This guide has been released to the DRBD community, and its authors The DRBD User’s Guide v. Pacemaker CRM configuration. This document will cover the basics of setting up a third node on a standard Debian Etch installation. At the end of this tutorial you will have a DRBD device that. There may be multiple resource sections in a single file. For more examples, please have a look at the DRBD User’s Guide[1].
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DRBD consists of low-level user-space components which interact with the kernel and perform basic operations drbdsetupdrbdmetaa high-level user-space component which understands and processes the DRBD usef and translates it into basic operations of the low-level components drbdadmand a kernel component. In case it decides the current secondary has the correct data, call the pri-lost-after-sb on the current primary.
(5) — drbd-utils — Debian unstable — Debian Manpages
The optional name is used to refer to the connection in the system log and in other messages. By default this is not enabled. Sections common This section can contain each a diskhandlersnetoptionsand startup section. This can be useful in combination with a cluster manager which cannot manage DRBD resources: Usually contains at least two on sections and at least one connection section. This handler is called if the node is primary, degraded and if the local copy of the data is inconsistent.
Section path Parameters host name [ address [address-family] address ] [ port dbrd ] Defines an endpoint for a connection. Some parameter values have a default scale which applies when a plain number is specified for example Kilo, or times the numeric value. The default size is 0, i. You can change this behavior with the –wait-after-sb option. The default unit is tenths of a second, the default value is 0 which causes DRBD .83 use the value of ping-timeout instead.
Drbd-documentation
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. The default is 0 which disables the check. Take the copy of the current active server. Always honor the outcome of the after-sb-0pri algorithm.
It is advised to use resources which are replicated among more than two nodes instead. You need to specify the HMAC algorithm to enable peer authentication at all. The default value is 0, which disables this mechanism of congestion control, with a maximum of 10 GiBytes.
After the data sync has finished, create the meta-data on data-upper on alphafollowed by foxtrot. This might be used to get notified of DRBD’s state changes by piping the output to another program. You must not use this on pre-existing data! The start-sector will be rounded down to a multiple of 8 sectors 4kB. Sync to the primary node is allowed, violating the assumption that data on a block device are stable for one of the nodes.
Values below 32K do not make sense. As the command states, this is going to overwrite any data on bravo: While disconnect speaks for itself, with the call-pri-lost setting the pri-lost handler is called which is expected to either change the role of the node to secondary, or remove the node from the cluster.
A known example is: This prevents applications from generating further write requests until more buffer space becomes available again. If a node becomes a disconnected primary, it tries to fence the peer’s disk. This handler is called in case the node needs to fence the peer’s disk. The default value for peer-ack-delay is milliseconds, the default unit is milliseconds. Guixe 16, defaultmaximum The options are the same as with the wait-connect command.
The cpu mask is specified as a hexadecimal number. Even read-only access with tools like dumpe2fs 8 and similar is not allowed. A normal configuration file contains two or more on sections for each dgbd.
If af is omitted ipv4 gets used. Because the bitmap typically contains compact areas where all bits are unset clean or set dirtya simple run-length encoding scheme can considerably reduce the network traffic necessary for guiide bitmap exchange.
By using this option incorrectly, you run the risk of causing unexpected split brain. This parameter usually does not need to be set, but it can be set to a value up to 10 MiB. This might cause a full sync, if the UUIDs indicate the presence of a third node.
Before DRBD 9, this could only be done explicitly “drbdadm primary”. However, unaligned partial head or tail areas of discard requests will be silently ignored. Peer authentication also requires a shared-secret to be configured. Online verify would now potentially report tons of spurious differences. It turned out that there is at least one network stack that performs worse when one uses this hinting method. Node identifiers can only be reasssigned in a cluster when the cluster is down.
To avoid possible distributed deadlocks on congestion, this setting is used as a throttle threshold rather than a hard limit. Once more than max-buffers pages are in use, further allocation from this pool is throttled.
During on-line verification, the contents of every block on the local node are compared to those on the peer node. DRBD automatically performs hot area detection.
The node should give up its primary role. By using this option incorrectly, you run the risk of causing unexpected split brain. For example, in a three-node setup nodes A, B, C each with a single device, every node maintains one bitmap for each of its peers.