Replace 2 disks 9G with mirror to 2 disks 18G

[yaron daniel]

Hello All

I have a cluster with 2 K570 servers , hpux 10.20 + MCSG version A.10.20. The package is ORACLE db and it contains 2 disk arrays:
HA Factory Racked Storage Enclosure A3312AZ
each one with 8 disks SEAGATE ST39173WC (9G)
and each disk is lvol and have a mirror in the second array. all the disks belong to one volume-group.
My problem: i need to replace 2 disks (1 lvol - 9G lv-size) to bigger disks - 2 disks - 18G.
How can it be done with the less downtime of the system ???

[Jeff Schussele · Accepted solution]

Hi yaron,

This will probably be a problem because unless you overrode the defaults when you created the LVs, you will not be able to just add the 18GB disks to the LV because the Max PE/PV value will be too low to allow the 18GB disks to use their full value.
I see the necessity of downing the pkg & recreating the LV from scratch in your future.
So get a change window, backup the LV (twice) & recreate it & restore it. At least you can back it up outside the window...

Rgds,
Jeff

[Steven E. Protter]

If you have mirror/ux its easy

put in disk
ioscan
insf -e

lvextend -m 1 /lvol_name /dev/dsk/c#t#d# of new disk

remove old disk replace.

Repeat operation.

You can actually do it if you are careful witht he database up, assuming the new disk is hot swapable.

Safer though is down the database and system, mirror after reboot.

Boot again, get rid if original disks.

If you already are funning Raid 5 on this array you don't even need to do mirror/ux

SEP

[yaron daniel]

Hi
The 2 arrays are full, i need to break the mirror of the lvol and then replace to the new 18G disk (call disk1) then copy the data form the Source 9G disk, and after that remove the Source disk and add the new 18G disk (call disk2) for copy from disk1 to disk2. after that remove disk1 and make a mirror to disk2.
IS THAT MAKE SENSE ???

[Jeff Schussele]

As stated earlier - do a vgdisplay -v & check the max PE/PV value & multiply that by the PE size value & I think you'll see what I'm saying.

Rgds,
Jeff

[yaron daniel]

Hi
I saw that the Max PE per PV is 2170.
That means i need to recreate the pkg.
Is that the only way ???
Yaron

[Patrick Wallek]

You don't need to recreate the MC/SG package, you just need to recreate the VG. With your Max PE per PV at 2170, your PE Size is probably 4, so the max disk size you can use in that VG is 8680 MB. You *could* add in the 18GB disks, *but* you would only be able to address 8680MB of the 18GB.

This is a good reason to make it a habit of increasing the MAX PE per PV on any VG you create. I will generall use a faily large value, somewhere between 5000 and 10000 depending on the current disk size, and a PE Size of 8 or 16 MB.

Good luck.

[yaron daniel]

Hi
I thinking of this plan:
1) break the mirror at the lvol that i want to replace his disks.
2) remove one of the disks, and place the new one 18G.
3) create new vg to the new disk.
4) copy the data from the old disk to the new disk.
5) mount the new disk with the original mount-point.
6) check the oracle.
7) update the MCSG config files and dist
8) up MCSG system.

What i need to know, does it is metter to oracle if one lvol will be with PE size 8
and another lvol will be with PE size4 ???

[Robert-Jan Goossens]

No not at all.

Regards,
Robert-Jan

Ps, on extra step remirror your new vg !

[yaron daniel]

Sure - 10x

Yaron