Logical volumes

Setup

Give root reasonable disk space, 100G was default on ByteMark server

Creating logical volumes (`vgdisplay` to see volume groups)

lvcreate --name cpan --size 55G vg-hdds
lvcreate --name elasticsearch --size 83G vg-hdds
lvcreate --name metacpan-tmp --size 158G vg-hdds

Create metacpan-tmp filesystem (need LOTS of inodes)

mkfs.ext4 -i 4096 /dev/mapper/vg--hdds-metacpan--tmp

Check number of inodes = block clount

tune2fs -l /dev/mapper/vg--hdds-metacpan--tmp
Inode count:              41418752
Block count:              41418752

Then file systems for the rest

mkfs.ext4 /dev/mapper/vg--hdds-cpan
mkfs.ext4 /dev/mapper/vg--hdds-elasticsearch

Somewhere to mount

mkdir /mnt/lv-metacpan--tmp
mkdir /mnt/lv-cpan
mkdir /mnt/lv-elasticsearch

Edit /etc/fstab and add

/dev/mapper/vg--hdds-cpan         	  /mnt/lv-cpan ext4 defaults 0 2
/dev/mapper/vg--hdds-elasticsearch    /mnt/lv-elasticsearch ext4 defaults 0 2
/dev/mapper/vg--hdds-metacpan--tmp    /mnt/lv-metacpan--tmp   ext4 defaults 0 2

You probably want to sync from an existing machine

cd /mnt/lv-cpan
rsync -a -e ssh leo@bm-mc-02.metacpan.org:/mnt/lv-cpan/ ./

Extending space

To increase the space available on one of them, change the following example, which adds an additional 100 MB for the CPAN mirror. There's no need to unmount anything.

# Show current usage on virtual disk groups
pvscan
# Find the mapping you want
df
  or
ls /dev/mapper/
# Grow the LVM volume
lvextend -L +100M /dev/mapper/vg--hdds-cpan
# Extend the filesystem to the fit the new LV size
resize2fs /dev/mapper/vg--hdds-cpan

What to do if we get a box that doesn't have lvm, or a partition...

From: http://www.howtoforge.com/linux_lvm

apt-get install lvm2 dmsetup mdadm reiserfsprogs xfsprogs

(might get asked about 'arrays' - Leo tried to set to 'all')

Disk partitioning...

cfdisk /dev/sda

Add new logical partition
Set type to 8E - Linux LVM
Write (note the /dev/sdaXXX)

pvcreate /dev/sdaXXX

vgcreate vg-hdds /dev/sda5

Then follow instructions from above