1ATA over Ethernet is a network protocol that provides simple access to
2block storage on the LAN.
3
4  http://support.coraid.com/documents/AoEr11.txt
5
6The EtherDrive (R) HOWTO for 2.6 and 3.x kernels is found at ...
7
8  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO.html
9
10It has many tips and hints!  Please see, especially, recommended
11tunings for virtual memory:
12
13  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
14
15The aoetools are userland programs that are designed to work with this
16driver.  The aoetools are on sourceforge.
17
18  http://aoetools.sourceforge.net/
19
20The scripts in this Documentation/aoe directory are intended to
21document the use of the driver and are not necessary if you install
22the aoetools.
23
24
25CREATING DEVICE NODES
26
27  Users of udev should find the block device nodes created
28  automatically, but to create all the necessary device nodes, use the
29  udev configuration rules provided in udev.txt (in this directory).
30
31  There is a udev-install.sh script that shows how to install these
32  rules on your system.
33
34  There is also an autoload script that shows how to edit
35  /etc/modprobe.d/aoe.conf to ensure that the aoe module is loaded when
36  necessary.  Preloading the aoe module is preferable to autoloading,
37  however, because AoE discovery takes a few seconds.  It can be
38  confusing when an AoE device is not present the first time the a
39  command is run but appears a second later.
40
41USING DEVICE NODES
42
43  "cat /dev/etherd/err" blocks, waiting for error diagnostic output,
44  like any retransmitted packets.
45
46  "echo eth2 eth4 > /dev/etherd/interfaces" tells the aoe driver to
47  limit ATA over Ethernet traffic to eth2 and eth4.  AoE traffic from
48  untrusted networks should be ignored as a matter of security.  See
49  also the aoe_iflist driver option described below.
50
51  "echo > /dev/etherd/discover" tells the driver to find out what AoE
52  devices are available.
53
54  In the future these character devices may disappear and be replaced
55  by sysfs counterparts.  Using the commands in aoetools insulates
56  users from these implementation details.
57
58  The block devices are named like this:
59
60	e{shelf}.{slot}
61	e{shelf}.{slot}p{part}
62
63  ... so that "e0.2" is the third blade from the left (slot 2) in the
64  first shelf (shelf address zero).  That's the whole disk.  The first
65  partition on that disk would be "e0.2p1".
66
67USING SYSFS
68
69  Each aoe block device in /sys/block has the extra attributes of
70  state, mac, and netif.  The state attribute is "up" when the device
71  is ready for I/O and "down" if detected but unusable.  The
72  "down,closewait" state shows that the device is still open and
73  cannot come up again until it has been closed.
74
75  The mac attribute is the ethernet address of the remote AoE device.
76  The netif attribute is the network interface on the localhost
77  through which we are communicating with the remote AoE device.
78
79  There is a script in this directory that formats this information in
80  a convenient way.  Users with aoetools should use the aoe-stat
81  command.
82
83  root@makki root# sh Documentation/aoe/status.sh 
84     e10.0            eth3              up
85     e10.1            eth3              up
86     e10.2            eth3              up
87     e10.3            eth3              up
88     e10.4            eth3              up
89     e10.5            eth3              up
90     e10.6            eth3              up
91     e10.7            eth3              up
92     e10.8            eth3              up
93     e10.9            eth3              up
94      e4.0            eth1              up
95      e4.1            eth1              up
96      e4.2            eth1              up
97      e4.3            eth1              up
98      e4.4            eth1              up
99      e4.5            eth1              up
100      e4.6            eth1              up
101      e4.7            eth1              up
102      e4.8            eth1              up
103      e4.9            eth1              up
104
105  Use /sys/module/aoe/parameters/aoe_iflist (or better, the driver
106  option discussed below) instead of /dev/etherd/interfaces to limit
107  AoE traffic to the network interfaces in the given
108  whitespace-separated list.  Unlike the old character device, the
109  sysfs entry can be read from as well as written to.
110
111  It's helpful to trigger discovery after setting the list of allowed
112  interfaces.  The aoetools package provides an aoe-discover script
113  for this purpose.  You can also directly use the
114  /dev/etherd/discover special file described above.
115
116DRIVER OPTIONS
117
118  There is a boot option for the built-in aoe driver and a
119  corresponding module parameter, aoe_iflist.  Without this option,
120  all network interfaces may be used for ATA over Ethernet.  Here is a
121  usage example for the module parameter.
122
123    modprobe aoe_iflist="eth1 eth3"
124
125  The aoe_deadsecs module parameter determines the maximum number of
126  seconds that the driver will wait for an AoE device to provide a
127  response to an AoE command.  After aoe_deadsecs seconds have
128  elapsed, the AoE device will be marked as "down".  A value of zero
129  is supported for testing purposes and makes the aoe driver keep
130  trying AoE commands forever.
131
132  The aoe_maxout module parameter has a default of 128.  This is the
133  maximum number of unresponded packets that will be sent to an AoE
134  target at one time.
135
136  The aoe_dyndevs module parameter defaults to 1, meaning that the
137  driver will assign a block device minor number to a discovered AoE
138  target based on the order of its discovery.  With dynamic minor
139  device numbers in use, a greater range of AoE shelf and slot
140  addresses can be supported.  Users with udev will never have to
141  think about minor numbers.  Using aoe_dyndevs=0 allows device nodes
142  to be pre-created using a static minor-number scheme with the
143  aoe-mkshelf script in the aoetools.
144