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Date:      Thu, 14 Feb 2002 00:54:04 -0500
From:      <sbernard@gmu.edu>
To:        freebsd-stable@FreeBSD.ORG
Subject:   Re: Best ATA RAID controller 
Message-ID:  <ea2c62ea605f.ea605fea2c62@gmu.edu>

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Here's what I've been able to find:

The 6000 series is in "end of life" except for the Escalade 6410. In my 
somewhat limited search I found the best price at Hyper Microsystems, 
http://www.hypermicro.com/store/index.htm. Their price for a 6410 with 
cables, etc. is $119 US. For those who aren't familiar, this is a 4-
channel ATA-66 RAID controller. It supports up to 8 drives with slaves. 
I called 3Ware and they informed me that the maximum supported disk 
drive size is 160GB. That is per drive, not total. So you can have a 
maximum capacity of 1.28TB of storage, using RAID 0. Not too shabby, 
eh? Even my collection of MP3 live sets isn't _that_ big ;)

The benchmarks that I could find indicate that minimal performance gain 
is achieved by going to the Escalade 7xxx series, unless you need RAID 
5. In that case, the 7450 is very much on top. Also, using a 64-bit PCI 
slot provides relatively minimal gain vs. 32-bit due to the limitations 
of ATA disks and the host system. The authors of almost every benchmark 
or review of these cards, and ATA RAID in general, started off by 
heralding the 3Ware controllers and referred to the "anticipation" 
experienced while they were waiting for the various controllers because 
of their high expectations and past experiences. That's a definite plus 
in my book.

I don't have the independent benchmark numbers offhand but, 3Ware 
claims something like 75MB/s write speeds for their cards when using 
RAID 0. I think their numbers are for a 4 drive array. To put this in 
networking terms, a fully saturated OC3, 155Mb/s, is just over 19MB/s.  
Of course, you don't really get 155Mb/s due to various factors, just as 
a T1 won't really give you a full 1.54Mb/s. This is important for those 
considering using one of these controllers on a networked server. In 
other words, these controllers will take most any network load 
experienced by business class file servers. A gigabit link on the 
otherhand has a theorectical throughput of 125MB/s so be careful in 
those environments.

FWIW, those who have expressed interest in RAID 5 should note that 
using RAID 5 arrays of over 4 or 5 disks will begin to incure 
significant overhead and greatly reduce performance. If you are running 
a database server or the like with this setup you may want to consider 
a reconfiguration. Block size and other filesystem settings can cause 
significant performance gains or losses. Tune your db and RAID array to 
find the optimal setting for your environment. The defaults are not the 
best for every situation.

I might have forgotten something but, if I remember, I'll get back.

Regards,

Steve

p.s. Please don't buy up all of the 6410s. I need two and haven't made 
my purchase yet ;)


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