144 lines
5.7 KiB
Plaintext
144 lines
5.7 KiB
Plaintext
ATA over Ethernet is a network protocol that provides simple access to
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block storage on the LAN.
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http://support.coraid.com/documents/AoEr11.txt
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The EtherDrive (R) HOWTO for 2.6 and 3.x kernels is found at ...
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http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO.html
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It has many tips and hints! Please see, especially, recommended
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tunings for virtual memory:
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http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
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The aoetools are userland programs that are designed to work with this
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driver. The aoetools are on sourceforge.
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http://aoetools.sourceforge.net/
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The scripts in this Documentation/aoe directory are intended to
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document the use of the driver and are not necessary if you install
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the aoetools.
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CREATING DEVICE NODES
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Users of udev should find the block device nodes created
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automatically, but to create all the necessary device nodes, use the
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udev configuration rules provided in udev.txt (in this directory).
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There is a udev-install.sh script that shows how to install these
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rules on your system.
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There is also an autoload script that shows how to edit
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/etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
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necessary. Preloading the aoe module is preferable to autoloading,
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however, because AoE discovery takes a few seconds. It can be
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confusing when an AoE device is not present the first time the a
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command is run but appears a second later.
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USING DEVICE NODES
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"cat /dev/etherd/err" blocks, waiting for error diagnostic output,
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like any retransmitted packets.
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"echo eth2 eth4 > /dev/etherd/interfaces" tells the aoe driver to
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limit ATA over Ethernet traffic to eth2 and eth4. AoE traffic from
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untrusted networks should be ignored as a matter of security. See
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also the aoe_iflist driver option described below.
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"echo > /dev/etherd/discover" tells the driver to find out what AoE
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devices are available.
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In the future these character devices may disappear and be replaced
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by sysfs counterparts. Using the commands in aoetools insulates
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users from these implementation details.
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The block devices are named like this:
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e{shelf}.{slot}
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e{shelf}.{slot}p{part}
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... so that "e0.2" is the third blade from the left (slot 2) in the
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first shelf (shelf address zero). That's the whole disk. The first
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partition on that disk would be "e0.2p1".
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USING SYSFS
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Each aoe block device in /sys/block has the extra attributes of
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state, mac, and netif. The state attribute is "up" when the device
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is ready for I/O and "down" if detected but unusable. The
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"down,closewait" state shows that the device is still open and
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cannot come up again until it has been closed.
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The mac attribute is the ethernet address of the remote AoE device.
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The netif attribute is the network interface on the localhost
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through which we are communicating with the remote AoE device.
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There is a script in this directory that formats this information in
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a convenient way. Users with aoetools should use the aoe-stat
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command.
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root@makki root# sh Documentation/aoe/status.sh
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e10.0 eth3 up
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e10.1 eth3 up
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e10.2 eth3 up
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e10.3 eth3 up
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e10.4 eth3 up
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e10.5 eth3 up
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e10.6 eth3 up
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e10.7 eth3 up
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e10.8 eth3 up
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e10.9 eth3 up
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e4.0 eth1 up
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e4.1 eth1 up
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e4.2 eth1 up
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e4.3 eth1 up
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e4.4 eth1 up
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e4.5 eth1 up
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e4.6 eth1 up
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e4.7 eth1 up
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e4.8 eth1 up
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e4.9 eth1 up
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Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
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option discussed below) instead of /dev/etherd/interfaces to limit
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AoE traffic to the network interfaces in the given
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whitespace-separated list. Unlike the old character device, the
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sysfs entry can be read from as well as written to.
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It's helpful to trigger discovery after setting the list of allowed
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interfaces. The aoetools package provides an aoe-discover script
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for this purpose. You can also directly use the
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/dev/etherd/discover special file described above.
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DRIVER OPTIONS
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There is a boot option for the built-in aoe driver and a
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corresponding module parameter, aoe_iflist. Without this option,
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all network interfaces may be used for ATA over Ethernet. Here is a
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usage example for the module parameter.
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modprobe aoe_iflist="eth1 eth3"
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The aoe_deadsecs module parameter determines the maximum number of
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seconds that the driver will wait for an AoE device to provide a
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response to an AoE command. After aoe_deadsecs seconds have
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elapsed, the AoE device will be marked as "down". A value of zero
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is supported for testing purposes and makes the aoe driver keep
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trying AoE commands forever.
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The aoe_maxout module parameter has a default of 128. This is the
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maximum number of unresponded packets that will be sent to an AoE
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target at one time.
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The aoe_dyndevs module parameter defaults to 1, meaning that the
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driver will assign a block device minor number to a discovered AoE
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target based on the order of its discovery. With dynamic minor
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device numbers in use, a greater range of AoE shelf and slot
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addresses can be supported. Users with udev will never have to
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think about minor numbers. Using aoe_dyndevs=0 allows device nodes
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to be pre-created using a static minor-number scheme with the
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aoe-mkshelf script in the aoetools.
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