Raid setup

[Boozeman]

Dear all,

I am going to buy a new server for my compny but I am undecided on what
RAID setup to order.

Currently we have 3 disks in a raid 5 array, the salesman suggests 4
disks in 2 raid 1 arrays (one disk for OS + 1 disk for database) which
he says will be safer.

I was thinking on a 6 disk raid 5 + 1 setup.

Any suggestions?

thanks,

Fred

 

[Geir Klemetsen]

Dear all,

I am going to buy a new server for my compny but I am undecided on what
RAID setup to order.

Currently we have 3 disks in a raid 5 array, the salesman suggests 4
disks in 2 raid 1 arrays (one disk for OS + 1 disk for database) which
he says will be safer.

I was thinking on a 6 disk raid 5 + 1 setup.

I'm agree with you. If one of the five disk crash, you'll be able to restore
the raid5 array, using one more disc.

An 1+0 array will also be posible to restore, even if two of the discs goes
down, you'll have about 50% chance to restore the volume.
====[Hdd1]====[Hdd2] Stripe set 1
====[Hdd3]====[Hdd4] Stripe set 2
Those two striped sets is mirrored -> Set2 contains a true copy of Set1.

As you can see, if Hdd1 and Hdd3 both fails (less likely), it'll not be able
to rescue the data (unless you send it to an hdd recowery company =
expensive deluxe)

Buy at least one more disk than you are planing using in raid-volume. You'll
need it badly if one of the disks in the raid-volume fails. I'll beleive
it's ok to use another type disc as replacement, but it's recomended that
all disks in the volume is similar.