1格式化为fat类型，并重命名为boot mkfs.fat 3.0.28 (2015-05-16) mkfs.fat: warning - lowercase labels might not work properly with DOS or Windows hsq@ares:~$ sudo mkfs.ext4 /dev/sdb2 -L root #将第二个分区sdb2格式化为ext4类型，并重命名为root mke2fs 1.42.13 (17-May-2015) Creating filesystem with 7568128 4k blocks and 1892352 inodes Filesystem UUID: 9702d479-9bc1-4c72-9398-70d018b9fbd5 Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208, 4096000 Allocating group tables: done Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done

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問題解決

- 問題：用fdisk命令分區結束後w保存時出現警告
- 錯誤提示：Re-reading the partition table failed.:Device or resource busy
- 原因分析：因為用fdisk命令前沒有卸載系統自動掛載的SD
- 解決：umount /media /hsq/kingston
- 問題：掛載分區雖然成功但是有報警告
- 錯誤提示：Volume was not properly unmounted
- 原因分析：多次意外掉電造成的。據說可以把分區文件夾的權限設置為只讀而避免這個問題，沒驗證過
- 解決：在ubuntu主機上用以下命令修復。參考
  - - fsck.fat -V /dev/mmcblk0p1
- 問題：
- 錯誤提示：
- 原因分析：
- 解決：

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