data migration from one san box to another san box

[mohan singh]

Hi folks,

we are migrating data from one san storage(EMC-DMX2000) to anthother san storage(EMC-DMX4)

Please be noted that data migration will be from one san box to another san box,
BUT SERVER REMAIN SAME(ONE),
I have gone thru the vgexport and vgimport docs, and prepared the procedure as below.

1- stop the application and database
2- unmount the file system
3- vgchange -a n vgxx
4a- vgexport -p -s -v -m vgxx.map /dev/vgxx
4b- vgexport -p -v -m vgxx.map /dev/vgxx
(which option I should use with -s or whithout -s in this scenario)
5- disconnect the old storage
6- present the new storage disk(LUN)to server or mask the disk
7-discover the disk
insf -e
ioscan -fn
8 vgexport vgxx (remove vgxx and entry from /etc/lvmtab
9 - mkdir /dev/vgxx
mknod /dev/vgxx/group c 64 0x0x0000
10a - vgimport -s -v -m vgxx.map /dev/vgxx
10b - vgimport -v -m vgxx.map /dev/vgxx
(which option should used in this scenario)
11 - vgchange -a y vgxx
12 - if required run fsck
13 - mount all file system

I am sure that most of you might have done this activity before , Can you please share your experience and verify the above procedure and share how you have done.

I also notice forum also taking about vgscan cammand .

Please share your experience , Points are waiting for you.
thanks in advance.
Regards
Mohan

[Pete Randall]

Your procedure, as described, really doesn't do anything but export (disconnect) your original SAN from the server and then attempt to import (connect) the new SAN. You don't state that the new storage has LVM structures already defined on it. If not, the import process won't even work.

Not only that, but this does nothing to move the data from one SAN to the other. What you need to do is present the new SAN, define LVM structures on it (pvcreate, vgcreate, lvcreate, etc., etc.) and then use some sort of backup/restore utility to actually move the data.


Pete

[Tim Nelson]

I have always used Mirror/UX for migrations from one array to another. Simple and can be done online with minimal impact.

As mentioned your listed commands do nothing to migrate the data unless the data has been migrated already on the back side using some kind of array data mover.

I always felt safter controlling this myself using the OS.

Best of luck.

[mohan singh]

Hi folks,

sorry for the confusion , data migration will be done by san utility (open replication /srdf/sancopy)from one box to another box. data I am talking about is few Tera transfer in short time.

After that I have to recover my application and database at server o/s level with new storage device.
I have hpux-11.11 using lvm.

appreciate your feed back.

REgards
Mohan

[mohan singh]

Hi
Procedure I have mentioned is to recover my vgs and file system on server level.

[Tim Nelson]

Then your steps are correct.

Note: I prefer to specify the devices when executing the vgimport so I know for sure I have the right ones.

vgscan can be used but it will tell you to vgimport the devices anyway.

[Geoff Wild]

Most people use a shovel to move the sand from one box to another...

JK!

Yes - your procedure is fine for a SAN based copy.

For step 4, use -s and drop the -p (no need to preview and that way you don't need step 8).

I would do a ll /dev/vg*/group > ~youruserid/vg.group.out
prior to the exports - to save the minor numbers of the group files as you need those for step 9 (0x000000 is vg00!!!!!).

12 - yes - you will need a fsck

Rgds...Geoff

[mohan singh]

Hi Tim, Geoff

Thanks for your comments, comming back to tim , I would rather like to import with /dev/dsk/cxtxdx, this is one of the safest approach , but there are many luns.

Does running vgscan make any sence before I import the vgs,
once I do vgexport my /etc/lvmtab will be have only vg00 info,Will vgscan populate all vg and corrosponging device to /etc/lvmtab . Any experience on this.

Thank
Regards
Mohan

[mohan singh]

Hi folks,

Thanks for your valuable comments.

Regards
Mohan