LINBIT DRBD (historical). Contribute to LINBIT/drbd development by creating an account on GitHub. Simply recreate the metadata for the new devices on server0, and bring them up: # drbdadm create-md all # drbdadm up all. You should then. DRBD Third Node Replication With Debian Etch The recent release of DRBD now includes The Third Node feature as a freely available component.

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Scroll to navigation DRBD. You can disable the IP verification with this option. Please participate in DRBD’s online usage counter [2].

drbdsetup(8) — drbd-utils — Debian testing — Debian Manpages

The most convenient way to do so is to set this option to yes. Valid protocol specifiers are A, B, and C. If a node becomes a 88.3 primary, it tries to fence the peer’s disk. This is done by calling the fence-peer handler. The handler is supposed to reach the other node over alternative communication paths and call ‘ drbdadm outdate res ‘ there. If a node becomes a disconnected primary, it freezes all its IO operations and calls its fence-peer handler.

The fence-peer handler is supposed to reach the peer over alternative communication paths and call ‘drbdadm outdate res’ there. In case it cannot reach the peer it should stonith the peer.

IO is resumed as soon as the situation is resolved. In case your handler fails, you can resume IO with the resume-io command.

At the time of writing the only known drivers which have such a function are: DRBD has four implementations to express write-after-write dependencies to its backing storage device. DRBD will use the first method that is supported by the backing storage device and that is not disabled by the user. The first requires that the driver of the backing storage device support barriers called ‘tagged command queuing’ in SCSI and ‘native command queuing’ in SATA speak.

The use of this method can be disabled by the no-disk-barrier option. The second requires that the backing device support disk flushes called ‘force unit access’ in the drive vendors speak.

The use of this method can be disabled using the no-disk-flushes option. The third method is simply to let write requests drain before write requests of a new reordering domain are issued. This was the only implementation before 8. The fourth method is to not express write-after-write dependencies to the backing store at all, by also specifying no-disk-drain. Do not use no-disk-drain.


Disables the use of disk flushes and barrier BIOs when accessing the meta data device. See the notes on no-disk-flushes. A known example is: Then you might see “bio would need to, but cannot, be split: The disk state advances to diskless, as soon as the backing block device has finished all IO requests.

The default value is 0, i. You can specify smaller or larger values. Larger values are appropriate for reasonable write throughput with protocol A over high latency networks. Values below 32K do not make sense. Usually this should be left at its default. Setting the size value to 0 means that the kernel frbd autotune this. This setting has no effect with recent kernels that use explicit on-stack plugging upstream Linux kernel 2.

Auto sync from the node that was primary before the split-brain situation happened. Auto sync from the node that became primary as second during the split-brain situation.

In case one node did not write anything since the split brain became evident, sync from the node that wrote something to the node that did not write anything. In case none wrote anything this policy uses a random decision to perform a “resync” of 0 blocks. In case both have written something this policy disconnects the nodes. Auto sync from the node that touched more blocks during the split brain situation.

Drbbd the version of the secondary if the outcome of the after-sb-0pri algorithm would also destroy the current secondary’s data. Always take the decision of the after-sb-0pri algorithm, even if that causes an erratic change of the primary’s view of the data. This is only useful if you use a one-node FS i.

Always honor the outcome of the after-sb-0pri algorithm. In case it decides the current secondary has the right data, it calls the “pri-lost-after-sb” handler on the current primary.

Call the “pri-lost-after-sb” helper program on one of the machines. This program is expected to reboot the machine, i. Normally the automatic after-split-brain policies are only used if current states dfbd the UUIDs do not indicate the presence of a third node. This option helps to solve the cases when the outcome of the resync decision is incompatible with the current role assignment in the cluster.

Sync to the primary node is allowed, violating the assumption that data on a block device are stable for one of the nodes.

Dangerous, do not use. Call the “pri-lost” helper program on one of the machines. DRBD can ensure the data integrity of the user’s data on the network by comparing hash values. It turned out that there is at crbd one network stack that performs worse when one uses this hinting method. That means it will slow down the application that generates the write requests that cause DRBD to send more data down that TCP connection. By setting this option you can make the init script to continue to wait even if the device pair had a split brain situation and therefore refuses to connect.


Sets on which node the device should be promoted to primary role by the init script.

drbd-8.3 man page

The node-name might either be a host name or the keyword both. When this option is not set the devices stay in secondary role on both nodes. Usually one delegates the role assignment to a cluster manager e. Usually wfc-timeout and degr-wfc-timeout are ignored for stacked devices, instead twice the amount of connect-int is used for the connection timeouts.

With the stacked-timeouts keyword you disable this, and force DRBD to mind the wfc-timeout and degr-wfc-timeout statements.

DRBD replace a failed disk – Server Fault

Only do that if the peer of the stacked resource is usually not available or will usually not become primary. By using this option incorrectly, you run the risk of causing unexpected split brain. During online verification as initiated by the verify sub-commandrather than doing a bit-wise comparison, DRBD applies a hash function to the contents of every block being verified, and compares that hash with the peer.

This option defines the hash algorithm being used for that purpose. It can be set to any of the kernel’s data digest algorithms. In a typical kernel configuration you should have at least one of md5sha1and crc32c available. By default this is not enabled; you must set this option explicitly in order to be able to use on-line device verification.

A resync process sends all marked data blocks from the drvd to the destination node, as long as no csums-alg is given.

When one is specified the resync process exchanges hash values of all marked blocks first, and sends only those data blocks that have different hash values. A node that is primary and sync-source has to schedule application IO requests and resync IO requests. This setting controls what dbrd to IO requests on a degraded, disk less node I. The available policies are io-error and suspend-io.