Linux Centos虛擬機擴容（/dev/mapper/centos-root）

場景

我們在使用linux虛擬機時會經常出現空間不夠用的情況，下面主要分享下如何增加VMWare虛擬機(Linux)的根目錄磁盤空間

實踐

1、在虛擬機軟件上,為對應的虛擬機擴充20G硬盤空間.

2、啟用該虛擬機，使用Linux的fdisk分區工具給磁盤分區

[root@Agile936 ~]# fdisk -lDisk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 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 Disk label type: dos Disk identifier: 0x000f0195Device Boot Start End Blocks Id System /dev/sda1 * 2048 2099199 1048576 83 Linux /dev/sda2 2099200 52428799 25164800 8e Linux LVMDisk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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[root@Agile936 ~]#

根據提示可以看到此系統的磁盤接口為scsi，對應‘sda’，下面進行分區.

• 輸入m查看幫助信息，
• 再輸入n(表示增加分區)，
• 回車后輸入p(創建主分區)，
• 回車后partition number輸入3(因為上面已經有兩個分區sda1和sda2)，
• 回車會提示輸入分區的start值(通過fdisk -l 可以看出sda2的end值為40960)，我們可以指定start值為40961，end值為默認即可(即當前最大值)，
• 回車后輸入W進行保存，分區劃分完畢。

[root@Agile936 ~]# fdisk /dev/sda 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.Command (m for help): n #表示增加分區 Partition type:p primary (2 primary, 0 extended, 2 free)e extended Select (default p): p # 創建主分區 Partition number (3,4, default 3): 3 First sector (52428800-104857599, default 52428800): Using default value 52428800 Last sector, +sectors or +size{K,M,G} (52428800-104857599, default 104857599): Using default value 104857599 Partition 3 of type Linux and of size 25 GiB is setCommand (m for help): w The partition table has been altered!Calling ioctl() to re-read partition table.WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks.

查看當前分區情況:

[root@Agile936 ~]# fdisk -lDisk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 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 Disk label type: dos Disk identifier: 0x000f0195Device Boot Start End Blocks Id System /dev/sda1 * 2048 2099199 1048576 83 Linux /dev/sda2 2099200 52428799 25164800 8e Linux LVM /dev/sda3 52428800 104857599 26214400 83 LinuxDisk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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

可以看到/dev/sda3的Id號為83，我們要將其改成8e(LVM卷文件系統的Id)，具體方法同上，如下圖所示：

[root@Agile936 ~]# fdisk /dev/sda 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.Command (m for help): t Partition number (1-3, default 3): 3 Hex code (type L to list all codes): L0 Empty 24 NEC DOS 81 Minix / old Lin bf Solaris1 FAT12 27 Hidden NTFS Win 82 Linux swap / So c1 DRDOS/sec (FAT-2 XENIX root 39 Plan 9 83 Linux c4 DRDOS/sec (FAT-3 XENIX usr 3c PartitionMagic 84 OS/2 hidden C: c6 DRDOS/sec (FAT-4 FAT16 <32M 40 Venix 80286 85 Linux extended c7 Syrinx5 Extended 41 PPC PReP Boot 86 NTFS volume set da Non-FS data6 FAT16 42 SFS 87 NTFS volume set db CP/M / CTOS / .7 HPFS/NTFS/exFAT 4d QNX4.x 88 Linux plaintext de Dell Utility8 AIX 4e QNX4.x 2nd part 8e Linux LVM df BootIt9 AIX bootable 4f QNX4.x 3rd part 93 Amoeba e1 DOS accessa OS/2 Boot Manag 50 OnTrack DM 94 Amoeba BBT e3 DOS R/Ob W95 FAT32 51 OnTrack DM6 Aux 9f BSD/OS e4 SpeedStorc W95 FAT32 (LBA) 52 CP/M a0 IBM Thinkpad hi eb BeOS fse W95 FAT16 (LBA) 53 OnTrack DM6 Aux a5 FreeBSD ee GPTf W95 Ext'd (LBA) 54 OnTrackDM6 a6 OpenBSD ef EFI (FAT-12/16/ 10 OPUS 55 EZ-Drive a7 NeXTSTEP f0 Linux/PA-RISC b 11 Hidden FAT12 56 Golden Bow a8 Darwin UFS f1 SpeedStor 12 Compaq diagnost 5c Priam Edisk a9 NetBSD f4 SpeedStor 14 Hidden FAT16 <3 61 SpeedStor ab Darwin boot f2 DOS secondary 16 Hidden FAT16 63 GNU HURD or Sys af HFS / HFS+ fb VMware VMFS 17 Hidden HPFS/NTF 64 Novell Netware b7 BSDI fs fc VMware VMKCORE 18 AST SmartSleep 65 Novell Netware b8 BSDI swap fd Linux raid auto 1b Hidden W95 FAT3 70 DiskSecure Mult bb Boot Wizard hid fe LANstep 1c Hidden W95 FAT3 75 PC/IX be Solaris boot ff BBT 1e Hidden W95 FAT1 80 Old Minix Hex code (type L to list all codes): 8e Changed type of partition 'Linux' to 'Linux LVM'Command (m for help): w The partition table has been altered!Calling ioctl() to re-read partition table.WARNING: Re-reading the partition table failed with error 16: Device or resource busy. The kernel still uses the old table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8) Syncing disks.

