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
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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.
