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/ _______________________________________________ bblisa mailing list [email protected] http://www.bblisa.org/mailman/listinfo/bblisa
