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