gmirror, gpart and MBR vs GPT in the Handbook
Warren Block
wblock at wonkity.com
Mon Dec 2 15:56:15 UTC 2013
On Mon, 2 Dec 2013, Julien Cigar wrote:
> If you want to use GPT with gmirror you may want to mirror each
> partition instead of the whole disk.
>
> For example on my box I have the following: https://dpaste.de/Rb3S
There are a couple of potential problems with that. The big one is when
a disk fails and is replaced. If you're not careful, the rebuild of all
those mirrored partitions will start at the same time. Head contention
will bring that to a near-standstill. It also puts a heavy load on the
drive that still works. Hopefully it is not the same model and age as
the one that failed, or its "warranty timer" may also be close to
expiring.
A less-serious problem is that only the partitions are mirrored. That
leaves out metadata like the partition tables and bootcode, but those
typically do not change very often and might not be a problem. The
admin has to remember to manually install such things on a new
replacement disk, though.
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