Tell me more ×  If I happen to have two external hard drives,
one 1.5TB and then other 2TB, and use Disk Utility to mirror the
two drives, will there be any problem?  Can it be mirroring just
for the 1.5TB portion, while the remaining 500GB is for storing
un-mirrored files? (but will Mac OS X always try to mirror those
files and try to copy into the 1.5TB drive?)  (will it be the
same if the two drives are 2TB and 3TB, or if the drives are
different brands, so the capacity might differ slightly?)
share|improve this question add comment  1 Answer  up vote 1
down vote accepted  In this situation, I recommend using disk
utility to partition the larger drive such that one partition
matches the size of the smaller drive. Then setup the partitions
of the same size as a RAID1. You will end up with a mirrored
partition of 1.5TB and another un-mirrored partition of 0.5TB
based on your first example.  Same thing will work for a 2TB +
3TB drive, but the mirrored/un-mirrored partitions will be 2TB
and 1TB, respectively.