Re: Raid 5 with 4 drives
- From: "Daniel Crichton" <msnews@xxxxxxxxxxxxxxxx>
- Date: Wed, 5 Mar 2008 10:35:31 -0000
PaulMaudib wrote on Tue, 04 Mar 2008 18:11:57 -0600:
On Tue, 4 Mar 2008 16:50:51 -0500, "Adelxt" <sales@xxxxxxxxxx> wrote:
Hi,
I'm presently running a raid 5 with 3 drives. If two of the three
drives fail, then I would have to re-install the OS and restore from
backup. If I use 4 drives for a Raid 5, would I not have to restore
the OS until three of the 4 drives failed? Would it be 4 of 5 drives
if I chose to have a Raid 5 using 5 drives.
What I'm thinking is that the possibilities of more then two drives
failing at once is slim but if that happens I could still keep my OS
intact if I used a Raid 5 of 4 drives or more.
Thanks
Steve
If you are using RAID 5 on three drives and lose 1, you've lost the
entire thing. RAID 5 requires MINIMUM 3 drives to operate. Lose on
and you've lost your fault tolerance. For fault tolerance, you need to
add at least one more drive.
If you lose 1 drive in RAID 5 you do not lose the entire array - the other
drives hold the parity information to rebuild the failed drive. I've had
drive failures in RAID 5 systems with 3 drives and recovered them by
swapping the failed drive for a new one and rebuilding, just like in RAID 5
setups with more drives.
I'd avoid using systems with RAID 5 with 3 drives though - apart from the
couple I have here for development use, the other serves all have RAID 5
with 5 drives + 1 hotspare, or RAID 10 across 2 arrays of 3 or more drives
per array.
--
Dan
.
- References:
- Raid 5 with 4 drives
- From: Adelxt
- Re: Raid 5 with 4 drives
- From: PaulMaudib
- Raid 5 with 4 drives
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