# SPDX-License-Identifier: GPL-2.0-only
java.lang.NullPointerException
# DRBD device driver configuration
java.lang.NullPointerException
comment
"DRBD disabled because PROC_FS or INET not selected"
depends on PROC_FS=
'n' || INET=
'n'
config BLK_DEV_DRBD
tristate
"DRBD Distributed Replicated Block Device support"
depends on PROC_FS && INET
select LRU_CACHE
select CRC32
help
NOTE: In order to authenticate connections you have to select
CRYPTO_HMAC
and a hash function as well.
DRBD is a shared-nothing, synchronously replicated block device. It
is designed to serve as a building block
for high availability
clusters
and in
this context, is a
"drop-in" replacement
for shared
storage. Simplistically, you could see it as a network RAID 1.
Each minor device has a role, which can be
'primary' or 'secondary'.
On the node with the primary device the application is supposed to
run
and to access the device (/dev/drbdX). Every write is sent to
the local
'lower level block device' and, across the network, to the
node with the device in
'secondary' state. The secondary device
simply writes the data to its lower level block device.
DRBD can also be used in dual-Primary mode (device writable on both
nodes), which means it can exhibit shared disk semantics in a
shared-nothing cluster. Needless to say, on top of dual-Primary
DRBD utilizing a cluster file system is necessary to maintain
for
cache coherency.
For automatic failover you need a cluster manager (e.g. heartbeat).
See also: https:
//www.drbd.org/, http://www.linux-ha.org
If unsure, say N.
config DRBD_FAULT_INJECTION
bool "DRBD fault injection"
depends on BLK_DEV_DRBD
help
Say Y here
if you want to simulate IO errors, in order to test DRBD
's
behavior.
The actual simulation of IO errors is done by writing 3 values to
/sys/module/drbd/parameters/
enable_faults: bitmask of...
1 meta data write
2 read
4 resync data write
8 read
16 data write
32 data read
64 read ahead
128 kmalloc of bitmap
256 allocation of peer_requests
512 insert data corruption on receiving side
fault_devs: bitmask of minor numbers
fault_rate: frequency in percent
Example: Simulate data write errors on /dev/drbd0 with a probability of 5%.
echo 16 > /sys/module/drbd/parameters/enable_faults
echo 1 > /sys/module/drbd/parameters/fault_devs
echo 5 > /sys/module/drbd/parameters/fault_rate
If unsure, say N.
