drivers/block/drbd/Kconfig

   1 #
   2 # DRBD device driver configuration
   3 #
   4
   5 comment "DRBD disabled because PROC_FS, INET or CONNECTOR not selected"
   6         depends on !PROC_FS || !INET || !CONNECTOR
   7
   8 config BLK_DEV_DRBD
   9         tristate "DRBD Distributed Replicated Block Device support"
  10         depends on PROC_FS && INET && CONNECTOR
  11         select LRU_CACHE
  12         default n
  13         help
  14
  15           NOTE: In order to authenticate connections you have to select
  16           CRYPTO_HMAC and a hash function as well.
  17
  18           DRBD is a shared-nothing, synchronously replicated block device. It
  19           is designed to serve as a building block for high availability
  20           clusters and in this context, is a "drop-in" replacement for shared
  21           storage. Simplistically, you could see it as a network RAID 1.
  22
  23           Each minor device has a role, which can be 'primary' or 'secondary'.
  24           On the node with the primary device the application is supposed to
  25           run and to access the device (/dev/drbdX). Every write is sent to
  26           the local 'lower level block device' and, across the network, to the
  27           node with the device in 'secondary' state.  The secondary device
  28           simply writes the data to its lower level block device.
  29
  30           DRBD can also be used in dual-Primary mode (device writable on both
  31           nodes), which means it can exhibit shared disk semantics in a
  32           shared-nothing cluster.  Needless to say, on top of dual-Primary
  33           DRBD utilizing a cluster file system is necessary to maintain for
  34           cache coherency.
  35
  36           For automatic failover you need a cluster manager (e.g. heartbeat).
  37           See also: http://www.drbd.org/, http://www.linux-ha.org
  38
  39           If unsure, say N.
  40
  41 config DRBD_TRACE
  42         tristate "DRBD tracing"
  43         depends on BLK_DEV_DRBD
  44         select TRACEPOINTS
  45         default n
  46         help
  47
  48           Say Y here if you want to be able to trace various events in DRBD.
  49
  50           If unsure, say N.
  51
  52 config DRBD_FAULT_INJECTION
  53         bool "DRBD fault injection"
  54         depends on BLK_DEV_DRBD
  55         help
  56
  57           Say Y here if you want to simulate IO errors, in order to test DRBD's
  58           behavior.
  59
  60           The actual simulation of IO errors is done by writing 3 values to
  61           /sys/module/drbd/parameters/
  62
  63           enable_faults: bitmask of...
  64           1     meta data write
  65           2               read
  66           4     resync data write
  67           8                 read
  68           16    data write
  69           32    data read
  70           64    read ahead
  71           128   kmalloc of bitmap
  72           256   allocation of EE (epoch_entries)
  73
  74           fault_devs: bitmask of minor numbers
  75           fault_rate: frequency in percent
  76
  77           Example: Simulate data write errors on /dev/drbd0 with a probability of 5%.
  78                 echo 16 > /sys/module/drbd/parameters/enable_faults
  79                 echo 1 > /sys/module/drbd/parameters/fault_devs
  80                 echo 5 > /sys/module/drbd/parameters/fault_rate
  81
  82           If unsure, say N.