vblade/README

This is a beta release of vblade, the virtual EtherDrive (R) blade.
The vblade is a program that makes a seekable file available over an
ethernet local area network (LAN) via the ATA over Ethernet (AoE)
protocol.

The seekable file is typically a block device like /dev/md0 but even
regular files will work.  When vblade exports the block storage over
AoE it becomes a storage target.  Another host on the same LAN can
access the storage if it has a compatible aoe kernel driver.

The Linux aoe driver for the 2.6 kernel is compatible if you use
aoe-2.6-7 or newer.  You can use older aoe drivers but you will only
be able to see one vblade per MAC address.

The following command should build the vblade program:

  make

There is a "vbladed" script that daemonizes the program and sends its
output to the logger program.  Make sure you have logger installed if
you would like to run vblade as a daemon with the vbladed script.

  ecashin@kokone vblade$ echo 'I have logger' | logger
  ecashin@kokone vblade$ tail -3 /var/log/messages
  Feb  8 14:52:49 kokone -- MARK --
  Feb  8 15:12:49 kokone -- MARK --
  Feb  8 15:19:56 kokone logger: I have logger

Here is a short example showing how to export a block device with a
vblade.  (This is a loop device backed by a sparse file, but you could
use any seekable file instead of /dev/loop7.)

  ecashin@kokone vblade$ make
  cc -Wall   -c -o aoe.o aoe.c
  cc -Wall   -c -o linux.o linux.c
  cc -Wall   -c -o ata.o ata.c
  cc -o vblade aoe.o linux.o ata.o
  ecashin@kokone vblade$ su
  Password: 
  root@kokone vblade# modprobe loop
  root@kokone vblade# dd if=/dev/zero bs=1k count=1 seek=`expr 1024 \* 4096` of=bd
  -file
  1+0 records in
  1+0 records out
  1024 bytes transferred in 0.009901 seconds (103423 bytes/sec)
  root@kokone vblade# losetup /dev/loop7 bd-file  
  root@kokone vblade# ./vblade 9 0 eth0 /dev/loop7 
  ioctl returned 0
  4294968320 bytes
  pid 16967: e9.0, 8388610 sectors

Here's how you can use the Linux aoe driver to access the storage from
another host on the LAN.

  ecashin@kokone ecashin$ ssh makki
  Last login: Mon Feb  7 10:25:04 2005
  ecashin@makki ~$ su
  Password: 
  root@makki ecashin# modprobe aoe
  root@makki ecashin# aoe-stat
      e9.0            eth1              up
  root@makki ecashin# mkfs -t ext3 /dev/etherd/e9.0
  mke2fs 1.35 (28-Feb-2004)
...
  Creating journal (8192 blocks): done
  Writing superblocks and filesystem accounting information: done
  
  This filesystem will be automatically checked every 24 mounts or
  180 days, whichever comes first.  Use tune2fs -c or -i to override.
  root@makki ecashin# mkdir /mnt/e9.0
  root@makki ecashin# mount /dev/etherd/e9.0 /mnt/e9.0
  root@makki ecashin# echo hooray > /mnt/e9.0/test.txt
  root@makki ecashin# cat /mnt/e9.0/test.txt
  hooray

Remember: be as careful with these devices as you would with /dev/hda!