[KLUG Hardware] Re: IDE RAID

[Bryan J. Smith]

On Fri, 2002-05-24 at 06:22, Adam Williams wrote:
> OK.  But why spend even $70 if the effective payoff is near zero. 

Let alone the fact that a 3Ware Escalade 6410 is only $99 and _really_
has 4 channels (not 2 channels and allows 4 drives to be used).

> I can,  so can RAID 5.  It requires a rather specific set of
> circumstances to occur.  A poorly configured RAID setup will usually
> simply fail to offer an increase in performance.

For production servers, I advocate a RAID-1 (or RAID-10) "system" volume
and a RAID-5 "data" volume.  Swap and temp don't work well on RAID-5.  I
do this on both my 8-channel 3Ware cards as well as for LVM.  In the
case of LVM for various OSes, it is just a heck of a lot easier to boot
a RAID-1 volume than a RAID-5 one.

> Because most consumer grade firmware sucks.  And you average IDE
> controller doesn't do jack to improve performance.

The average ATA controller is just a _bunch_of_wires_ connecting the ATA
device (with integrated drive electronics) to the CPU (PIO) and memory
(DMA).

> If spindle speed is ~identical then the drives are sort of synces, 
> they'll be "locked" at a fixed offset to each other.  With bigger
> buffers and faster spindles it really just matters less anyway.

Correct.

> It is pretty fixed.

Especially with today's fabbing.

-- Bryan

-- 
The US government could be 100x more effective, and 1/100th the
Constitutional worry, if it dictated its policy to Microsoft as
THE MAJOR CUSTOMER it is, and not THE REGULATOR it fails to be.
---------------------------------------------------------------
Bryan J. Smith, SmithConcepts, Inc.   mailto:b.j.smith@ieee.org
Engineers and IT Professionals     http://www.SmithConcepts.com