[Pc_Support] Re: eSATA RAID-1, putting the "IOP" outside the box -- WAS: Synology DS-106 w/FTPS (explicit) access

[Bryan J. Smith]

On Tue, 2006-08-22 at 23:10 -0400, Damien McKenna wrote:
> I'm also looking at the *Thecus N2050 series which are eSATA drives
> with built-in RAID 0 and 1, those would be pretty darn wonderful for
> easy & reliable external expansion on miniature systems (think: Mac
> Mini).*

On Tue, 2006-08-22 at 23:13 -0400, Jason Boxman wrote:
> Interesting.  At work we just USB2 two external enclosures and RAID 1
> that on the Mac Minis.  Seems to work well enough.

Actually, eSATA RAID-1 would be nice.  Here's why ...

1.  Most of these eSATA devices have FreeScale or XScale 200-400MHz RISC
microcontrollers aka I/O Processors (IOP) -- designed in-line I/O
Processing with near-0 wait state operations

2.  No NAS/general OS overhead on the processor, just pushing I/O data
_in-line_ -- which is what the IOPs are designed for, and not all that
additional overhead like a cheap NAS which only detract from near-0 wait
state I/O operations

3.  You don't need much DRAM, firmware, etc... to do this when you do
only I/O Processing, further saving on embedded costs

4.  SATA is a "direct, dumb block" protocol, unlike USB, TCP/IP or even
Ethernet for that matter (sorry, ATA over Ethernet is _not_ viable --
don't get me started ;-).  It's basically SAS (Serial Attached SCSI)
without the flexibility, but also less overhead too.

If you read up on the few reviews, the performance isn't as good as a
traditional 3Ware ASIC+SRAM card, but it's still a bit better than most
NAS and USB devices too ...
  http://www.hexus.net/content/item.php?item=4817  
  http://www.trustedreviews.com/article.aspx?art=3279  

They are getting ~50MBps RAID-1, ~80MBps RAID-0, using commodity SATA
disks.  Far from best, but also much, much better than other options.
And I'd personally like to see how it fares against Linux's MD
(software) RAID-1 -- I think most would be surprised.

Now if the prices came down to $100, I'd buy one.  I can only put two
(2) SATA drives in my MicroATX cube (assming I'm using the 2x5.25" and
1x3.5" external) and I'd like to have additional, but RAID-1, storage.


-- 
Bryan J. Smith          Professional, technical annoyance
mailto:b.j.smith at ieee.org    http://thebs413.blogspot.com
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