On Nov 16, 2007 2:07 PM, Ben Barrett <[EMAIL PROTECTED]> wrote:

> Right on, thanks Quentin -- this better-defined "fakeraid" is much
> worse than soft-raid in many cases,


I'd amend this to say _all_ cases. <overbroad inflammatory statment>Fakeraid
is a technological abomination, created by marketing departments and
unchecked capitalistic market forces.</ois>

<snip>

> modern CPU's are *plenty* fast enough to
> maintain throughput using simple soft-raid.
>

 Anecdotal data point: My home server is running on a 1Ghz Via C3 processor.
I have a 3+1 software Raid 5 array in it. The processor is fast enough to
saturate a 100MB ethernet connection copying data off the drives over NFS,
but not over Gb. When I copy stuff via Gb, throughput is very bursty, but
probably averages out to about  400-500Mb / sec


> I have not seen the most recent benchmarks or fully examined the
> latest HA (high-avail) compromises, but SCSI is still much better that
> SATA (bye, PATA) for high-volume multithreaded uses needed for many
> email, DB, web, and other servers.


I have been tracking this stuff pretty closely, so I'll throw another few
cents based on my experiences. I've found that SCSI's primary advantage over
SATA comes from access time and IOPs (I/O operations per second). Unless you
have a workload that specifically requires it, SCSI is generally not worth
the money, even in "important" servers for business. I've found that it ends
up being more economical to have several "cheap" SATA-based servers than one
big SCSI(or SAS) based server. Of course, there are cases where this is not
true; per server license costs can influence this as well as the
clusterability of whatever service or application you are running. I've
gotten to the point though that I tend to "cheap cluster" by default, and
only "big iron" when there are specific factors that make cheap cluster not
work.

That being said, SCSI's edge over SATA isn't quite as thin as it seems on
paper, where even in areas like seek time and IOPs some SATA drives are
challenging SCSI. There are the intangibles. The firmware on SCSI drives
tends to be a little more conservative, and the drives tend to be tested to
somewhat higher standards. These two items combined lead to more reliable
drives. Another somewhat intangible advantage is that the hardware that
surrounds and supports SCSI drives tends to be higher quality than that
which is built to support SATA. This leads to an overall better experience.
All in all, SCSI still has quite a few advantages over SATA, but the simple
"it's just always better" is no longer true.


> If this isn't making any sense to you, I'd like to simply propose the
> breaking and recovery of a raid array at a public function like the
> eugene celebration.  I would be happy to bring down a sledgehammer and
> provide the single drive which we'll rip out and destroy (to great
> effect but in a contained manner).  After that hooplah, a simple
> showing of the recovery:  rebuilding in progress, etc, and some
> well-planted statements from the audience about whether this reliable
> and well-supported, free technology could help our government's
> accountability or something :)
>

This would be hilarious. I too have some donatable drives...

-- 
-Regards-

-Quentin Hartman-
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