lvm(逻辑卷的管理)

 

lvm的设置 原理: LVM:logical volume manager(逻辑卷管理) LVM可以随意拉伸和缩小，SCSI的硬盘最多只能够分15个区，如果需要更多的分区，怎么办呢，如果分区在规划的时候分小了或者大了，怎么办呢，而LVM很好的就解决了这些问题。 下面开始进行LVM逻辑卷创建的讨论 从上面这个图可以看到，创建逻辑卷的步骤： Linux分区----------物理卷-----------卷组-----------逻辑卷   1,首先:新建两个分区512M,类型为lvm的分区 [root@station20 ~]# fdisk /dev/sda Command (m for help): n                            ##新建分区 First cylinder (1320-2610, default 1320): Using default value 1320 Last cylinder or +size or +sizeM or +sizeK (1320-2610, default 2610): +512M       #分区大小512M Command (m for help): n First cylinder (1383-2610, default 1383): Using default value 1383 Last cylinder or +size or +sizeM or +sizeK (1383-2610, default 2610): +512M Command (m for help): t                   ##更改分区类型 Partition number (1-9): 8 Hex code (type L to list codes): 8e            ##8e的类型为LVM具体类型可输入L查询 Changed system type of partition 8 to 8e (Linux LVM) Command (m for help): t Partition number (1-9): 9 Hex code (type L to list codes): 8e Changed system type of partition 9 to 8e (Linux LVM) Command (m for help): w                           ##保存并退出 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. Syncing disks. [root@station20 ~]# partprobe /dev/sda                 #使分区立即分区而不需重启 2,创建物理卷 [root@station20 ~]# pvcreate /dev/sda[89]  Wiping software RAID md superblock on /dev/sda8  Physical volume "/dev/sda8" successfully created  Wiping software RAID md superblock on /dev/sda9  Physical volume "/dev/sda9" successfully created -------------àpvdisplay命令可以查看物理卷的详细信息 [root@station20 ~]# pvdisplay  "/dev/sda9" is a new physical volume of "494.16 MB"  --- NEW Physical volume ---  PV Name               /dev/sda9  VG Name  PV Size               494.16 MB  Allocatable           NO  PE Size (KByte)       0  Total PE              0  Free PE               0  Allocated PE          0  PV UUID               BWWolQ-A0Pz-gGD7-zbqu-qoWS-fXyw-uiIETV  "/dev/sda8" is a new physical volume of "494.16 MB"  --- NEW Physical volume ---  PV Name               /dev/sda8  VG Name  PV Size               494.16 MB  Allocatable           NO  PE Size (KByte)       0  Total PE              0   Free PE               0  Allocated PE          0  PV UUID               EewF0N-7X1z-SRnI-WW7A-WrlR-V0aY-fIi9CB 3.创建卷组 [root@station20 ~]# vgcreate vg02 /dev/sda[89]  Volume group "vg02" successfully created -----------------可以使用vgdisplay查看卷组详细信息 [root@station20 ~]# vgdisplay  --- Volume group ---  VG Name               vg02  System ID  Format                lvm2  Metadata Areas        2  Metadata Sequence No 1  VG Access             read/write  VG Status             resizable  MAX LV                0  Cur LV                0  Open LV               0  Max PV                0  Cur PV                2  Act PV                2  VG Size               984.00 MB  PE Size               4.00 MB  Total PE              246  Alloc PE / Size       0 / 0  Free PE / Size       246 / 984.00 MB  VG UUID               tDd40t-fDoU-ocJo-dFyt-4A4a-xrbr-l7kE6S 4,创建卷 [root@station20 ~]# lvcreate -L 700M -n lv02 vg02   (参数L指定大小,n指定名字)  Logical volume "lv02" created -------------同样也可使用lvdisplay命令查看lvm详细信息 [root@station20 ~]# lvdisplay /dev/vg02/lv02  --- Logical volume ---  LV Name                /dev/vg02/lv02  VG Name                vg02  LV UUID                zrNmph-jt9m-oQK0-NPoM-D23y-kZG4-Qx8vL2  LV Write Access        read/write  LV Status              available  # open                 0  LV Size                700.00 MB  Current LE             175  Segments               2  Allocation             inherit  Read ahead sectors     auto  - currently set to     256  Block device           253:1 ---------格式化lvm分区并挂载在/lvm中使用且每次开机都生效. [root@station20 ~]# mkfs.ext3 /dev/vg02/lv02 [root@station20 ~]# mkdir /lvm [root@station20 ~]# vim /etc/fstab /dev/vg02/lv02          /lvm                    ext3    defaults        0 0 [root@station20 ~]# mount –a [root@station20 ~]# df –h |grep lv /dev/mapper/vg02-lv02                       689M   17M 638M   3% /lvm 二lvm拉伸与收缩 1,拉伸操作可以在线完成. -----------拉伸lvm [root@station20 ~]# lvextend -L 800M /dev/vg02/lv02  Extending logical volume lv02 to 800.00 MB  Logical volume lv02 successfully resized -----------拉伸文件系统 [root@station20 ~]# resize2fs /dev/vg02/lv02 resize2fs 1.39 (29-May-2006) Filesystem at /dev/vg02/lv02 is mounted on /lvm; on-line resizing required Performing an on-line resize of /dev/vg02/lv02 to 204800 (4k) blocks. The filesystem on /dev/vg02/lv02 is now 204800 blocks long. ----------df查看效果 [root@station20 ~]# df -h |grep lv /dev/mapper/vg02-lv02                       788M   17M 734M   3% /lvm 2收缩lvm需要离线操作,而且要严格按照步骤完成,不然影响远大. --------------首先卸载分区 [root@station20 ~]# umount /lvm/ -------------扫描分区 [root@station20 ~]# e2fsck -f /dev/vg02/lv02 e2fsck 1.39 (29-May-2006) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/vg02/lv02: 11/104608 files (9.1% non-contiguous), 7571/204800 blocks ---------------收缩文件系统 [root@station20 ~]# resize2fs /dev/vg02/lv02 500M resize2fs 1.39 (29-May-2006) Resizing the filesystem on /dev/vg02/lv02 to 128000 (4k) blocks. The filesystem on /dev/vg02/lv02 is now 128000 blocks long. ---------------收缩lvm分区 [root@station20 ~]# lvreduce -L 500M /dev/vg02/lv02  WARNING: Reducing active logical volume to 500.00 MB  THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce lv02? [y/n]: y  Reducing logical volume lv02 to 500.00 MB  Logical volume lv02 successfully resized -------------重新挂载并查看效果 [root@station20 ~]# mount -a [root@station20 ~]# df -h |grep lv /dev/mapper/vg02-lv02                       493M   17M 457M   4% /lvm 最后最好重启测试. 简述一下其他命令 --------------添加一个pv进卷组 [root@station20 ~]# vgextend vg02 /dev/sda9 --------------从卷组中移除pv [root@station20 ~]#vgreduce vg02 /dev/sda9 具体命令请参照-------------man page 三.lvm快照的功能 优点是速度快,快速备份,保持一致性 具体命令 [root@station20 ~]# lvcreate -L 200M -s -n snaplv2 /dev/vg02/lv02  Logical volume "snaplv2" created 这样创建快照完成了,可以只读挂载对分区进行备份, [root@station20 ~]# mkdir /mnt/snap [root@station20 ~]# mount -o ro /dev/vg02/snaplv2 /mnt/snap/ 备份完之后就可以移除快照了 [root@station20 ~]# umount /mnt/snap/ [root@station20 ~]# lvremove /dev/vg02/snaplv2 Do you really want to remove active logical volume snaplv2? [y/n]: y  Logical volume "snaplv2" successfully removed LVM基本研究在这里