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1 | Logical Volume Manager (LVM) | |
2 | ---------------------------- | |
3 | ifdef::wiki[] | |
4 | :pve-toplevel: | |
5 | endif::wiki[] | |
6 | ||
7 | Most people install {pve} directly on a local disk. The {pve} | |
8 | installation CD offers several options for local disk management, and | |
9 | the current default setup uses LVM. The installer let you select a | |
10 | single disk for such setup, and uses that disk as physical volume for | |
11 | the **V**olume **G**roup (VG) `pve`. The following output is from a | |
12 | test installation using a small 8GB disk: | |
13 | ||
14 | ---- | |
15 | # pvs | |
16 | PV VG Fmt Attr PSize PFree | |
17 | /dev/sda3 pve lvm2 a-- 7.87g 876.00m | |
18 | ||
19 | # vgs | |
20 | VG #PV #LV #SN Attr VSize VFree | |
21 | pve 1 3 0 wz--n- 7.87g 876.00m | |
22 | ---- | |
23 | ||
24 | The installer allocates three **L**ogical **V**olumes (LV) inside this | |
25 | VG: | |
26 | ||
27 | ---- | |
28 | # lvs | |
29 | LV VG Attr LSize Pool Origin Data% Meta% | |
30 | data pve twi-a-tz-- 4.38g 0.00 0.63 | |
31 | root pve -wi-ao---- 1.75g | |
32 | swap pve -wi-ao---- 896.00m | |
33 | ---- | |
34 | ||
35 | root:: Formatted as `ext4`, and contains the operation system. | |
36 | ||
37 | swap:: Swap partition | |
38 | ||
39 | data:: This volume uses LVM-thin, and is used to store VM | |
40 | images. LVM-thin is preferable for this task, because it offers | |
41 | efficient support for snapshots and clones. | |
42 | ||
43 | For {pve} versions up to 4.1, the installer creates a standard logical | |
44 | volume called ``data'', which is mounted at `/var/lib/vz`. | |
45 | ||
46 | Starting from version 4.2, the logical volume ``data'' is a LVM-thin pool, | |
47 | used to store block based guest images, and `/var/lib/vz` is simply a | |
48 | directory on the root file system. | |
49 | ||
50 | Hardware | |
51 | ~~~~~~~~ | |
52 | ||
53 | We highly recommend to use a hardware RAID controller (with BBU) for | |
54 | such setups. This increases performance, provides redundancy, and make | |
55 | disk replacements easier (hot-pluggable). | |
56 | ||
57 | LVM itself does not need any special hardware, and memory requirements | |
58 | are very low. | |
59 | ||
60 | ||
61 | Bootloader | |
62 | ~~~~~~~~~~ | |
63 | ||
64 | We install two boot loaders by default. The first partition contains | |
65 | the standard GRUB boot loader. The second partition is an **E**FI **S**ystem | |
66 | **P**artition (ESP), which makes it possible to boot on EFI systems. | |
67 | ||
68 | ||
69 | Creating a Volume Group | |
70 | ~~~~~~~~~~~~~~~~~~~~~~~ | |
71 | ||
72 | Let's assume we have an empty disk `/dev/sdb`, onto which we want to | |
73 | create a volume group named ``vmdata''. | |
74 | ||
75 | CAUTION: Please note that the following commands will destroy all | |
76 | existing data on `/dev/sdb`. | |
77 | ||
78 | First create a partition. | |
79 | ||
80 | # sgdisk -N 1 /dev/sdb | |
81 | ||
82 | ||
83 | Create a **P**hysical **V**olume (PV) without confirmation and 250K | |
84 | metadatasize. | |
85 | ||
86 | # pvcreate --metadatasize 250k -y -ff /dev/sdb1 | |
87 | ||
88 | ||
89 | Create a volume group named ``vmdata'' on `/dev/sdb1` | |
90 | ||
91 | # vgcreate vmdata /dev/sdb1 | |
92 | ||
93 | ||
94 | Creating an extra LV for `/var/lib/vz` | |
95 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
96 | ||
97 | This can be easily done by creating a new thin LV. | |
98 | ||
99 | # lvcreate -n <Name> -V <Size[M,G,T]> <VG>/<LVThin_pool> | |
100 | ||
101 | A real world example: | |
102 | ||
103 | # lvcreate -n vz -V 10G pve/data | |
104 | ||
105 | Now a filesystem must be created on the LV. | |
106 | ||
107 | # mkfs.ext4 /dev/data/vz | |
108 | ||
109 | At last this has to be mounted. | |
110 | ||
111 | WARNING: be sure that `/var/lib/vz` is empty. On a default | |
112 | installation it's not. | |
113 | ||
114 | To make it always accessible add the following line in `/etc/fstab`. | |
115 | ||
116 | # echo '/dev/pve/vz /var/lib/vz ext4 defaults 0 2' >> /etc/fstab | |
117 | ||
118 | ||
119 | Resizing the thin pool | |
120 | ~~~~~~~~~~~~~~~~~~~~~~ | |
121 | ||
122 | Resize the LV and the metadata pool can be achieved with the following | |
123 | command. | |
124 | ||
125 | # lvresize --size +<size[\M,G,T]> --poolmetadatasize +<size[\M,G]> <VG>/<LVThin_pool> | |
126 | ||
127 | NOTE: When extending the data pool, the metadata pool must also be | |
128 | extended. | |
129 | ||
130 | ||
131 | Create a LVM-thin pool | |
132 | ~~~~~~~~~~~~~~~~~~~~~~ | |
133 | ||
134 | A thin pool has to be created on top of a volume group. | |
135 | How to create a volume group see Section LVM. | |
136 | ||
137 | # lvcreate -L 80G -T -n vmstore vmdata |