page counter next up previous contents
Next: SWAP LV 放大縮小 Up: 邏輯卷冊管理 Previous: 開機自動掛載   Contents   DYWANG_HOME

SWAP 使用 LV

  1. 若要將 swap 的分割區也使用 LVM 管理，則可將整個硬碟的可用空間都分割為 /dev/vda4，並將格式設定為 8e (lvm)。 
    [root@kvm7 ~]# fdisk /dev/vda 
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): p

Disk /dev/vda: 4294 MB, 4294967296 bytes, 8388608 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: 0x00094fcc

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      411647      204800   83  Linux
/dev/vda2          411648     7579647     3584000   8e  Linux LVM
/dev/vda3         7579648     7845887      133120   8e  Linux LVM

Command (m for help): n 
Partition type:
   p   primary (3 primary, 0 extended, 1 free)
   e   extended
Select (default e): p
Selected partition 4
First sector (7845888-8388607, default 7845888): 
Using default value 7845888
Last sector, +sectors or +size{K,M,G} (7845888-8388607, default 8388607): 
Using default value 8388607
Partition 4 of type Linux and of size 265 MiB is set

Command (m for help): p

Disk /dev/vda: 4294 MB, 4294967296 bytes, 8388608 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: 0x00094fcc

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      411647      204800   83  Linux
/dev/vda2          411648     7579647     3584000   8e  Linux LVM
/dev/vda3         7579648     7845887      133120   8e  Linux LVM
/dev/vda4         7845888     8388607      271360   83  Linux

Command (m for help): t
Partition number (1-4, default 4): 
Hex code (type L to list all codes): 8e
Changed type of partition 'Linux' to 'Linux LVM'

Command (m for help): p

Disk /dev/vda: 4294 MB, 4294967296 bytes, 8388608 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: 0x00094fcc

   Device Boot      Start         End      Blocks   Id  System
/dev/vda1   *        2048      411647      204800   83  Linux
/dev/vda2          411648     7579647     3584000   8e  Linux LVM
/dev/vda3         7579648     7845887      133120   8e  Linux LVM
/dev/vda4         7845888     8388607      271360   8e  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.
  2. 偵測新的分割表。 
    [root@kvm7 ~]# partprobe 
[root@kvm7 ~]# kpartx /dev/vda
vda1 : 0 409600 /dev/vda 2048
vda2 : 0 7168000 /dev/vda 411648
vda3 : 0 266240 /dev/vda 7579648
vda4 : 0 542720 /dev/vda 7845888
  3. pvcreate 將 /dev/vda4 初始化為 LVM 的實體空間。 
    [root@kvm7 ~]# pvcreate /dev/vda4
  Physical volume "/dev/vda4" successfully created.
  4. 在 LVM 的實體空間 /dev/vda4 產生名為 vg_mntx，PE 大小為 4M 的 VG。 
    [root@kvm7 ~]# vgcreate -s 4M vg_mntx /dev/vda4
  Volume group "vg_mntx" successfully created
  5. 在 VG vg_mntx 中建立名為 pub，大小為 10 個 PE 的 LV。 
    [root@kvm7 ~]# lvcreate --extents 10 -n pub vg_mntx
  Logical volume "pub" created.
  6. 在 VG vg_mntx 中建立名為 swap，大小為 30M 的 LV，但因 VG 建立時指定的 PE 大小為 4M，LV 的大小必須是 PE 大小的倍數，因此自動加大到 32M。 
    [root@kvm7 ~]# lvcreate --size 30M -n swap vg_mntx
  Rounding up size to full physical extent 32.00 MiB
  Logical volume "swap" created.
  7. 將 LV /dev/vg_mntx-pub 依要求格式化，此例為 ext3。 
    [root@kvm7 ~]# mkfs.ext3 /dev/vg_mntx/pub 
mke2fs 1.42.9 (28-Dec-2013)
Filesystem label=
OS type: Linux
Block size=1024 (log=0)
Fragment size=1024 (log=0)
Stride=0 blocks, Stripe width=0 blocks
10240 inodes, 40960 blocks
2048 blocks (5.00%) reserved for the super user
First data block=1
Maximum filesystem blocks=41943040
5 block groups
8192 blocks per group, 8192 fragments per group
2048 inodes per group
Superblock backups stored on blocks: 
	8193, 24577

Allocating group tables: done                            
Writing inode tables: done                            
Creating journal (4096 blocks): done
Writing superblocks and filesystem accounting information: done
  8. 將 LV /dev/vg_mntx-swap 格式化 swap。 
    [root@kvm7 ~]# mkswap /dev/vg_mntx/swap 
Setting up swapspace version 1, size = 32764 KiB
no label, UUID=03be6480-7674-4fee-80fd-ebe573737927
  9. 在開機掛載表中，加入以下兩行，設定開機時將 LV vg_mnt-pub 掛載在 /mnt/pubx，及啟動 LV vg_mntx-swap swap。 
    [root@kvm7 ~]# vim /etc/fstab 
[root@kvm7 ~]# grep vg_mntx /etc/fstab
/dev/mapper/vg_mntx-pub    /mnt/pubx        ext3    defaults        1 2
/dev/mapper/vg_mntx-swap    swap            swap    defaults        0 0
  10. 依掛載表 /etc/fstab 指定的格式及目錄掛載所有檔案系統。 
    [root@kvm7 ~]# mount -a
  11. 查看掛載狀況，LV vg_mntx-pub 以 ext3 格式掛載在 /mnt/pubx。 
    [root@kvm7 ~]# df -TH
Filesystem                  Type      Size  Used Avail Use% Mounted on
devtmpfs                    devtmpfs  505M     0  505M   0% /dev
tmpfs                       tmpfs     520M     0  520M   0% /dev/shm
tmpfs                       tmpfs     520M  7.1M  513M   2% /run
tmpfs                       tmpfs     520M     0  520M   0% /sys/fs/cgroup
/dev/mapper/vg_kvm7usb-root ext4      3.3G  2.9G  198M  94% /
/dev/vda1                   xfs       207M  188M   19M  91% /boot
/dev/mapper/vg_kvm7home-vo  ext4       78M  1.7M   70M   3% /home
tmpfs                       tmpfs     104M     0  104M   0% /run/user/0
/dev/mapper/vg_mntx-pub     ext3       37M  521k   34M   2% /mnt/pubx
  12. 啟動掛載表 /etc/fstab 中設定的所有 swap。 
    [root@kvm7 ~]# swapon -a
  13. 查詢啟動的 swap，其中 /dev/dm-4 就是 LV vg_mntx-swap。 
    [root@kvm7 ~]# swapon -s
Filename          Type        Size    Used    Priority
/dev/dm-0         partition   126972  0       -1
/dev/dm-4         partition   32764   0       -2

[root@kvm7 ~]# ll /dev/mapper/
total 0
crw-------. 1 root root 10, 236 Nov  2 07:26 control
lrwxrwxrwx. 1 root root       7 Nov  2 07:26 vg_kvm7home-vo -> ../dm-2
lrwxrwxrwx. 1 root root       7 Nov  2 07:26 vg_kvm7usb-root -> ../dm-1
lrwxrwxrwx. 1 root root       7 Nov  2 07:26 vg_kvm7usb-swap -> ../dm-0
lrwxrwxrwx. 1 root root       7 Nov  2 07:33 vg_mntx-pub -> ../dm-3
lrwxrwxrwx. 1 root root       7 Nov  2 07:33 vg_mntx-swap -> ../dm-4