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1 | [[chapter_lvm]] | |
2 | Logical Volume Manager (LVM) | |
3 | ---------------------------- | |
4 | ifdef::wiki[] | |
5 | :pve-toplevel: | |
6 | endif::wiki[] | |
7 | ||
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 lets 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: | |
14 | ||
15 | ---- | |
16 | # pvs | |
17 | PV VG Fmt Attr PSize PFree | |
18 | /dev/sda3 pve lvm2 a-- 7.87g 876.00m | |
19 | ||
20 | # vgs | |
21 | VG #PV #LV #SN Attr VSize VFree | |
22 | pve 1 3 0 wz--n- 7.87g 876.00m | |
23 | ---- | |
24 | ||
25 | The installer allocates three **L**ogical **V**olumes (LV) inside this | |
26 | VG: | |
27 | ||
28 | ---- | |
29 | # lvs | |
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 | |
34 | ---- | |
35 | ||
36 | root:: Formatted as `ext4`, and contains the operating system. | |
37 | ||
38 | swap:: Swap partition | |
39 | ||
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. | |
43 | ||
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`. | |
46 | ||
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. | |
50 | ||
51 | Hardware | |
52 | ~~~~~~~~ | |
53 | ||
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). | |
57 | ||
58 | LVM itself does not need any special hardware, and memory requirements | |
59 | are very low. | |
60 | ||
61 | ||
62 | Bootloader | |
63 | ~~~~~~~~~~ | |
64 | ||
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 and to | |
68 | apply xref:sysadmin_firmware_persistent[persistent firmware updates] from the | |
69 | user space. | |
70 | ||
71 | ||
72 | Creating a Volume Group | |
73 | ~~~~~~~~~~~~~~~~~~~~~~~ | |
74 | ||
75 | Let's assume we have an empty disk `/dev/sdb`, onto which we want to | |
76 | create a volume group named ``vmdata''. | |
77 | ||
78 | CAUTION: Please note that the following commands will destroy all | |
79 | existing data on `/dev/sdb`. | |
80 | ||
81 | First create a partition. | |
82 | ||
83 | # sgdisk -N 1 /dev/sdb | |
84 | ||
85 | ||
86 | Create a **P**hysical **V**olume (PV) without confirmation and 250K | |
87 | metadatasize. | |
88 | ||
89 | # pvcreate --metadatasize 250k -y -ff /dev/sdb1 | |
90 | ||
91 | ||
92 | Create a volume group named ``vmdata'' on `/dev/sdb1` | |
93 | ||
94 | # vgcreate vmdata /dev/sdb1 | |
95 | ||
96 | ||
97 | Creating an extra LV for `/var/lib/vz` | |
98 | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | |
99 | ||
100 | This can be easily done by creating a new thin LV. | |
101 | ||
102 | # lvcreate -n <Name> -V <Size[M,G,T]> <VG>/<LVThin_pool> | |
103 | ||
104 | A real world example: | |
105 | ||
106 | # lvcreate -n vz -V 10G pve/data | |
107 | ||
108 | Now a filesystem must be created on the LV. | |
109 | ||
110 | # mkfs.ext4 /dev/pve/vz | |
111 | ||
112 | At last this has to be mounted. | |
113 | ||
114 | WARNING: be sure that `/var/lib/vz` is empty. On a default | |
115 | installation it's not. | |
116 | ||
117 | To make it always accessible add the following line in `/etc/fstab`. | |
118 | ||
119 | # echo '/dev/pve/vz /var/lib/vz ext4 defaults 0 2' >> /etc/fstab | |
120 | ||
121 | ||
122 | Resizing the thin pool | |
123 | ~~~~~~~~~~~~~~~~~~~~~~ | |
124 | ||
125 | Resize the LV and the metadata pool with the following command: | |
126 | ||
127 | # lvresize --size +<size[\M,G,T]> --poolmetadatasize +<size[\M,G]> <VG>/<LVThin_pool> | |
128 | ||
129 | NOTE: When extending the data pool, the metadata pool must also be | |
130 | extended. | |
131 | ||
132 | ||
133 | Create a LVM-thin pool | |
134 | ~~~~~~~~~~~~~~~~~~~~~~ | |
135 | ||
136 | A thin pool has to be created on top of a volume group. | |
137 | How to create a volume group see Section LVM. | |
138 | ||
139 | # lvcreate -L 80G -T -n vmstore vmdata |