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Documentation / aoe / aoe.txt




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Based on kernel version 3.13. Page generated on 2014-01-20 22:00 EST.

1	ATA over Ethernet is a network protocol that provides simple access to
2	block storage on the LAN.
3	
4	  http://support.coraid.com/documents/AoEr11.txt
5	
6	The 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	
10	It has many tips and hints!  Please see, especially, recommended
11	tunings for virtual memory:
12	
13	  http://support.coraid.com/support/linux/EtherDrive-2.6-HOWTO-5.html#ss5.19
14	
15	The aoetools are userland programs that are designed to work with this
16	driver.  The aoetools are on sourceforge.
17	
18	  http://aoetools.sourceforge.net/
19	
20	The scripts in this Documentation/aoe directory are intended to
21	document the use of the driver and are not necessary if you install
22	the aoetools.
23	
24	
25	CREATING 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	
41	USING 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	
67	USING 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	
116	DRIVER 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.
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