mirror and break mirror OS:11.23 model:ia64

[masood bt]

Hello.

Have a server with two disks.
mirrored.

i have a third disk in hand..need to mirror this with the existing disk in the server and use this third disk to boot some other server..somewhere else.

The steps I think appropriate are:

(1)identify the disk (one of the two disks) to be removed from server

(2)break the mirror (and do not take it out)

(3)reboot the server with second disk

(4)if it works, reboot the server with first disk

(5)now remove the second disk out from the server

(3)Insert the the third disk in hand, now into the server.

(4)mirror the third disk with the existing disk in the server

(5)reboot the server with the third disk ( to test if it has got mirrored properly)

if it works,

(6)reboot the server with original disk

(7)break the mirror between original disk and third disk

(8)do not remove the third disk now...but

(9)Reboot the server with third disk(to test if it still works after breaking the mirror)

if it works,

(10)reboot the server with original first disk

(11)remove the third disk from the server

(11) insert the original second disk into the server and re mirror(sync)

Are the above steps okay?

I have other questions like,
for breaking the mirror
i do #vgreduce ....
#lvreduce -m 0 .....

is this correct?
thx

[Johnson Punniyalingam]

>>Are the above steps okay?<<

Would recommend to check below link, above (Plan) looks Good.

http://docs.hp.com/en/5991-1236/When_Good_Disks_Go_Bad.pdf


>>I have other questions like,
for breaking the mirror
i do #vgreduce ....
#lvreduce -m 0 .....<<<

its other way around

# lvreduce -m 0 /dev/vgname/lvname /dev/dsk/cxtxdx
# vgreduce /dev/vgname /dev/dsk/cxtxdx

man lvreduce
man vgreduce

[Steven E. Protter]

Shalom,

PSB

Pretty well thought out plan:

The steps I think appropriate are:

(1)identify the disk (one of the two disks) to be removed from server
vgdisplay -v lvdisplay -v pvdisplay -v


(2)break the mirror (and do not take it out)

# will work, look at lvsplit command

(3)reboot the server with second disk

May not be needed for hot swap disk. insf -C disk insf -e


(4)if it works, reboot the server with first disk

(5)now remove the second disk out from the server

(3)Insert the the third disk in hand, now into the server.

(4)mirror the third disk with the existing disk in the server

(5)reboot the server with the third disk ( to test if it has got mirrored properly)

if it works,

(6)reboot the server with original disk

(7)break the mirror between original disk and third disk

(8)do not remove the third disk now...but

(9)Reboot the server with third disk(to test if it still works after breaking the mirror)

if it works,

(10)reboot the server with original first disk

(11)remove the third disk from the server

(11) insert the original second disk into the server and re mirror(sync)


SEP

[Torsten.]

Break the mirror usually means delete data from disk.

So shut down server, take out the disk.
Boot the server, insert new disk and sync the mirror (follow the steps from the PDF above).

Now you have a copy in your hands and a mirrored pair in the server.

[masood bt]

Yes, I am actually worried about losing the data while doing lvreduce and vgreduce.

So, I will drop the idea of breaking the mirror by using lvreduce/vgreduce.

Now I need to consider two other ways.

(A)
above planned steps with lvsplit(instead of lvreduce)
(I need to have the lvsplit commands in hand please can somebody help me out here)

or

(B)
(1)two disks in server, third disk in hand.
(2)shutdown the server,remove one disk. insert third disk.
(3)boot the server
(4)mirror..third disk also now has same data as the original disk
(5)shutdown the server.remove third disk..insert the original(second) disk..now the server has it own original two disks still in mirrored state
(6)now i cam use the third disk to use it in some other server somewhere else.

can i use the third disk mirrored in this way in some other server to boot?..without any problems?

[Torsten.]

Procedure B!

But why inserting the old disk again? This step is not needed.


The new server booted from this disk (same server model???) will have the same name, same IP!

Consider to boot into single user mode, use "set_parms initial"!

[masood bt]

inserting the second disk (old disk) because the server should be left in its original state...with its two mirrored disks intact.

I will use this newly mirrored disk to boot some other server(same model) somewhere else.

do i need to do any vgexport/import stuff once i take this third disk to the other server?

[Torsten.]

It depends - do you want to vgimport disks?

The best method to "clone" a server is ignite, but this procedure may work too.

If you insert the "cloned" disk into the same slot, you don't need vgexport/vgimport this disk.

[masood bt]

When I get my third disk mirrored... when i remove it from the server...and insert it in some other server... the hardware path of the disk changes..isnt it?

so..i am thinking...may be i need to boot the second server in maintenance mode/export vg00 and import is again

any comments?

[Torsten.]

If the position in the new (same model) server is the same, the path will be the same.

[masood bt]

fyi... the existing two disks in the server are working fine.

So, our conclusion is....

1)two disks in server, third disk in hand.
(2)shutdown the server,remove one disk. insert third disk.
(3)boot the server
(4)mirror..third disk also now has same data as the original disk
(5)shutdown the server.remove third disk..insert the original(second) disk..now the server has it own original two disks still in mirrored state
(6)now i cam use the third disk to use it in some other server somewhere else.


I am also thinking that..the server..if it has a third slot..i will not remove any disk out..i will insert the disk in the third slot, lvextend -m 2
then, i will shutdown the server, remove the third disk..and use it to boot the second server

[Torsten.]

Until now I assumed you don't have a free slot.

Yes, you can do that. Your server will finally complain about a missing disk, consider to use vgreduce -f to clean this out.

[masood bt]

now i can confirm, it has altogether four slots.

>i will shutdown the server
>i will insert this thrid disk.
>mirror it.
>shutdown the server.
>remove the third disk.

( i am thus by passing mirror break / lvsplit)

i hope this works, because... this third disk is to be used to boot and to be used in a server in some other city....and if it doesnt work... lot of efforts go waste

[Torsten.]

With 11.23 you may even think about using DRD (dynamic root disk).

[masood bt]

thx..reading abt DRD now :-)