So if you've got data spread around those PPs, would you just like to lose it? The OS is moving the data to PPs that will survive the reduction. It will be doing this for every copy of an affected LP, so with mirrors, you've just doubled/tripled up.

Yes, the IO for the filesystem will lock. If you were working to keep space clear on certain PPs, how would you like it if another process looked and said "Oh lovely, a nice contiguous area of free disk to write in."

From your iostat you need to read the display clearly. Disk hdiskpower9 is reading. Writes are to hdiskpower0.


I hope that this helps your understanding, but organise downtime to take such actions as they are more complex then growing a filesystem.



Robin