[BBLISA] Recommendation for NAS appliance?

[Tom Metro]

Jeff Wasilko wrote:
> EMC's Celerra NAS devices have a fully redundant back-end Clariion
> array. This has the typical config of dual storage processors that can
> take over for each other connected to dual-ported trays of disk.

What kind of interface between the trays and the processors? FC?

With high-end storage moving to SATA, I've been wondering how they pull 
off redundancy. Not as simple as putting two controllers on one SCSI 
bus. I'm guessing they're using custom silicon.

I wonder how one might emulate that level of fault tolerance using 
commodity hardware, short of say putting an AoE[1] interface[2] on each 
disk and chaining them together via Ethernet. Looks like a Taiwanese 
company makes a 4-bay drive tower with AoE interface[3]. Two attached 
through a switch to a pair of hosts would be close.

A device that could switch between two multi-lane SATA ports would do 
it. Other people have been musing[4] about the same idea. But that's 
probably back to custom silicon. It doesn't seem likely that one of the 
SATA multiplexer chips (like what is found in this hub[4]) could be 
coerced to do this. And technically you'd be back to a single point of 
failure, even if a small footprint.

I see 3ware has RAID controllers with what they call "StorSwitch" 
technology that relates to this, but no mention of it being able to 
support two controllers on the bus.

Back on topic, I see Coraid (inventor of AoE) has a fault tolerant NAS 
gateway appliance[5] to go with their AoE racks. Anyone used AoE? It 
seemed to show a lot of promise, but has been slow to gain adoption.

  -Tom

1. http://www.storagesearch.com/aoe.html
2. 
http://www.alibaba.com/product-free/252853040/AoE_enabler_internal_product.html
3. 
http://www.alibaba.com/product-free/108547397/3_5_inch_4Bay_SATA_RAID_over_Ethernet_Desktop_OEM_Model.html
4. 
http://www.tomshardware.com/forum/198419-32-esata-switcher-possible#t1787417
5. http://www.cooldrives.com/sahub5muussi.html
6. http://www.2northlan.com/2008/06/10/cln21-ft/

-- 
Tom Metro
Venture Logic, Newton, MA, USA
"Enterprise solutions through open source."
Professional Profile: http://tmetro.venturelogic.com/