重啟后,查看最新的分區,修改成功

[root@Agile936 ~]# fdisk -lDisk /dev/sda: 53.7 GB, 53687091200 bytes, 104857600 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 Disk label type: dos Disk identifier: 0x000f0195Device Boot Start End Blocks Id System /dev/sda1 * 2048 2099199 1048576 83 Linux /dev/sda2 2099200 52428799 25164800 8e Linux LVM /dev/sda3 52428800 104857599 26214400 8e Linux LVMDisk /dev/mapper/centos-root: 23.6 GB, 23613931520 bytes, 46120960 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytesDisk /dev/mapper/centos-swap: 2147 MB, 2147483648 bytes, 4194304 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

3、擴展文件系統

將該分區創建為文件系統：

[root@Agile936 ~]# mkfs.ext4 /dev/sda3 mke2fs 1.42.9 (28-Dec-2013) Filesystem label= OS type: Linux Block size=4096 (log=2) Fragment size=4096 (log=2) Stride=0 blocks, Stripe width=0 blocks 1638400 inodes, 6553600 blocks 327680 blocks (5.00%) reserved for the super user First data block=0 Maximum filesystem blocks=2155872256 200 block groups 32768 blocks per group, 32768 fragments per group 8192 inodes per group Superblock backups stored on blocks:32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208,4096000Allocating group tables: done Writing inode tables: done Creating journal (32768 blocks): done Writing superblocks and filesystem accounting information: done

創建PV:

pvdisplay當前的物理卷

[root@Agile936 ~]# pvdisplay--- Physical volume ---PV Name /dev/sda2VG Name centosPV Size <24.00 GiB / not usable 3.00 MiBAllocatable yesPE Size 4.00 MiBTotal PE 6143Free PE 1Allocated PE 6142PV UUID WjHxHP-WmJh-MXl7-qixZ-EGJY-pFxb-MeJK88

pvcreate指令用于將物理硬盤分區初始化為物理卷，以便被LVM使用。要創建物理卷必須首先對硬盤進行分區，并且將硬盤分區的類型設置為“8e”后，才能使用pvcreat指令將分區初始化為物理卷。

[root@Agile936 ~]# pvcreate /dev/sda3 WARNING: ext4 signature detected on /dev/sda3 at offset 1080. Wipe it? [y/n]: yWiping ext4 signature on /dev/sda3.Physical volume "/dev/sda3" successfully created. [root@Agile936 ~]# pvdisplay--- Physical volume ---PV Name /dev/sda2VG Name centosPV Size <24.00 GiB / not usable 3.00 MiBAllocatable yesPE Size 4.00 MiBTotal PE 6143Free PE 1Allocated PE 6142PV UUID WjHxHP-WmJh-MXl7-qixZ-EGJY-pFxb-MeJK88"/dev/sda3" is a new physical volume of "25.00 GiB"--- NEW Physical volume ---PV Name /dev/sda3VG NamePV Size 25.00 GiBAllocatable NOPE Size 0Total PE 0Free PE 0Allocated PE 0PV UUID lM84VY-OQEa-qwf3-OyO6-W4bm-UNxk-Az6wRb

擴展VG:

當前需要擴充的lvm組名，可以通過vgdisplay查看：

[root@Agile936 ~]# vgdisplay--- Volume group ---VG Name centosSystem IDFormat lvm2Metadata Areas 1Metadata Sequence No 3VG Access read/writeVG Status resizableMAX LV 0Cur LV 2Open LV 2Max PV 0Cur PV 1Act PV 1VG Size <24.00 GiBPE Size 4.00 MiBTotal PE 6143Alloc PE / Size 6142 / 23.99 GiBFree PE / Size 1 / 4.00 MiBVG UUID FWHNlT-utQu-jqv5-ukto-POcw-YOY5-9thDL8

vgextend指令用于動態的擴展卷組，它通過向卷組中添加物理卷來增加卷組的容量,可以看出可擴展的空間為24GB，接下來進行LV擴展，擴展空間要小于VG 的Free PE的大小，即小于24GB。

[root@Agile936 ~]# vgextend centos /dev/sda3Volume group "centos" successfully extended [root@Agile936 ~]# vgdisplay--- Volume group ---VG Name centosSystem IDFormat lvm2Metadata Areas 2Metadata Sequence No 4VG Access read/writeVG Status resizableMAX LV 0Cur LV 2Open LV 2Max PV 0Cur PV 2Act PV 2VG Size 48.99 GiBPE Size 4.00 MiBTotal PE 12542Alloc PE / Size 6142 / 23.99 GiBFree PE / Size 6400 / 25.00 GiBVG UUID FWHNlT-utQu-jqv5-ukto-POcw-YOY5-9thDL8

lvextend命令用于擴展空間，如下面將root分區擴展22GB。

[root@Agile936 ~]# lvextend -L +22G /dev/mapper/centos-rootSize of logical volume centos/root changed from 21.99 GiB (5630 extents) to 43.99 GiB (11262 extents).Logical volume centos/root successfully resized.

命令使系統重新讀取大小, 添加成功

[root@Agile936 ~]# xfs_growfs /dev/mapper/centos-root meta-data=/dev/mapper/centos-root isize=512 agcount=4, agsize=1441280 blks= sectsz=512 attr=2, projid32bit=1= crc=1 finobt=0 spinodes=0 data = bsize=4096 blocks=5765120, imaxpct=25= sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal bsize=4096 blocks=2815, version=2= sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 data blocks changed from 5765120 to 11532288 [root@Agile936 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/centos-root 44G 4.2G 40G 10% / devtmpfs 2.0G 0 2.0G 0% /dev tmpfs 2.0G 0 2.0G 0% /dev/shm tmpfs 2.0G 8.6M 2.0G 1% /run tmpfs 2.0G 0 2.0G 0% /sys/fs/cgroup /dev/sda1 1014M 143M 872M 15% /boot tmpfs 407M 0 407M 0% /run/user/0

總結

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