はじめに
OpenWrtのrootfsをUSBメモリで拡張する方法でrootfsを拡張しましたが、いろいろ欲張ろうとするとメモリ不足になるので、更にUSBメモリでswapを確保することにしました。
ルータはGL.iNet GL-AR150を利用しています。
参考：
OSバージョンを確認します
root@OpenWrt:~# cat /etc/openwrt_release
DISTRIB_ID='OpenWrt'
DISTRIB_RELEASE='18.06.1'
DISTRIB_REVISION='r7258-5eb055306f'
DISTRIB_TARGET='ar71xx/generic'
DISTRIB_ARCH='mips_24kc'
DISTRIB_DESCRIPTION='OpenWrt 18.06.1 r7258-5eb055306f'
DISTRIB_TAINTS=''
必要なパッケージをインストールします
root@GL-AR150:~# opkg update
root@GL-AR150:~# opkg install kmod-usb-storage usbutils gdisk block-mount e2fsprogs kmod-fs-ext4
root@GL-AR150:~# reboot
USBメモリ(/dev/sda)をフォーマットします
#####
現在のシステム設定を確認します
root@OpenWrt:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 2560 2560 0 100% /rom
tmpfs 30160 420 29740 1% /tmp
/dev/mtdblock5 12288 2196 10092 18% /overlay
overlayfs:/overlay 12288 2196 10092 18% /
tmpfs 512 0 512 0% /dev
root@OpenWrt:~# dmesg | grep sd
[ 16.101834] random: ubusd: uninitialized urandom read (4 bytes read)
[ 16.109496] random: ubusd: uninitialized urandom read (4 bytes read)
[ 16.201745] random: ubusd: uninitialized urandom read (4 bytes read)
[ 156.982667] sd 0:0:0:0: [sda] 15633408 512-byte logical blocks: (8.00 GB/7.45 GiB)
[ 156.991501] sd 0:0:0:0: [sda] Write Protect is off
[ 156.995029] sd 0:0:0:0: [sda] Mode Sense: 43 00 00 00
[ 157.001802] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 157.036142] sda: sda1
[ 157.045232] sd 0:0:0:0: [sda] Attached SCSI disk
#####
フォーマットを開始します
root@OpenWrt:~# gdisk /dev/sda
GPT fdisk (gdisk) version 1.0.3
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Command (? for help): p
Disk /dev/sda: 15633408 sectors, 7.5 GiB
Model: Cruzer Fit
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 6478B437-EECD-AA48-A2EC-56C50B396DFD
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 15633374
Partitions will be aligned on 2048-sector boundaries
Total free space is 2014 sectors (1007.0 KiB)
Number Start (sector) End (sector) Size Code Name
1 2048 15633374 7.5 GiB 8300 Linux filesystem
#####
既存パーテイションを削除します
Command (? for help): d
Using 1
Command (? for help): p
Disk /dev/sda: 15633408 sectors, 7.5 GiB
Model: Cruzer Fit
Sector size (logical/physical): 512/512 bytes
Disk identifier (GUID): 6478B437-EECD-AA48-A2EC-56C50B396DFD
Partition table holds up to 128 entries
Main partition table begins at sector 2 and ends at sector 33
First usable sector is 34, last usable sector is 15633374
Partitions will be aligned on 2048-sector boundaries
Total free space is 15633341 sectors (7.5 GiB)
Number Start (sector) End (sector) Size Code Name
#####
rootfs用パーティションを作成します
Command (? for help): n
Partition number (1-128, default 1):
First sector (34-15633374, default = 2048) or {+-}size{KMGTP}:
Last sector (2048-15633374, default = 15633374) or {+-}size{KMGTP}: +7G
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300):
Changed type of partition to 'Linux filesystem'
#####
swap用パーティションを作成します
Command (? for help): n
Partition number (2-128, default 2):
First sector (34-15633374, default = 14682112) or {+-}size{KMGTP}:
Last sector (14682112-15633374, default = 15633374) or {+-}size{KMGTP}:
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): 8200
Changed type of partition to 'Linux swap'
#####
設定内容を保存します
Command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): Y
OK; writing new GUID partition table (GPT) to /dev/sda.
The operation has completed successfully.
