On Monday 11 December 2006 07:57, Tim Post wrote: > My question is , what is the correct way to calculate the physical > extent size of a volume group relative to the size of the array?
From man vgcreate: If the volume group metadata uses lvm1 format, extents can vary in size from 8KB to 16GB and there is a limit of 65534 extents in each logical volume. The default of 4 MB leads to a maximum logical volume size of around 256GB. If the volume group metadata uses lvm2 format those restrictions do not apply, but having a large number of extents will slow down the tools but have no impact on I/O performance to the log‐ ical volume. The smallest PE is 1KB. It's a tradeoff. If you use smaller extents you may not be able to grow beyond a certain size in LVM1 and even if you convert to LVM2 some tools (but not normal usage) may be slow. OTOH, if you use larger extents you waste some space if you have lots of small logical volumes. FWIW, I have always used 32MB extents. --Mike Bird
