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[Rushank]

Hello,

Four of my disks shows constantly very high i/o and at times reports disk bottleneck. Thes e disk are not on FC.

I've identified the disks and planing to add new FC disks modules to the system.

Once I add these disks how do i copy the data to new disks. These are production data (Oracle).
I am not expanding the logical volume but transfering entire data to new disks within the system instead.
What would be the best method to do this.
like creating PV, VG and logical volume etc...
I would like to use existing vg name, lv name and mount points for the new disks.

2. How many disks I can attach for a daisy chain

Thanks in advance..

[linuxfan]

Hi,


One of the ways with minimum downtime would be the following,

pvcreate the new disks
vgextend the existing VG to the new disks
pvmove the existing lvs from current disks to the new disks

All this can be done oneline.

Once the data has been moved to the new disks, vgreduce the old disks from the VG.
You might want to check the man pages for (vgextend and pvmove)

But before you do this, make sure you have a backup of your databases.

-HTH
Ramesh

[Sanjay_6]

Hi,

To move the data from one disk to another, you have to proceed like this.

Connect the disk to the system, do a pvcreate on the disk, do vgextend to include the disk in the VG, do pvmove old disk --> new disk. the data is now on the new disk. you may have to do a vgreduce to remove the old disk from the VG and then disconnect the old disk from the system.

Hope this helps.

Thanks

[Sridhar Bhaskarla]

Rushank,

I concur with Ramesh and Sanjay. If you are too cautious ( I do for my management) about the data, you can mirror the existing logical volumes onto the FC60 and then break the mirror.

1) Add the new LUN from FC 60 to the volume group
2) Use the lvextend -m 1 /dev/vg??/lvol? /dev/dsk/cxtydz (new disk). Replace ?s and x,y,z with your settings.
3) Do an lvsplit, fsck and mount the backup copy (bydefault it will be lvol??b). Verify if the database is fine. Then remove the original logical volume and reduce the old PV from the volume group.

pvmove is also safe. You can go with it if you don't want the lengthy procedure.

-Sridhar

[Santosh Nair_1]

The one big concern is that the new disks you're adding shouldn't be bigger than the disk in the VGs. For example if you're VG consists of 2 x 4GB disks, then the disks should also be 4GB otherwise you'll be wasting space as only 4GB of the new disk will be accessable from the VG.

If this is not a concern, then you should be able to pvcreate the new disk(s) and vgextend the volume group to include the new disks. Then use pvmove to move the data from the old disks to the new and finally use vgreduce to get rid of the old disks from the VG.

-Santosh