Here's the text file I put together for tonight's presentation.
I hope many found the presentation useful. I have certainly come to the
conclusion that most Desktop/Laptop systems should be using LVM. As we
saw tonight, supporting RAID is fairly trivial, once you learn the ins
and outs of msadm.
Chuck
Here are the steps needed to create LVM on a single device:
I am using /dev/sde (a USB flash drive) for this example.
More information can be found in /usr/share/doc/HOWTO/en-txt/LVM-HOWTO.gz
Steps:
1. Create any needed partitions on the drive (ex. /dev/sde1).
Note: A drive can support both traditional and LVM partitions simultaneously.
Note: You can use any partitioning utility to partition the device(s).
2. Create the Physical Volumes (PV) on the device. Run:
(The documentation strongly recommends that only one Physical Volume (PV)
exist on a single spindle.)
Note: Run `man pvcreate` for more information.
# pvcreate /dev/sde1
3. Create the Volume Groups (VG) on the PV. Run:
Note: Run `man vgcreate` for more information.
# vgcreate VG_NAME /dev/sde1
4. Create one or more Logical Volumes (LV), adding them to the VG created
above. Run:
Note: Run `man lvcreate` for more information.
# lvcreate -L64M -ndemoLV1 VG01
# lvcreate -L100M -ndemoLV2 VG01
5. Check the existence of the VG and the associated LVs. Run:
# ls -l /dev/VG01/
total 0
lrwxrwxrwx 1 root root 24 2006-08-03 14:40 demoLV1 ->
/dev/mapper/VG01-demoLV1
lrwxrwxrwx 1 root root 24 2006-08-03 14:42 demoLV2 ->
/dev/mapper/VG01-demoLV2
# ls -l /dev/mapper/
total 0
crw-rw---- 1 root root 10, 63 2006-08-03 13:45 control
brw-rw---- 1 root disk 253, 0 2006-08-03 14:52 VG01-demoLV1
brw-rw---- 1 root disk 253, 1 2006-08-03 14:53 VG01-demoLV2
6. Create file-systems (FS) on the LVs. Run:
Note: Run `man mke2fs` for more information.
# mke2fs /dev/VG01/demoLV1
# mke2fs /dev/VG01/demoLV2
7. Mount the FSs as you would any other block device. Run:
# mount /dev/VG01/demoLV1 /media/usb1
# mount /dev/VG01/demoLV2 /media/usb2
8. Check the stats of the mounted FSs. Run:
# mount
/dev/hda6 on / type ext3 (rw,errors=remount-ro)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
usbfs on /proc/bus/usb type usbfs (rw)
tmpfs on /dev/shm type tmpfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
/dev/hda3 on /boot type ext3 (rw)
tmpfs on /dev type tmpfs (rw,size=10M,mode=0755)
/dev/mapper/VG01-demoLV1 on /media/usb1 type ext2 (rw)
/dev/mapper/VG01-demoLV2 on /media/usb2 type ext2 (rw)
# df -h
Filesystem Size Used Avail Use% Mounted
on
/dev/hda6 21G 5.7G 14G 29% /
tmpfs 347M 0 347M 0% /dev/shm
/dev/hda3 964M 43M 869M 5% /boot
tmpfs 10M 160K 9.9M 2% /dev
/dev/mapper/VG01-demoLV1 62M 13K 59M 1%
/media/usb1
/dev/mapper/VG01-demoLV2 97M 13K 92M 1%
/media/usb2
9. Use e2fsadm to shrink or grow the file-systems and their underlying LVs.
Note: You can only grow a mounted FS/LV. You must unmount the FS in order to
shrink the FS and LV.
Note: Run `man e2fsadm` for more information.
For setting up LVM on a RAID system, the RAID must be built first.
1. Create the RAID. Here I am using RAID Level 5, with 4 devices and no spares.
Note: I'm using the first partition on each of 4 USB Flash drives: /dev/sda,
/dev/sdb, /dev/sdc, and /dev/sdd.
Run:
# mdadm --create --chunk=32 --level=5 --raid-devices=4
--parity=left-symmetric \
--auto=yes --spare-devices=0 --name=usbRAID /dev/md0 /dev/sda1 /dev/sdb1
/dev/sdc1 /dev/sdd1
2. Checking the RAID device. Run:
# ls -l /dev/md0
brw-rw---- 1 root disk 9, 0 2006-08-03 16:18 /dev/md0
3. Follow the above steps for creating the LVM volumes as above.
