[TriLUG] How to migrate LVM to LVM on Raid-1
Rick DeNatale
rick.denatale at gmail.com
Thu Feb 16 13:26:31 EST 2006
Having just recovered from a failed SCSI hard drive, I'd now like to
put my second SCSI drive to work mirroring the first.
I've always had good backups of my user and config data, but it was
still a pain to get my machine back on it's feet.
When I replaced the drive, I re-installed Ubuntu 5.10 on /dev/sda using LVM.
The installer setup two partitions, one for /boot and another for an
LVM PV, and one VG with two LVs, one for /root and one for swap.
I'd now like to jack that up and install MDM software raid under it.
The Ubuntu kernel seems to be built with support for mdadm raid. I've
looked at a few how-tos but my head is still swimming and I'm, as
always leery of doing low-level drive operations. I've also backed up
/dev/sda using g4linux.
One page I've been studying is:
http://www.debian-administration.org/articles/238
It looks like the trick is to duplicate the partitioning of /dev/sda
on /dev/sdb after changing partition types to Linux raid autodetect,
and then do some mdmadmin magic to create a raid "device". I'm a
little nervous though when he starts making file systems on the raid
device, since I want to preserve the existing LVM setup and
filesystems on /dev/sda
If I'm reading some of the things I've found correctly, I might not
want to put the /boot partition in a raid cluster since grub seems to
have problems with that. If that's the case I guess I can manually
back it up as needed when new kernels get installed, perhaps using
rsync, yes?
I'm looking for some advice/encouragement
Here's my current setup. Note that there are also two large IDE
drives, one of these has partitions for /home and a shared user data
partition called /public, the other is used to store generational
backups using an rsync scheme based on Jason and Jeremy's backup talk
a few years back.
$ sudo sfdisk -l
Disk /dev/hdc: 19457 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/hdc1 0+ 1245 1246- 10008463+ 83 Linux
/dev/hdc2 1246 19456 18211 146279857+ 83 Linux
/dev/hdc3 0 - 0 0 0 Empty
/dev/hdc4 0 - 0 0 0 Empty
Disk /dev/hdd: 19457 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/hdd1 0+ 1 2- 16033+ 83 Linux
/dev/hdd2 2 4982 4981 40009882+ 83 Linux
/dev/hdd3 4983 9963 4981 40009882+ 83 Linux
/dev/hdd4 0 - 0 0 0 Empty
Disk /dev/sda: 1106 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sda1 * 0+ 30 31- 248976 83 Linux
/dev/sda2 31 1105 1075 8634937+ 5 Extended
/dev/sda3 0 - 0 0 0 Empty
/dev/sda4 0 - 0 0 0 Empty
/dev/sda5 31+ 1105 1075- 8634906 8e Linux LVM
Disk /dev/sdb: 1115 cylinders, 255 heads, 63 sectors/track
Units = cylinders of 8225280 bytes, blocks of 1024 bytes, counting from 0
Device Boot Start End #cyls #blocks Id System
/dev/sdb1 0 - 0 0 0 Empty
/dev/sdb2 0 - 0 0 0 Empty
/dev/sdb3 0 - 0 0 0 Empty
/dev/sdb4 0 - 0 0 0 Empty
Note that /dev/sdb is currently unused
$ mount
/dev/mapper/Ubuntu-root on / type ext3 (rw,errors=remount-ro)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
devpts on /dev/pts type devpts (rw,gid=5,mode=620)
tmpfs on /dev/shm type tmpfs (rw)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/sda1 on /boot type ext3 (rw)
/dev/hdd3 on /home type ext3 (rw)
/dev/hdd2 on /public type ext3 (rw)
/dev/hdc2 on /root/snapshot type ext3 (rw)
tmpfs on /dev type tmpfs (rw,size=10M,mode=0755)
nfsd on /proc/fs/nfsd type nfsd (rw)
$ sudo pvdisplay
--- Physical volume ---
PV Name /dev/sda5
VG Name Ubuntu
PV Size 8.23 GB / not usable 0
Allocatable yes (but full)
PE Size (KByte) 4096
Total PE 2108
Free PE 0
Allocated PE 2108
PV UUID v0S4TQ-YGh6-h1I9-nlq2-r53b-Eh04-ESjBTI
$ sudo vgdisplay
--- Volume group ---
VG Name Ubuntu
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 8.23 GB
PE Size 4.00 MB
Total PE 2108
Alloc PE / Size 2108 / 8.23 GB
Free PE / Size 0 / 0
VG UUID h4Xd2k-wH06-KjGJ-tKRo-oWp4-uk1T-q8pOMg
$ sudo lvdisplay
--- Logical volume ---
LV Name /dev/Ubuntu/root
VG Name Ubuntu
LV UUID iP9OI1-Qkw4-kbla-fwmg-ipnP-g80A-VAFxQD
LV Write Access read/write
LV Status available
# open 1
LV Size 7.86 GB
Current LE 2013
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:0
--- Logical volume ---
LV Name /dev/Ubuntu/swap_1
VG Name Ubuntu
LV UUID nudA40-pnMa-pjWv-0Flr-bIPM-dmcb-Q7KwXp
LV Write Access read/write
LV Status available
# open 1
LV Size 380.00 MB
Current LE 95
Segments 1
Allocation inherit
Read ahead sectors 0
Block device 254:1
--
Rick DeNatale
Visit the Project Mercury Wiki Site
http://www.mercuryspacecraft.com/
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