Mis-matched disks RAID 1

Mis-matched disks RAID 1

[AndyLiebman]

Can somebody tell me what I have to do to make a RAID 1 array with 
mis-matched disks (1 is 200 GB, one is 160 GB)? 

I am assuming I have to make 2 partitions on the 200 GB drive -- one exactly 
the same size as the 160 GB drive, one with whatever is left. Is that true? 
And is there an easy way to make the big partition EXACTLY the same as the size 
of the 160 GB drive? (When I look at the 160 GB drive with fdisk, I see a size 
that's a certain number of sectors (?)  xxxxxxxxxx+  with a plus sign at the 
end. )

My situation is the following: 
I have 5 Maxtor 160 GB firewire drives and 1 Maxtor 200 GB firewire drive. I 
want to make 3 pairs of RAID 1 arrays and then stripe them as a single RAID 0 
array. 

I have already done essentially the same thing with 6 200 GB drives and it 
works great. But now for the second set of drives I have one that's bigger than 
the rest. I want to be sure I don't have any problems. 

Good advice appreciated. Thanks in advance. 

Re: Mis-matched disks RAID 1

[Neil Brown]

On Thursday November 20, AndyLiebman@aol.com wrote:
> Can somebody tell me what I have to do to make a RAID 1 array with 
> mis-matched disks (1 is 200 GB, one is 160 GB)? 

"Just do it!" :-)

> 
> I am assuming I have to make 2 partitions on the 200 GB drive -- one exactly 
> the same size as the 160 GB drive, one with whatever is left. Is that true? 
> And is there an easy way to make the big partition EXACTLY the same as the size 
> of the 160 GB drive? (When I look at the 160 GB drive with fdisk, I see a size 
> that's a certain number of sectors (?)  xxxxxxxxxx+  with a plus sign at the 
> end. )

They do not have to be exactly the same size.  The size of the raid1
array will be slightly less than (to allow for metadata) the size of
the smallest drive.

So, partitions the 160GB drive as a single 160GB partition, and
partition the 200GB drive as a 160GB and a 40GB, but don't be stressed
about getting the sizes precise.
Then raid1 the two 160GB partitions together, and you get a bunus 40GB
non-RAID partition to play with.

NeilBrown