近两天，服务器突然报错：“No space left on device.”。刚开始并未放在心上。不期数日后，Apache服务器也宕掉了。无奈之下，只得着手解决。
由于报错是由于没有磁盘空间引起的，所以首先想到的是删除不要的文件。于是用以下命令对内核进行了清理。
package-cleanup --oldkernels同时，还删除了一些临时文件。不期数周之后，再底出现相同的报错。这令人不得不思考对硬盘进行物理扩展。本打算扩展一个内置硬盘，不想没有多余的硬盘接口。一番查询之后，入手了一个东芝6T的外置硬盘。
此外，就扩展方案来说，有两个选择。一是把现有硬盘上的“/Home”进行备份，再恢复到追加的硬盘上，然后把现有硬盘的“/Home”的空间分配给“/root”。这样做的风险是可能遇到恢复出错的问题。最终选择的方案是将追加硬盘分为两个区，分别对现有硬盘的“/home”和“/root”进行扩展。
1 确认硬盘信息
接入之后，首先确认硬盘信息。
# fdisk -l
# 硬盘信息
Disk /dev/sdb: 6001.2 GB, 6001175126016 bytes, 11721045168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/recommended): 4096 bytes / 4096 bytes
Disk label type: gpt
Disk identifier: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX2 对硬盘进行分区
确认硬盘为“/dev/sdb”后，接下来对硬盘进行分区。
# fdisk /dev/sdb
WARNING: fdisk GPT support is currently new, and therefore in an experimental phase. Use at your own discretion.
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
# 追加一个大小约为1T的分区
Command (help with m): n
Partition number (1-128, default 1):
First sector (34-11721045134, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-11721045134, default 11721045134): 2344209026
Created partition 1
# 追加一个大小约为5T的分区
Command (help with m): n
Partition number (2-128, default 2):
First sector (34-11721045134, default 2344210432):
Last sector, +sectors or +size{K,M,G,T,P} (2344210432-11721045134, default 11721045134):
Created partition 2
# 确认分区结果
Command (help with m): p
Disk /dev/sdb: 6001.2 GB, 6001175126016 bytes, 11721045168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/recommended): 4096 bytes / 4096 bytes
Disk label type: gpt
Disk identifier: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX
# Start End Size Type Name
1 2048 2344209026 1.1T Linux filesyste
2 2344210432 11721045134 4.4T Linux filesyste
# 保存分区结果
Command (help with m): w
The partition table has changed!
Call ioctl() to reload the partition table.
Synchronizing disk.3 创建物理卷
在创建物理卷之前，首先确认分区的创建结果和当前物理卷的信息。可以看到当前物理卷的大小。
# 确认分区结果
# ls /dev/sdb*
/dev/sdb /dev/sdb1 /dev/sdb2
# 确认当前物理卷的信息
# pvdisplay
--- Physical volume ---
PV Name /dev/sda6
VG Name centos
PV Size <288.73 GiB / not usable 3.00 MiB
Allocatable yes (but full)
PE Size 4.00 MiB
Total PE 73914
Free PE 0
Allocated PE 73914
PV UUID XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX接下来，创建两个分区的目的是为了同时扩展“/dev/mapper/centos-root”和“/dev/mapper/centos-home”。
# 创建物理卷 /dev/sdb1
# pvcreate /dev/sdb1
WARNING: xfs signature detected on /dev/sdb1 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/sdb1.
Physical volume "/dev/sdb1" successfully created.
# 创建物理卷 /dev/sdb2
# pvcreate /dev/sdb2
WARNING: xfs signature detected on /dev/sdb2 at offset 0. Wipe it? [y/n]: y
Wiping xfs signature on /dev/sdb2.
Physical volume "/dev/sdb2" successfully created.4 扩展现有分区
在对现有逻辑卷进行扩展前，先查看一下现有逻辑卷的信息。
# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:27 +0900
LV Status available
# open 2
LV Size 7.75 GiB
Current LE 1984
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:28 +0900
LV Status available
# open 1
LV Size 180.00 GiB
Current LE 46080
Segments 2
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:30 +0900
LV Status available
# open 1
LV Size 1.19 TiB
Current LE 312007
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
接下来将物理卷扩展到逻辑卷，并将扩展的逻辑卷分配给现有的逻辑卷。
# 将"/dev/sdb1"扩展到逻辑卷上
# vgextend centos /dev/sdb1
Volume group "centos" successfully extended
# 将扩展的逻辑卷100%分配给现有的逻辑卷"/dev/mapper/centos-root"
# lvextend -l +100%FREE /dev/mapper/centos-root
Size of logical volume centos/root changed from <100.98 GiB (25850 extents) to 1.19 TiB (312007 extents).
Logical volume centos/root successfully resized.
