Documentation/aoe/aoe.txt

   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.