Building RAID1 on Fedora 11: can it be possible when it has LVM system?

[yu xintian]

Hi, all ! I have a Fedora 11 on my server . It has already been running for a month . I want to have RAID 1 on this server.But it has LVM on it ,so I can not be sure if I will lose some data as I want to use the second hard disk as a backup disk .Here is some details of my server:
fdisk -l

Disk /dev/sda: 80.0 GB, 80000000000 bytes
255 heads, 63 sectors/track, 9726 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000ac83c

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26        9726    77919263+  8e  Linux LVM

Disk /dev/sdb: 80.0 GB, 80000000000 bytes
255 heads, 63 sectors/track, 9726 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00003fed

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1        9726    78124063+  8e  Linux LVM

Disk /dev/dm-0: 157.6 GB, 157672275968 bytes
255 heads, 63 sectors/track, 19169 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-0 doesn't contain a valid partition table

Disk /dev/dm-1: 2113 MB, 2113929216 bytes
255 heads, 63 sectors/track, 257 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00000000

Disk /dev/dm-1 doesn't contain a valid partition table

df -h

dev/mapper/vg_shenzhem-lv_root
                      145G   28G  116G  19% /
/dev/sda1             194M   30M  155M  16% /boot
tmpfs                 498M  112K  498M   1% /dev/shm

I think I need to disable LVM first ,but some of the files maybe can not be mount .I followed it like this:
http://www.howtoforge.com/set-up-rai...system-fedora8
But this gentleman just copy data from sda to sdb , I cannot do that,I think it will overwrite some data on sdb. Does anybody have any idea about this?
I think I should be careful .I need to fully know the result before I take the next step.The data in the server is really inportant.
Any advice is welcome.
Thank you !

[SlowJet]

In that link, to me, it looks like the author re-invented the lvconvert command manually, then delt with the boot, and finally changed the dual LVM back to md hardware (probably fakeraid) raid1 with only 1 LVM on top, which is the desired metod for having raid 1 redunducy and LVM flexablity.

SO to answer your question with a question (because I do not have any raid to experiment with),
Do you have hardware raid, and can you change the setting (bios setup?) to raid 1 for an exiting single drive?

If not you can use lvconvert to make LVM raid 1, but it is really not the same, has several options and configurations, and needs spare (hot) LE's/PE's on demand for replacing a mirror side. Plus it would do noting for /boot.

See man lvconvert
man lvcreate (--mirrors 1 --corelog --mirrorlog[disk : core])

I'm looking at man for F13 so F11 may be different.

SJ

[yu xintian]

Well ,SlowJet. That Guide in www.howtoforge.org does not work for me .I failed ,and need to reinstall the system. What a bad luck !!!!!