Re: With 4 disks should I go for RAID 5 or RAID 10

Bill Moran wrote:
>
>> What do you mean "heard of"? Which raid system do you know of that reads
>> all drives for RAID 1?
>>
>
> I'm fairly sure that FreeBSD's GEOM does. Of course, it couldn't be doing
> consistency checking at that point.
>
According to this:

http://www.freebsd.org/cgi/man.cgi?query=gmirror&apropos=0&sektion=8&manpath=FreeBSD+6-current&format=html

There is a -b (balance) option that seems pretty clear that it does not
read from all drives if it does not have to:

Create a mirror.
The order of components is important,
because a component's priority is based on its position
(starting from 0). The component with the biggest priority
is used by the prefer balance algorithm and is also used as a
master component when resynchronization is needed, e.g. after
a power failure when the device was open for writing.

Additional options include:

*-b* /balance/ Specifies balance algorithm to use, one of:

*load* Read from the component with the
lowest load.

*prefer* Read from the component with the
biggest priority.

*round-robin* Use round-robin algorithm when
choosing component to read.

*split* Split read requests, which are big-
ger than or equal to slice size on N
pieces, where N is the number of
active components. This is the
default balance algorithm.

Cheers,
mark

--
Mark Mielke <mark(at)mielke(dot)cc>