Held a Storage Field Day briefing yesterday with Coraid, the creators of EtherDrive an all Ethernet SAN storage system.
The advantages of EtherDrive are significant. Not the least of which is that it is very cheap storage. It scales independently as each storage server/node is a separate storage system. Also it’s very easy to set up as each storage drive has it’s own MAC address.
I suppose the downside is that it uses an internal storage access protocol to supply access across the Ethernet. This requires a special host device driver and they have to modify the firmware of a standard Intel NIC to support their internal protocol. After all this is in place their storage LUNs appear as parallel SCSI like service to Linux and Windows hosts, but is actually using the Ethernet protocol at a low level to support attache their shared storage to the hosts. They call the protocol ATA over Ethernet but they could have just as easily called it the Coraid storage protocol.
It is a connectionless protocol which uses Ethernet Layer 2 switching to supply a datagram storage service. Data is packaged into 64KB blocks and then broken up into jumbo frames and sent to the MAC address for the storage drive which somehow maps to a storage server and disk LUN. Data is RAID protected within a storage server.
The advantage of the connectionless protocol is that it is very robust in the face of errors and it can take advantage of any number of parallel paths that are available between the storage and the servers that are using it. (As an aside, another session in Storage Field Day was at Brocade and we got to see some of their SAN fabric switching gear – subject for another post someday).
They showed one animation which had an iSCSI with MPIO transfer a 64Kblock but it ended up only using one of the MPIO paths because the other was only used in failure scenarios. They then showed their approach and it used all the paths that were between the server and the storage.
Apparently, in native mode (whatever that is), LUNs are limited in size to something less than a disk device but they seem to have a LVM/virtualization server that is somehow both out of band that provides multi-disk LUNs, replication, snapshot and other advanced services. We didn’t talk about this capability much.
Coraid said they have 1500 customers, plenty with more than a PB. In fact they handed out tokens which provided us honorary memberships in the PB club. They mentioned FORD, NASA, SONY and a bunch of other well known G100 companies around the world which has lot’s of Coraid. Also it appears there is quite a lot of Coraid in DOD installations around the world. In fact, one of the Execs at the session was a former IT exec for the Marines who liked it so much he now works for Coraid.
This was the second to last stop of the day so by this time the Storage Field Day team was somewhat dragging but we managed to ask a bunch of pertinent questions. If you want to see what it looks like I suggest you watch the video (which can be seen here, I’m the handsome guy in the brown sports coat close to the front of the room).
Don’t know why I have never heard of them before but they are unlike anything else I am aware of in the storage industry. They certainly are a block storage system but seem to have taken DAS and somehow put it out as shared storage, at the other end of an ethernet plug…
In my opinion, I would say Coraid has an awareness gap. Although with the customer sizes they were mentioning, it seems that word of mouth is somehow working ok for them. Maybe a more aggressive sales/marketing team could take it to the next level. But I don’t know if they want it that much and if they did it might bring another level of competition to their market.
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Anybody out there a current EtherDrive user? If so what do you think about their storage??