#####
rootfs用ファイル・システムを作成します
root@OpenWrt:~# mkfs.ext4 /dev/sda1
mke2fs 1.44.1 (24-Mar-2018)
/dev/sda1 contains a ext4 file system
last mounted on /tmp/extroot/overlay on Thu Jan 1 09:00:13 1970
Proceed anyway? (y,N) y
Creating filesystem with 1835008 4k blocks and 458752 inodes
Filesystem UUID: 6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8
Superblock backups stored on blocks:
32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632
Allocating group tables: done
Writing inode tables: done
Creating journal (16384 blocks): done
Writing superblocks and filesystem accounting information: done
#####
swap用ファイル・システムを作成します
root@OpenWrt:~# mkswap /dev/sda2
Setting up swapspace version 1, size = 487042560 bytes
#####
設定内容を確認します
root@OpenWrt:~# block info | grep "/dev/sd"
/dev/sda1: UUID="6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8" VERSION="1.0" TYPE="ext4"
/dev/sda2: VERSION="1" TYPE="swap"
root@OpenWrt:~# block detect
config 'global'
option anon_swap '0'
option anon_mount '0'
option auto_swap '1'
option auto_mount '1'
option delay_root '5'
option check_fs '0'
config 'mount'
option target '/mnt/sda1'
option uuid '6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8'
option enabled '0'
config 'swap'
option device '/dev/sda2'
option enabled '0'
システム起動時に/dev/sda1と/dev/sda2を自動マウントするようにします
#####fstabを変更します
root@OpenWrt:~# block detect > /etc/config/fstab
root@OpenWrt:~# uci set fstab.@mount[0].enabled='1'
root@OpenWrt:~# uci set fstab.@swap[0].enabled='1'
root@OpenWrt:~# uci commit
#####再起動します
root@OpenWrt:~# reboot
#####自動マウントできました
root@OpenWrt:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 2560 2560 0 100% /rom
tmpfs 30160 420 29740 1% /tmp
/dev/mtdblock5 12288 2196 10092 18% /overlay
overlayfs:/overlay 12288 2196 10092 18% /
tmpfs 512 0 512 0% /dev
/dev/sda1 7159288 32244 6743660 0% /mnt/sda1
root@OpenWrt:~# uci show fstab
fstab.@global[0]=global
fstab.@global[0].anon_swap='0'
fstab.@global[0].anon_mount='0'
fstab.@global[0].auto_swap='1'
fstab.@global[0].auto_mount='1'
fstab.@global[0].delay_root='5'
fstab.@global[0].check_fs='0'
fstab.@mount[0]=mount
fstab.@mount[0].target='/mnt/sda1'
fstab.@mount[0].uuid='6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8'
fstab.@mount[0].enabled='1'
fstab.@swap[0]=swap
fstab.@swap[0].device='/dev/sda2'
fstab.@swap[0].enabled='1'
root@OpenWrt:~# block info
/dev/mtdblock4: UUID="9e82422c-eee4f4a6-d814e9ad-6c8c5a7c" VERSION="4.0" MOUNT="/rom" TYPE="squashfs"
/dev/mtdblock5: MOUNT="/overlay" TYPE="jffs2"
/dev/sda1: UUID="6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8" VERSION="1.0" MOUNT="/mnt/sda1" TYPE="ext4"
/dev/sda2: VERSION="1" TYPE="swap"
/dev/sda1をrootfsに切り替え、/dev/sda2でswapを確保します
#####現在のrootfs(/overlay)を/mnt/sda1にコピーします
root@OpenWrt:~# tar -C /overlay -cvf - . | tar -C /mnt/sda1 -xf -
#####fstabを変更します
root@OpenWrt:~# block detect > /etc/config/fstab
root@OpenWrt:~# sed -i s/option$'\t'enabled$'\t'\'0\'/option$'\t'enabled$'\t'\'1\'/ /etc/config/fstab
root@OpenWrt:~# sed -i s#/mnt/sda1#/overlay# /etc/config/fstab
root@OpenWrt:~# cat /etc/config/fstab
config 'global'
option anon_swap '0'
option anon_mount '0'
option auto_swap '1'
option auto_mount '1'
option delay_root '5'
option check_fs '0'
config 'mount'
option target '/overlay'
option uuid '6c7a2efd-414b-4f7d-a0f1-1d24eabc69d8'
option enabled '1'
config 'swap'
option device '/dev/sda2'
option enabled '1'
#####再起動します
root@OpenWrt:~# reboot
できました
root@OpenWrt:~# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/root 2560 2560 0 100% /rom
tmpfs 30160 412 29748 1% /tmp
/dev/sda1 7159288 36624 6739280 1% /overlay
overlayfs:/overlay 7159288 36624 6739280 1% /
tmpfs 512 0 512 0% /dev
/dev/sda1 7159288 36624 6739280 1% /mnt/sda1
root@OpenWrt:~# free
total used free shared buffers cached
Mem: 60320 25112 35208 412 3780 7724
-/+ buffers/cache: 13608 46712
Swap: 475624 0 475624