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139 lines
3.6 KiB
Plaintext
139 lines
3.6 KiB
Plaintext
[[chapter_lvm]]
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Logical Volume Manager (LVM)
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----------------------------
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ifdef::wiki[]
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:pve-toplevel:
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endif::wiki[]
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Most people install {pve} directly on a local disk. The {pve}
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installation CD offers several options for local disk management, and
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the current default setup uses LVM. The installer let you select a
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single disk for such setup, and uses that disk as physical volume for
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the **V**olume **G**roup (VG) `pve`. The following output is from a
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test installation using a small 8GB disk:
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----
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# pvs
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PV VG Fmt Attr PSize PFree
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/dev/sda3 pve lvm2 a-- 7.87g 876.00m
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# vgs
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VG #PV #LV #SN Attr VSize VFree
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pve 1 3 0 wz--n- 7.87g 876.00m
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----
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The installer allocates three **L**ogical **V**olumes (LV) inside this
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VG:
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----
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# lvs
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LV VG Attr LSize Pool Origin Data% Meta%
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data pve twi-a-tz-- 4.38g 0.00 0.63
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root pve -wi-ao---- 1.75g
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swap pve -wi-ao---- 896.00m
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----
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root:: Formatted as `ext4`, and contains the operating system.
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swap:: Swap partition
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data:: This volume uses LVM-thin, and is used to store VM
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images. LVM-thin is preferable for this task, because it offers
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efficient support for snapshots and clones.
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For {pve} versions up to 4.1, the installer creates a standard logical
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volume called ``data'', which is mounted at `/var/lib/vz`.
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Starting from version 4.2, the logical volume ``data'' is a LVM-thin pool,
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used to store block based guest images, and `/var/lib/vz` is simply a
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directory on the root file system.
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Hardware
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~~~~~~~~
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We highly recommend to use a hardware RAID controller (with BBU) for
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such setups. This increases performance, provides redundancy, and make
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disk replacements easier (hot-pluggable).
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LVM itself does not need any special hardware, and memory requirements
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are very low.
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Bootloader
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~~~~~~~~~~
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We install two boot loaders by default. The first partition contains
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the standard GRUB boot loader. The second partition is an **E**FI **S**ystem
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**P**artition (ESP), which makes it possible to boot on EFI systems.
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Creating a Volume Group
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~~~~~~~~~~~~~~~~~~~~~~~
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Let's assume we have an empty disk `/dev/sdb`, onto which we want to
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create a volume group named ``vmdata''.
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CAUTION: Please note that the following commands will destroy all
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existing data on `/dev/sdb`.
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First create a partition.
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# sgdisk -N 1 /dev/sdb
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Create a **P**hysical **V**olume (PV) without confirmation and 250K
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metadatasize.
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# pvcreate --metadatasize 250k -y -ff /dev/sdb1
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Create a volume group named ``vmdata'' on `/dev/sdb1`
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# vgcreate vmdata /dev/sdb1
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Creating an extra LV for `/var/lib/vz`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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This can be easily done by creating a new thin LV.
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# lvcreate -n <Name> -V <Size[M,G,T]> <VG>/<LVThin_pool>
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A real world example:
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# lvcreate -n vz -V 10G pve/data
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Now a filesystem must be created on the LV.
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# mkfs.ext4 /dev/pve/vz
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At last this has to be mounted.
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WARNING: be sure that `/var/lib/vz` is empty. On a default
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installation it's not.
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To make it always accessible add the following line in `/etc/fstab`.
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# echo '/dev/pve/vz /var/lib/vz ext4 defaults 0 2' >> /etc/fstab
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Resizing the thin pool
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~~~~~~~~~~~~~~~~~~~~~~
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Resize the LV and the metadata pool can be achieved with the following
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command.
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# lvresize --size +<size[\M,G,T]> --poolmetadatasize +<size[\M,G]> <VG>/<LVThin_pool>
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NOTE: When extending the data pool, the metadata pool must also be
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extended.
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Create a LVM-thin pool
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~~~~~~~~~~~~~~~~~~~~~~
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A thin pool has to be created on top of a volume group.
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How to create a volume group see Section LVM.
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# lvcreate -L 80G -T -n vmstore vmdata
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