Issue link: https://epubs.iltanet.org/i/4636
www.iltanet.org Infrastructure Technologies 23 The computer that the disk will be attached to will need an initiator, which is usually software and an Ethernet network interface card (NIC). The initiator sends out a message to detect AoE target devices, which are software-based disk storage appliances with an Ethernet NIC. The network interface card can be shared with other network traffic, but performance is better with a dedicated NIC. Devices exposed as AoE targets can also be combined in a software-based redundant array of inexpensive disks (RAID) or mirror on the host adding additional layers of redundancy. AOE-SPEAK In AoE terminology, "disk" is a logical term. A disk could be an actual physical disk on a computer, or it could be a RAID device, a file on a physical disk or a RAID device exposed as a disk. This is where the flexibility of AoE starts to show. To get a feel for how AoE works, you could install Linux on a desktop computer or displaced server and manually configure the partitions on the system to leave a large extra partition on the Linux computer. This large partition can be exposed to other computers on the network using the AoE vblade tools. The vblade tools, of which there are several varieties, allow you to create a "virtual blade." In AoE parlance, this virtual blade is a "disk." AoE also makes use of "shelves" and "slots" to identify individual disks. These are arbitrary numbers assigned by the administrator. The shelf would represent the device exposing the disks to the AoE network, and the slot is the individual disk. Slot six in shelf one would then be expressed as "1.6," and this numerical expression is called a logical unit number (LUN) just as it is in SCSI and iSCSI. Also, as with iSCSI, these devices can be set, or masked, to only respond to certain initiators. The Linux command below illustrates how easy it is to expose an AoE device to the network. vblade 11 1 eth1 /data/3TB This command creates a vblade called "shelf 11, slot 1," or "11.1" on the Ethernet 1, (probably the second NIC in the computer), and exposes a file called "/data/3TB." The number choice for the shelf and the slot is completely arbitrary and decided by the administrator for ease of management. From a remote machine, the file will look just like a disk that can be formatted and written to use any file system present on the accessing system. This could be new technology file system (NTFS) for Windows or one of a variety of file systems usable by Linux and UNIX systems. The Linux command below would do the same thing for a Linux disk partition. vblade 11 2 eth1 /dev/sdd5 Windows AoE initiator software called StarPort is available from Rocket Division Software as downloadable trial software. Vblades, like those created above, could be accessed, mounted and formatted from Windows using StarPort. MAxIMIZING AOE PERFORMANCE Like iSCSI, ATA over Ethernet should be on its own network; although if you are using Ethernet switches, it probably is already on an isolated network by virtue of that switching technology design. Virtual LANs can also be used on an Ethernet switch to isolate AoE traffic. For gigabit