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Use the specified protocol on this connection. The supported protocols are:
A Writes to the DRBD device complete as soon as they have reached the local disk and the TCP/IP send buffer.
B Writes to the DRBD device complete as soon as they have reached the local disk, and all peers have acknowledged the receipt of the write requests.
C Writes to the DRBD device complete as soon as they have reached the local and all remote disks.
rcvbuf-size size
Configure the size of the TCP/IP receive buffer. A value of 0 (the default) causes the buffer size to adjust dynamically. This parameter usually does not need to be set, but it can be set to a value up to 10 MiB. The default unit is bytes.
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This option helps to solve the cases when the outcome of the resync decision is incompatible with the current role assignment in the cluster. The defined policies are:
disconnect No automatic resynchronization, simply disconnect.
violently Resync to the primary node is allowed, violating the assumption that data on a block device are stable for one of the nodes. Do not use this option, it is dangerous.
call-pri-lost Call the pri-lost handler on one of the machines. The handler is expected to reboot the machine, which puts it into secondary role.
shared-secret secret
Configure the shared secret used for peer authentication. The secret is a string of up to 64 characters. Peer authentication also requires the cram-hmac-alg parameter to be set.
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Determine how to deal with I/O requests when the requested data is not available locally or remotely (for example, when all disks have failed). The defined policies are:
io-error System calls fail with errno set to EIO.
suspend-io The resource suspends I/O. I/O can be resumed by (re)attaching the lower-level device, by connecting to a peer which has access to the data, or by forcing DRBD to resume I/O with drbdadm resume-io res. When no data is available, forcing I/O to resume will result in the same behavior as the io-error policy.
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This setting is available since DRBD 8.3.9; the default policy is io-error.
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If after the last finished write request no new write request gets issued for expiry-time, then a peer-ack packet is sent. If a new write request is issued before the timer expires, the timer gets reset to expiry-time. (Note: peer-ack packets may be sent due to other reasons as well, e.g. membership changes or the peer-ack-window option.) This parameter may influence resync behavior on remote nodes. Peer nodes need to wait until they receive an peer-ack for releasing a lock on an AL-extent. Resync operations between peers may need to wait for for these locks. The default value for peer-ack-delay is 100 milliseconds, the default unit is milliseconds. This option is available since 9.0.0.
quorum value
When activated, a cluster partition requires quorum in order to modify the replicated data set. That means a node in the cluster partition can only be promoted to primary if the cluster partition has quorum. Every node with a disk directly connected to the node that should be promoted counts. If a primary node should execute a write request, but the cluster partition has lost quorum, it will freeze IO or reject the write request with an error (depending on the on-no-quorum setting). Upon loosing quorum a primary always invokes the quorum-lost handler. The handler is intended for notification purposes, its return code is ignored. The option's value might be set to off, majority, all or a numeric value. If you set it to a numeric value, make sure that the value is greater than half of your number of nodes. Quorum is a mechanism to avoid data divergence, it might be used instead of fencing when there are more than two repicas. It defaults to off If all missing nodes are marked as outdated, a partition always has quorum, no matter how small it is. I.e. If you disconnect all secondary nodes gracefully a single primary continues to operate. In the moment a single secondary is lost, it has to be assumed that it forms a partition with all the missing outdated nodes. In case my partition might be smaller than the other, quorum is lost in this moment. In case you want to allow permanently diskless nodes to gain quorum it is recommendet to not use majority or all. It is recommended to specify an absolute number, since DBRD's heuristic to determine the complete number of diskfull nodes in the cluster is unreliable. The quorum implementation is available starting with the DRBD kernel driver version 9.0.7.
quorum-minimum-redundancy value
This option sets the minimal required number of nodes with an UpToDate disk to allow the partition to gain quorum. This is a different requirement than the plain quorum option expresses. The option's value might be set to off, majority, all or a numeric value. If you set it to a numeric value, make sure that the value is greater than half of your number of nodes. In case you want to allow permanently diskless nodes to gain quorum it is recommendet to not use majority or all. It is recommended to specify an absolute number, since DBRD's heuristic to determine the complete number of diskfull nodes in the cluster is unreliable. This option is available starting with the DRBD kernel driver version 9.0.10.
on-no-quorum {io-error | suspend-io}
By default DRBD freezes IO on a device, that lost quorum. By setting the on-no-quorum to io-error it completes all IO operations with an error if quorum ist lost. The on-no-quorum options is available starting with the DRBD kernel driver version 9.0.8.
startup 섹션
The parameters in this section define the behavior of DRBD at system startup time, in the DRBD init script. They have no effect once the system is up and running.
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