HAST and volume sizes

[Mikolaj Golub]

On Tue, 01 Mar 2011 18:18:26 -0600 Mark Felder wrote:

 MF> Hi all,

 MF> There doesn't seem to be any documentation on the effects of having
 MF> differing volume sizes for HAST. What happens if my MASTER is 1TB and
 MF> the  BACKUP is 1.5TB for example? Does it simply only care about the
 MF> first 1TB  of that volume because that's all the MASTER has? Would it
 MF> make things  easier when we replaced the MASTER's disk with a larger
 MF> disk? Or will it  just resync because HAST would be fresh (like I
 MF> expect).

In hastctl(8) for create command:

             -m mediasize   Size of the smaller provider used as backend stor-
                            age on both nodes.  This option can be omitted if
                            node providers have the same size on both sides.


So if you have disks of different sizes you have to specify the smallest size
on the resource creation.

It won't automagically resize when you replace the disk with larger one. The
way i see is (if you have A(1Tb), B(1.5Tb) and are replacing A with 1.5Tb):

1) B: start as primary, mount FS;
2) A: after replacing the disk recreate the resource, newfs, mount;
3) copy data form B:/mount to A:/mount manually;
4) B: change role to init, recreate device, switch to secondary.

-- 
Mikolaj Golub