Linux LVM Insights with case

Lvm

Logical Volume Management LVM is a system tool for hard disks. No matter in Linux or other similar system, it is very useful. Traditional partitions use fixed-size partitioning, which is cumbersome to resize. However, LVM can create and manage "logical" volumes, rather than using physical hard disks directly. The administrator's flexible management of logical volumes can be scaled down and simple to operate without damaging the stored data. You can add a new hard disk to the LVM at will to directly extend the logical volume that already exists. LVM does not require a reboot to let the kernel know that the partition exists.

LVM Online parsing: Http://baike.baidu.com/view/361916.htm?fr=aladdin

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LVM only common commands

& nbsp	Create		< Span style= "Color:rgb (0,176,80);" > delete
Physical volume	Pvcreate	Pvdisplay	Pvremove	*	*
Volume Group	Vgcreate	Vgdisplay	Vgremove	Vgextend	Vgreduce
Logical volumes	Lvcreate	Lvdisplay	Lvremove	Lvextend	Lvreduce

Access path to LV:

1,/dev/vg_name/lv_name

Eg:/dev/myvg/mylv

2,/dev/mapper/vg_name-lv_name

Eg:/dev/mapper/myvg-mylv

both of these are symbolic links, pointing to a file of/dev/dm-#

Reduction is dangerous!!!

reduce to Offline

1. Determine the target size after reduction, and ensure that there is enough space in the corresponding target logical volume size to accommodate all the previous numbers how to extend the logical volume:

2, first sanction the file system, and to perform mandatory testing

E2fsck-f

3. Reduce logical boundaries

RESIZE2FS DEVICE

4. Reduce physical boundaries

Lvreduce

DD If=/dev/zero of=/dev/sdb bs=512 count=1

/dev/null: Swallow all the data and discard it directly

/dev/zero: Bubble machine, Spit Zero

DD If=/dev/sdb of=/backup/mbr.backup Bs=1 count=512

Can be used for experimental filling

LVM Test Instructions

Create a disk partition by using FDISK. We need to create 3 2G partitions and do not require the partition to be of the same size. Similarly, partitions need to use the '8e' type to make them available for LVM.

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Repeat the above action to create the other two partitions. After partition creation is complete, we should have the following output:

Partx-a/dev/sdb

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Create physical volume (PV)

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Create a volume group (VG)

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Create a logical volume (LV)

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Now that the logical volume is ready, we can format and mount the logical volume, just like any other EXT2/3/4 partition!

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Mount and view

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This article is from the "Broken Saber" blog, please be sure to keep this source http://90sec.blog.51cto.com/7404127/1439705