[linux-lvm] Raid 0+1

[Wayne Pascoe]

Hi all,

I am working on a project to evaluate LVM2 against Veritas Volume
Manager for a new Linux deployment. I am trying to get a Raid 0+1
solution working and I'm struggling.

So far, this is where I am:

1. I created 8GB partitions on 4 disks, sdb, sdc, sdd and sde, and set
their partition types to 8e with fdisk

2. I then ran vgscan, follwed by pvcreate /dev/sdb1, /dev/sdc1,
/dev/sdd1, /dev/sde1

3. Next, I created 2 volume groups as follows:
vgcreate StripedData1 /dev/sdb1 /dev/sdc1
vgcreate StripedData2 /dev/sdd1 /dev/sde1

4. Next, I created 2 volumes, one in each group as follows:
lvcreate -i 2 -I 64 -n Data1 -L 6G StripedData1
lvcreate -i 2 -I 64 -n Data2 -L 6G StripedData2
Now I have 2 striped volumes, but no redundancy. This is where I think
things start to go wrong.

5. I now create a raid device, /dev/md0 consisting of these two
volumes. I run mkraid on this, create a file system, and mount it on
/Data1. This all works fine, and I have a 6GB filesystem on /Data1

Now I need to be able to resize this whole solution, and I'm not sure
if the way I've built it caters for what I need to do...

I unmount /Data1 and use lvextend to extend the 2 volumes from 6GB to
7.5GB. This succeeds. Now even though both of the volumes that make up
/dev/md0 are extended, I cannot resize /dev/md0 using resize2fs
/dev/md0

Can anyone advise me how I can achieve what I'm looking for here ? I'm
guessing maybe I did things the wrong way around, but I can't find a
solution that will give me both striping and mirroring :(

Thanks in advance,


-- 
Wayne Pascoe