2 Logical Volume Manager (LVM)
3 ----------------------------
8 Most people install {pve} directly on a local disk. The {pve}
9 installation CD offers several options for local disk management, and
10 the current default setup uses LVM. The installer let you select a
11 single disk for such setup, and uses that disk as physical volume for
12 the **V**olume **G**roup (VG) `pve`. The following output is from a
13 test installation using a small 8GB disk:
17 PV VG Fmt Attr PSize PFree
18 /dev/sda3 pve lvm2 a-- 7.87g 876.00m
21 VG #PV #LV #SN Attr VSize VFree
22 pve 1 3 0 wz--n- 7.87g 876.00m
25 The installer allocates three **L**ogical **V**olumes (LV) inside this
30 LV VG Attr LSize Pool Origin Data% Meta%
31 data pve twi-a-tz-- 4.38g 0.00 0.63
32 root pve -wi-ao---- 1.75g
33 swap pve -wi-ao---- 896.00m
36 root:: Formatted as `ext4`, and contains the operation system.
40 data:: This volume uses LVM-thin, and is used to store VM
41 images. LVM-thin is preferable for this task, because it offers
42 efficient support for snapshots and clones.
44 For {pve} versions up to 4.1, the installer creates a standard logical
45 volume called ``data'', which is mounted at `/var/lib/vz`.
47 Starting from version 4.2, the logical volume ``data'' is a LVM-thin pool,
48 used to store block based guest images, and `/var/lib/vz` is simply a
49 directory on the root file system.
54 We highly recommend to use a hardware RAID controller (with BBU) for
55 such setups. This increases performance, provides redundancy, and make
56 disk replacements easier (hot-pluggable).
58 LVM itself does not need any special hardware, and memory requirements
65 We install two boot loaders by default. The first partition contains
66 the standard GRUB boot loader. The second partition is an **E**FI **S**ystem
67 **P**artition (ESP), which makes it possible to boot on EFI systems.
70 Creating a Volume Group
71 ~~~~~~~~~~~~~~~~~~~~~~~
73 Let's assume we have an empty disk `/dev/sdb`, onto which we want to
74 create a volume group named ``vmdata''.
76 CAUTION: Please note that the following commands will destroy all
77 existing data on `/dev/sdb`.
79 First create a partition.
81 # sgdisk -N 1 /dev/sdb
84 Create a **P**hysical **V**olume (PV) without confirmation and 250K
87 # pvcreate --metadatasize 250k -y -ff /dev/sdb1
90 Create a volume group named ``vmdata'' on `/dev/sdb1`
92 # vgcreate vmdata /dev/sdb1
95 Creating an extra LV for `/var/lib/vz`
96 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
98 This can be easily done by creating a new thin LV.
100 # lvcreate -n <Name> -V <Size[M,G,T]> <VG>/<LVThin_pool>
102 A real world example:
104 # lvcreate -n vz -V 10G pve/data
106 Now a filesystem must be created on the LV.
108 # mkfs.ext4 /dev/pve/vz
110 At last this has to be mounted.
112 WARNING: be sure that `/var/lib/vz` is empty. On a default
113 installation it's not.
115 To make it always accessible add the following line in `/etc/fstab`.
117 # echo '/dev/pve/vz /var/lib/vz ext4 defaults 0 2' >> /etc/fstab
120 Resizing the thin pool
121 ~~~~~~~~~~~~~~~~~~~~~~
123 Resize the LV and the metadata pool can be achieved with the following
126 # lvresize --size +<size[\M,G,T]> --poolmetadatasize +<size[\M,G]> <VG>/<LVThin_pool>
128 NOTE: When extending the data pool, the metadata pool must also be
132 Create a LVM-thin pool
133 ~~~~~~~~~~~~~~~~~~~~~~
135 A thin pool has to be created on top of a volume group.
136 How to create a volume group see Section LVM.
138 # lvcreate -L 80G -T -n vmstore vmdata