"Bob Meyers" <oregonbob2000 at yahoo.com> wrote in message
news:6uWdnbc2GshuiozcRVn-uA@centurytel.net...
>
> "Stuart J. Browne" <stuart@promed.com.au> wrote in message
> news:41104d05@dnews.tpgi.com.au...
> >
> > However, your original emssage said "2 HD mirror the other 2 HD's",
which
> > sounds more like RAID 1, rather than RAID 5.
>
> Yeh, that does sound like a RAID1.
>
> Pardon if this is topic drift, but I keep seeing posts in this newsgroup
> (over the years) about people running RAID5 on 4 drives. AFAIK, RAID5 uses
> THREE drives and any of the three drives can fail without problems. The
> remaining two drives can operate and rebuild data on the failed drive when
> it is replaced. Therefore, isn't it a total waste to run 4 drives in RAID5
> configuration? Isn't the 4th drive a "spare to the built-in spare"?

RAID 5 requires a MINIMUM of three drives. I have seen up to a ten drive
RAID
5 (there are some that are probably larger) with three hot spares standing
by.

Adding more than three HD's to a RAID 5 just adds more storage space.

I currently run a four drive RAID 5 with two hot spares. At the time I
wanted more
storage space for a single drive (Four 18GB drives acting is 54GB, obviously
separated into multiple partitions).

moncho.