lvm的设置.doc

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rootstation20 # fdisk /dev/sdaCommand (m for help): n#新建分区First cylinder (1320-2610, default 1320):Using default value 1320Last cylinder or +size or +sizeM or +sizeK (1320-2610, default 2610): +512M#分区大小512MCommand (m for help): nFirst cylinder (1383-2610, default 1383):Using default value 1383Last cylinder or +size or +sizeM or +sizeK (1383-2610, default 2610): +512MCommand (m for help): t#更改分区类型Partition number (1-9): 8Hex 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): tPartition number (1-9): 9Hex code (type L to list codes): 8eChanged 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.rootstation20 # partprobe /dev/sda#使分区立即分区而不需重启2,创建物理卷rootstation20 # pvcreate /dev/sda89 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-pvdisplay命令可以查看物理卷的详细信息rootstation20 # 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-fIi9CB3.创建卷组rootstation20 # vgcreate vg02 /dev/sda89 Volume group vg02 successfully created-可以使用vgdisplay查看卷组详细信息rootstation20 # 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-l7kE6S4,创建卷rootstation20 # 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rootstation20 # 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.rootstation20 # mkfs.ext3 /dev/vg02/lv02rootstation20 # mkdir /lvmrootstation20 # vim /etc/fstab/dev/vg02/lv02 /lvm ext3 defaults 0 0rootstation20 # mount arootstation20 # 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lvmrootstation20 # 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rootstation20 # resize2fs /dev/vg02/lv02resize2fs 1.39 (29-May-2006)Filesystem at /dev/vg02/lv02 is mounted on /lvm; on-line resizing requiredPerforming 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rootstation20 # df -h |grep lv/dev/mapper/vg02-lv02 788M 17M 734M 3% /lvm2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rootstation20 # umount /lvm/-扫描分区rootstation20 # e2fsck -f /dev/vg02/lv02e2fsck 1.39 (29-May-2006)Pass 1: Checking inodes, blocks, and sizesPass 2: Checking directory structurePass 3: Checking directory connectivityPass 4: Checking reference countsPass 5: Checking group summary information/dev/vg02/lv02: 11/104608 files (9.1% non-contiguous), 7571/204800 blocks-收缩文件系统rootstation20 # resize2fs /dev/vg02/lv02 500Mresize2fs 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rootstation20 # 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rootstation20 # mount -arootstation20 # 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rootstation20 # vgextend vg02 /dev/sda9-从卷组中移除pvrootstation20 #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rootstation20 # 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,rootstation20 # mkdir /mnt/snaproot