linux/Documentation/aoe/aoe.txt
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   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".
 129
 130  The aoe_maxout module parameter has a default of 128.  This is the
 131  maximum number of unresponded packets that will be sent to an AoE
 132  target at one time.
 133
 134  The aoe_dyndevs module parameter defaults to 1, meaning that the
 135  driver will assign a block device minor number to a discovered AoE
 136  target based on the order of its discovery.  With dynamic minor
 137  device numbers in use, a greater range of AoE shelf and slot
 138  addresses can be supported.  Users with udev will never have to
 139  think about minor numbers.  Using aoe_dyndevs=0 allows device nodes
 140  to be pre-created using a static minor-number scheme with the
 141  aoe-mkshelf script in the aoetools.
 142
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