[CentOS] Growing HW RAID arrays, Online

Sat Feb 22 01:06:55 UTC 2014
Billy Crook <bcrook at riskanalytics.com>

On Fri, Feb 21, 2014 at 6:50 PM, Phoenix, Merka <merka.phoenix at hp.com> wrote:
>>> add disks to an LSI raid array periodically to increase the amount of available space for business needs
>>> sdc1 is a PV in a VG that holds production data and must not become unavailable at any time
>>> How do we grow sdc1, online?
> If you are using the Logical Volume Manager (LVM ) on Linux, you should not have to grow the PV each time.
> Instead, carve Logical Units (LUNs) out of the RAID array and present them to the operating system as disk devices that can be initialized as physical volumes (PVs).

My raid controller doesn't permit adding luns to an exiating array
that has a single lun.  It requires it to bave originated as a
multiple-lun array.
Even if it did permit this, I need the number of PVs to stay fairly
consistent for logistical reasons.  I cannot have a new one come into
existance every time I grow the array.

> While you can resize the H/W RAID "online", and add/remove PVs to a VG "online", you still need to unmount a filesystem before resizing both the LV and the corresponding filesystem that was created on the LV. Attempting to resize a filesystem that is mounted and actively being used is just asking for data corruption.

Not true, most filesystems support online grow/expansion.  The ones
I'm using do, and it works fine, and is fairly quick.

I am aware of how lvm, and filesystems work.  I don't need help with
those.  I'm asking one thing: how to get the kernel to notice that a
partition has grown.