2Degrees Frost claims to have made the cheapest storage area network (SAN) in the world available for Mac OS X users.
Based on Coraid’s ATA over Ethernet (AoE) technology, Mac EtherDrive comes as a fully configured storage bundles, including a Mac OS X driver.
Customers get networked storage accessed over Ethernet with a lower-level protocol than iSCSI. This means that the TCP/IP processing burden of iSCSI is absent and TCP/IP offload cards (TOEs) are not needed. Coraid calls it a “thin protocol.”
Jim Kemp, Coraid’s CEO, said: “Professional Mac users and administrators now have an effective way to address mass storage needs affordably with a compelling, scalable, flexible, and cost effective storage solution that allows quick access to data.” How quick was not specified; it depends upon the speed of the Ethernet links and the traffic on them. Kemp said: “”On a 1Gbit Ethernet link, AoE can achieve 110MB of throughput without burdening the host processor.”
The networked storage is scalable from a terabyte to multiple petabytes — an upper limit has not yet been found — at a storage cost of US$1.24 per GB, lower than both iSCSI and Fibre Channel SAN storage. It supports RAID levels 0, 1, 5 and 10, and the serial ATA drive modules are hot-swappable.
The Mac cost is higher than for Linux, other Unix, or Windows users. Coraid quoted a price of $0.53 per GB for 7.5TB of EtherDrive storage last year. On its website it’s currently quoting $0.93 per GB.
There are some points to bear in mind. Since AoE is not a routable protocol access is limited to the local Ethernet segment.
The protocol is openly available — its included with the Linux 2.6.11 kernel — but storage products that support it are only available from relatively few suppliers, such as Coraid and, for Mac users, 2DegreesFrost. The Ethernet switches have to have flow control functionality in order to get the best throughput and minimize packet collisions.
Mac OS X users won’t be trying out untested technology; existing Coraid customers include the NASA Goddard Flight Center and the U.S. Geological Survey amongst others.
Coraid’s EtherDrive products are available for both Windows and Unix — Linux, Solaris, BSD — users.