 Adding meta to meta LUN will create performance issue. I'd make a correction here.  "Adding meta to meta LUN *can* create a performance issue"  It's entirely dependent on how the meta components are laid out.  Meta's can also improve performance if done correctly.  There is one very important basic rule to follow with Meta's to avoid most of the performance issues..  NEVER stripe on the same physical disks, only Concatenate when Meta components are sharing disks.  Creating a Meta where multiple striped components are sharing the same disks will cause head thrashing and higher response times.  The same rule applies at the host level as well..  Don't allow LVM (VxVM, ASM, etc) striping across multiple LUNs coming from the same RAID Group.  If you have components that are created on separate RAID Groups, then Stripe them.  This will improve overall performance of the LUN due to the larger number of disks supporting the meta compared with a single LUN in one RG.  ie: A 200GB striped Meta across 3 x 4+1R5 RAID Groups will perform better than a single 200GB LUN in a single 4+1R5 RAID Group.  A 200GB concatenated Meta in a single RAID Group will perform roughly the same as a 100GB normal LUN in the same RAID Group.  If you just need to increase capacity and want to use free space that is in the same RAID Group as the existing LUN, then concatenate.  Of course, if you have the luxury of free space elsewhere in the array where you can create a new larger LUN, a LUN Migration to the new larger LUN would be a good idea.
My Array: NS-960 Flare 30  I know I can concatenate a LUN to a MetaLUN.  Can I concatenate a MetaLUN with another MetaLUN?  If so, how?
MetaLUN