1# SPDX-License-Identifier: GPL-2.0 2# 3# DRBD device driver configuration 4# 5 6comment "DRBD disabled because PROC_FS or INET not selected" 7 depends on PROC_FS='n' || INET='n' 8 9config BLK_DEV_DRBD 10 tristate "DRBD Distributed Replicated Block Device support" 11 depends on PROC_FS && INET 12 select LRU_CACHE 13 select LIBCRC32C 14 help 15 16 NOTE: In order to authenticate connections you have to select 17 CRYPTO_HMAC and a hash function as well. 18 19 DRBD is a shared-nothing, synchronously replicated block device. It 20 is designed to serve as a building block for high availability 21 clusters and in this context, is a "drop-in" replacement for shared 22 storage. Simplistically, you could see it as a network RAID 1. 23 24 Each minor device has a role, which can be 'primary' or 'secondary'. 25 On the node with the primary device the application is supposed to 26 run and to access the device (/dev/drbdX). Every write is sent to 27 the local 'lower level block device' and, across the network, to the 28 node with the device in 'secondary' state. The secondary device 29 simply writes the data to its lower level block device. 30 31 DRBD can also be used in dual-Primary mode (device writable on both 32 nodes), which means it can exhibit shared disk semantics in a 33 shared-nothing cluster. Needless to say, on top of dual-Primary 34 DRBD utilizing a cluster file system is necessary to maintain for 35 cache coherency. 36 37 For automatic failover you need a cluster manager (e.g. heartbeat). 38 See also: https://www.drbd.org/, http://www.linux-ha.org 39 40 If unsure, say N. 41 42config DRBD_FAULT_INJECTION 43 bool "DRBD fault injection" 44 depends on BLK_DEV_DRBD 45 help 46 47 Say Y here if you want to simulate IO errors, in order to test DRBD's 48 behavior. 49 50 The actual simulation of IO errors is done by writing 3 values to 51 /sys/module/drbd/parameters/ 52 53 enable_faults: bitmask of... 54 1 meta data write 55 2 read 56 4 resync data write 57 8 read 58 16 data write 59 32 data read 60 64 read ahead 61 128 kmalloc of bitmap 62 256 allocation of peer_requests 63 512 insert data corruption on receiving side 64 65 fault_devs: bitmask of minor numbers 66 fault_rate: frequency in percent 67 68 Example: Simulate data write errors on /dev/drbd0 with a probability of 5%. 69 echo 16 > /sys/module/drbd/parameters/enable_faults 70 echo 1 > /sys/module/drbd/parameters/fault_devs 71 echo 5 > /sys/module/drbd/parameters/fault_rate 72 73 If unsure, say N. 74