[linux-lvm] Software raid on top of lvm logical volume

[Markus Baertschi]

Michael T. Babcock wrote:

>
> I've thought about this numerous times -- there is the distinct 
> resizing advantage.  Namely, if I create a software RAID partition, I 
> can't resize it afterward without destroying it.  I have for example, 
> on occasion, had three disks set up where 1/3 of each was devoted to a 
> RAID-0 very fast striping set for data transfers that had to be fast 
> but if they were lost it wasn't critical, and 2/3 was set up as RAID-5 
> for reliability of another set of data.
>
> I understand this may not be optimal in some situations, but some of 
> us don't have thousands of dollars for SCSI HW RAID controllers.

You can make life easier by creating several raid arrays on the same 
disks and tie them together with LVM.
For example split your three 160GB drives into 4 partitions each and 
create a raid over the three disks.

sda -> sda1+sda2+sda3+sda4, etc.
md0 = sda1+sdb1+sdc1, md1=sda2+sdb2+sdc2, etc.

Markus

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