anaerin at gmail
Dec 29, 2005, 9:16 AM
Post #22 of 32
On 12/29/05, Brad DerManouelian <myth [at] dermanouelian> wrote:
Re: Samba 3 better than NFS 3 for recording over Ethernet
[In reply to]
> My point is that RAID 5 is *MUCH* slower than just about any other
> RAID config and you should expect your max speed to be half of your
> fastest drive. Put those U320's on RAID 0+1 and you'll likely double
> your speed (and half your recoverability). That being said, the
> original poster obviously hasn't got that kind of throughput and RAID
> 5 is cutting whatever he has in half.
Okay, with properly run hardware RAID, RAID 1 is the slowest (Data's
written to both drives at the speed of the slowest drive), RAID 5 is
next fastest (As the data spans the drives, so it's 1/3 faster than a
single drive or RAID 1), and RAID 0 is the very fastest (Data's
written to both drives simultaneously).
If you have the drives to spare (4 drives), and you don't mind
"Losing" half the capacity for the backup, then RAID 0+1 is the best
combination, giving high speed AND data redundancy (50% capacity, 200%
If you don't have the drives (3 drives), or you wish to get more
capacity from the drives you have, then RAID 5 is best, as it gives
you 66% of the capacity of the drives and 133% of the performance.
If you have only 2 drives, you can opt to use them as RAID 1 (Which
will give you 50% capacity and 100% performance) or RAID 0 (Which
gives you 100% capacity (And 0% redundancy), and 200% performance).
This is all assuming you're using hardware RAID, which is not reliant
on CPU overheads or anything like that. Software RAID changes this, as
it uses the CPU and the regular IDE controller, but can't (generally)
write to multiple drives simultaneously.
Robert "Anaerin" Johnston
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