topic Re: Data Migrationf from server to server in Disk Enclosures

Data Migrationf from server to server

roadrunner_1 — Sun, 31 Aug 2003 14:57:18 GMT

I have the following scenario
server 1 - 400GB in 3 volume groups data LVM striped across a group of 4 disks and the LUNS are from a XP512.

I have to move these disks to another server. The data is primarily informix database. what would be the correct procedure..Please correct me if this procedure is wrong??

1. On server 1, vgexport to a mapfile
2. On server 2 perform ioscan and insf. Then vgimport the mapfile...

I am not sure if I am missing something here..Do I have to vgextend the disks before I do the vgimport.

RR

Re: Data Migrationf from server to server

Tim Adamson_1 — Sun, 31 Aug 2003 21:34:23 GMT

Sounds ok to me. You don't have to vgextend anything. But you do need to create the directory and group file for the vg.

# mkdir /dev/vg??
# mknod /dev/vg??/group c 64 0x0?0000

Tim

Re: Data Migrationf from server to server

Michael Tully — Sun, 31 Aug 2003 21:54:07 GMT

Hi RR,

The procedure is fairly simple, I've done this numerous times.
For each volume group. If you have more than 16 volume groups make sure that you increase your kernel parameter 'maxvgs'

original server (note the usage of the preview and shared options)
# vgexport -m myvg.mapfile -p -v -s /dev/myvg
Copy the mapfile(s) to the new server
Disconnect disk array
on new server
# mkdir /dev/myvg
# mknod /dev/myvg/group c 64 0x0?0000 (make sure that use unique numbering)
# vgimport -v -m myvg.mapfile -p -s /dev/myvg
if successful
# vgimport -v -m myvg.mapfile -s /dev/myvg
Check ownerships/permissions etc depending on how you have informix set up on the original server.
Make the necessary directories for mounting filesystems.
Make sure that informix has the same UID number.
Before mounting any directories onto mount points you must run 'fsck' on all of them.
Mount the directories and make sure you update the /etc/fstab file.
There is no need to run vgextend, as all of the volumes wll be included in the mapfile (-s option) which scan all of the LUN's for a matching VGID (volume group identifier)

Regards
Michael

Re: Data Migrationf from server to server

roadrunner_1 — Tue, 02 Sep 2003 14:28:33 GMT

What happens if the ports on the storage frame changes??
Example : Server1 CL1-C, CL2-C and CL1-E, CL2-E
Server 2: CL1-G, CL1-H and CL1-G, CL2-G

Would the vgimports still work??

RR

Re: Data Migrationf from server to server

Dave Wherry — Tue, 02 Sep 2003 15:31:55 GMT

It will work. The host knows nothing about the ports on the XP. As long as the LUN's are assigned to a port that server 2 can see, they will just look like available disks on an available path.

Re: Data Migrationf from server to server

roadrunner_1 — Tue, 02 Sep 2003 15:55:53 GMT

Doesnt the t#d# in C#t#d# changes if the storage ports are changed?? I am thinking that the t#d# are dependent on the LUN # and the c# depends on the host bus adaptor on the server side.
I guess the c#t#d# remains the same as long as the HBAs are in the same slot in both the servers..what happens if the HBA are in a different Hardware path on the second server??

Re: Data Migrationf from server to server

Michael Tully — Wed, 03 Sep 2003 03:08:42 GMT

Hi,

That's the beauty of using the -s option for vgexport and vgimport. The mapfile carries over the 'VGID' which is on every disk used in LVm. When you run the vgimport using the -s option it uses the VGID in the mapfile to match each and every LUN that it can scan, and creates a match. When it finds all of the matches it attempts to do the import. If it is successful, there will be no error messages. If there it will tell you. This may happen if it doesn't find all of the disks in the volume group. If you find that this happens then the server cannot see all of the disks it had before. When running the vgimport command always use the -p option (preview) the first time around.

Cheers
Michael

Re: Data Migrationf from server to server

roadrunner_1 — Sat, 20 Sep 2003 20:50:34 GMT

Thanks for all ur replies..I have one last question. If the LUN id changes when mapped to the ports on the storage frame connected to the new server B, will the vgimport still work.

RR