# 将"/dev/sdb2"扩展到逻辑卷上
# vgextend centos /dev/sdb2
Volume group "centos" successfully extended
# 将扩展的逻辑卷100%分配给现有的逻辑卷"/dev/mapper/centos-home"
# lvextend -l +100%FREE /dev/mapper/centos-home
Size of logical volume centos/home changed from 180.00 GiB (46080 extents) to 4.54 TiB (1190712 extents).
Logical volume centos/home successfully resized.
查看处理结果。从结果中可以看到，刚才创建的物理卷分别被分配给了逻辑卷“/dev/mapper/centos-root”和“/dev/mapper/centos-home”。
# lvdisplay
--- Logical volume ---
LV Path /dev/centos/swap
LV Name swap
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:27 +0900
LV Status available
# open 2
LV Size 7.75 GiB
Current LE 1984
Segments 1
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:1
--- Logical volume ---
LV Path /dev/centos/home
LV Name home
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:28 +0900
LV Status available
# open 1
LV Size 4.54 TiB
Current LE 1190712
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:2
--- Logical volume ---
LV Path /dev/centos/root
LV Name root
VG Name centos
LV UUID XXXXXX-XXXX-XXXX-XXXX-XXXX-XXXX-XXXXXX
LV Write Access read/write
LV Creation host, time localhost, XXXX-04-20 22:33:30 +0900
LV Status available
# open 1
LV Size 1.19 TiB
Current LE 312007
Segments 3
Allocation inherit
Read ahead sectors auto
- currently set to 256
Block device 253:0
5 将处理结果反映到文件系统
# 将扩展结果反映到文件系统"/dev/centos/root"上
# xfs_growfs /dev/centos/root
meta-data=/dev/mapper/centos-root isize=512 agcount=9, agsize=3276800 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=26470400, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=6400, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 26470400 to 319495168
# 将扩展结果反映到文件系统"/dev/centos/home"上
# xfs_growfs /dev/centos/home
meta-data=/dev/mapper/centos-home isize=512 agcount=4, agsize=11796480 blks
= sectsz=4096 attr=2, projid32bit=1
= crc=1 finobt=0 spinodes=0
data = bsize=4096 blocks=47185920, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal bsize=4096 blocks=23040, version=2
= sectsz=4096 sunit=1 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
data blocks changed from 47185920 to 1219289088以下是用”df”命令的确认结果。从中可以看到，”/root”和”/home”均被扩展到指定的大小。
# df -h
ファイルシス サイズ 使用 残り 使用% マウント位置
devtmpfs 7.7G 0 7.7G 0% /dev
tmpfs 7.7G 572K 7.7G 1% /dev/shm
tmpfs 7.7G 12M 7.7G 1% /run
tmpfs 7.7G 0 7.7G 0% /sys/fs/cgroup
/dev/mapper/centos-root 1.2T 99G 1.1T 9% /
/dev/loop2 45M 45M 0 100% /var/lib/snapd/snap/certbot/2913
/dev/loop0 54M 54M 0 100% /var/lib/snapd/snap/snapd/18933
/dev/loop3 64M 64M 0 100% /var/lib/snapd/snap/core20/1852
/dev/loop7 128K 128K 0 100% /var/lib/snapd/snap/bare/5
/dev/loop5 90M 90M 0 100% /var/lib/snapd/snap/lumi/199
/dev/loop6 165M 165M 0 100% /var/lib/snapd/snap/gnome-3-28-1804/198
/dev/loop1 92M 92M 0 100% /var/lib/snapd/snap/gtk-common-themes/1535
/dev/loop4 165M 165M 0 100% /var/lib/snapd/snap/gnome-3-28-1804/194
/dev/loop8 50M 50M 0 100% /var/lib/snapd/snap/snapd/18596
/dev/loop10 44M 44M 0 100% /var/lib/snapd/snap/certbot/2836
/dev/loop11 64M 64M 0 100% /var/lib/snapd/snap/core20/1828
/dev/loop12 56M 56M 0 100% /var/lib/snapd/snap/core18/2714
/dev/loop9 56M 56M 0 100% /var/lib/snapd/snap/core18/2721
/dev/sda5 1014M 206M 809M 21% /boot
/dev/sda2 96M 36M 61M 38% /boot/efi
/dev/mapper/centos-home 4.6T 13G 4.6T 1% /home
tmpfs 1.6G 72K 1.6G 1% /run/user/1000
tmpfs 1.6G 8.0K 1.6G 1% /run/user/0
tmpfs 1.6G 12K 1.6G 1% /run/user/426 检查文件系统类型
# cat /etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Apr 20 22:33:31 XXXX
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/centos-root / xfs defaults 0 0
UUID=XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX /boot xfs defaults 0 0
UUID=XXXX-XXXX /boot/efi vfat umask=0077,shortname=winnt 0 0
/dev/mapper/centos-home /home xfs defaults 0 0
/dev/mapper/centos-swap swap swap defaults 0 0