Changing Raid Type w/o Reinstalling

Joshua Daniel Franklin joshua at iocc.com
Tue Dec 31 08:59:00 CST 2002


What kind of backups do you do? This info might be helpful.

Last week I asked about bootable removable media (floppy or CD)
with the best tools for restoring a backup from tape. Specifically
I had a PE1400SC running RH7.2 moving to hardware RAID and restoring
a full dump from a DDS4 drive. 

There are many great tools (including the RH CD's rescue mode which
works well for simple rescues):

ftp://ftp.redhat.de/pub/rh-addons/rescue-cd/	RedHat SysAdmin Survival CD 
http://www.knopper.net/knoppix/			Knoppix Live Linux on CD
http://www.microwerks.net/~hugo/		Mondo Disaster Recovery CD
http://www.lnx-bbc.org/				Bootable Business Card CD
http://www.toms.net/rb/				Tom's Root Boot Floppy Disk

I liked the RedHat SysAdmin Survival CD best for a few reasons:
1. RedHat system (vs. for example Knoppix has a somewhat different layout)
2. Included needed tools (2.4 kernel/drivers, mt, dump/restore)
3. Comfortable environment (bash shell, networking, etc.)

The ISO and source can be downloaded at

ftp://ftp.redhat.de/pub/rh-addons/rescue-cd/

(It is in English. The reason it's on ftp.redhat.de rather than
ftp.redhat.com is simply because it's been developed exclusively by the
development team in .de)

I really wish that RedHat was more vocal about the existance of this
great tool. It appears to be used mainly for support cases. 

The most helpful response I received was from Jochen Schmidt
jochen dot schmidt at nospam millenux dot com

He recommended the RH Sysadmin CD and sent along this useful checklist.
While coming up with one's own checklist is trivial it is nice to have
a way to make sure you didn't forget anything.

--------------------------------------------------------------------------------
With minimal downtime it's not very easy.
Here is the way i use for moving data between machines:

0. configure Hardwareraid, Install System Management Partition
1. boot the new machine with the RedHat Sysadmin survial CD (alternative 
use Knoppix - http://knoppix.com/)
2. partition the new system for your need. 
3. format the new partitions
4. mount the partitions e.g.
        - mkdir /mnt/newsystem
        - mount  <new /> to /mnt/newsystem
        - mkdir /mnt/newsystem/boot
        - mount <new /boot> to /mnt/newsystem/boot
        - mkdir /mnt/newsystem/tmp
        - mkdir /mnt/newsystem/dev
        - mkdir /mnt/newsystem/dev/shm
        - mkdir /mnt/newsystem/dev/pts
        - mkdir /mnt/newsystem/proc
5. now create a /tmp/exclude - file on the *old* machine
------------------------------------------------
/proc
/dev/pts
/dev/shm
/tmp
< insert variable System-Data e.g. Mail-Spool-Dir here>
------------------------------------------------
If you move a webserver there are usually no variable Systemdata. If you 
are moving a mailserver, you should exclude the mailspool here!

6. configure the network on the new machine to an unused IP-Address.
7. start sshd on the new machine: /etc/init.d/sshd start
7a. set root-password (needed for knoppix!): passwd
8. test ssh from the old to the new machine.
works?
no! -> Check Ethernet, Network Device Driver -> 6.
yes -> 9.
9. on the *old* machine use tar to pipe the data thru a ssh Session to the 
new machine:
root at old:/ # cd /
ame-owner -X /tmp/exclude"
--->>> type the root-Passwort on the new machine.
--->>> wait until all data have copied.
10. go to the new machine.
11. check /mnt/newsystem/etc/fstab - If you use Redhat CREATE THE E2LABELS!
12. check /mnt/newsystem/etc/modules.conf
13. If you use an Hardware-Raid, you *must* build a new initrd.
13a chroot /mnt/newsystem
13b mkinitrd --withmodule=raidmodulename /boot/initrd-Kernel-XYZ.img Kernel-XYZ
13c exit
14. check /mnt/newsystem/etc/lilo.conf grub.conf or whatever
15. run your bootloader-Install "chroot /mnt/newsystem lilo -v"
16. DISCONNECT network to the NEW machine.
17. reboot the new machine
18. the machine should boot normaly. Kudzu should remove non-existant 
    hardware and should add new hardware.
19. check if you new system may work.
20. change the IP on the new system to a unused one (ifconfig)
21. connect network to the new machine.
22. shutdown services on the old machine
22a shutdown services on the new machine (if they started)
23. Move variable Data (e.g.) mailspool to the new machine:
root at old:/ # cd /
root at old:/ # tar cSf - /var/spool/mail | ssh newmachineip "cd / ; tar xSvpf - --same-owner"
--->>> type the root-Passwort on the new machine.
--->>> wait until all data have copied.
24. disconnect the old system from the network
25. on the new System run "service network restart" to setup the network
26. start your needed services
27. enjoy.

Hope this help

Jochen 


--------------------------------------------------------------------------------
My original query:

On Mon, 2002-12-23 at 13:10, Joshua Daniel Franklin wrote:
> I am planning for moving a RedHat 7.2 installation on a PowerEdge
> 1400SC over to hardware RAID. The machine has a DLT drive and less
> than 20GB of data on the current drive. I have the drives and a
> megaraid card all ready to go, and I am trying to determine the best
> way to backup/restore the data with minimal downtime.
> 
> I feel that dump/restore would be best but since the RedHat "linux rescue"
> mode does not have the "restore" command it looks like I would have to
> reinstall RH7.2 before doing the restore. That seems like a lot of time.
> I would like to be able to boot from removable media, create partitions,
> format, restore, done.
> 
> Does anyone have recommendations of available tools, or a better
> way to do this?
-- 
Joshua Daniel Franklin
Network Administrator
IOCC.COM

On Tue, 31 Dec 2002, Eric Wood wrote:

> I think that physically impossible.  Data bits are stripped across your 3+
> drives.  No one drive in you system has the "whole" picture.   You must
> reinstall.
> 
> -eric wood
> 
> ----- Original Message -----
> From: "Brian E. Seppanen" <seppy at chartermi.net>
> To: <linux-poweredge at dell.com>
> Sent: Tuesday, December 31, 2002 8:56 AM
> Subject: Changing Raid Type w/o Reinstalling
> 
> 
> > Hi Folks:
> >
> > Is it possible to change from Raid5 to Raid0 without necessarily
> > reinstalling the OS.  I have a 1650PE running RH7.3.     Can it be done
> > via FastCLI?   The server was reassigned as a proxy and raid5 is overkill,
> > I'd like to take my / and /usr partitions and reassign them as raid 0
> > instead of raid 5.
> >
> > Thanks,
> > Brian Seppanen
> > seppy at chartermi.net
> > 906-228-4226 ext 23
> >
> > _______________________________________________
> > Linux-PowerEdge mailing list
> > Linux-PowerEdge at dell.com
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> archives at http://lists.us.dell.com/htdig/
> 
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