diff --git a/daemons/fenced/pacemaker-fenced.c b/daemons/fenced/pacemaker-fenced.c index 6a094240fb..38557baf13 100644 --- a/daemons/fenced/pacemaker-fenced.c +++ b/daemons/fenced/pacemaker-fenced.c @@ -1,680 +1,679 @@ /* * Copyright 2009-2024 the Pacemaker project contributors * * The version control history for this file may have further details. * * This source code is licensed under the GNU General Public License version 2 * or later (GPLv2+) WITHOUT ANY WARRANTY. */ #include #include #include #include #include #include #include #include #include #include #include // PRIu32, PRIx32 #include #include #include #include #include #include #include #include #include #include #include #include #define SUMMARY "daemon for executing fencing devices in a Pacemaker cluster" char *stonith_our_uname = NULL; long long stonith_watchdog_timeout_ms = 0; GList *stonith_watchdog_targets = NULL; static GMainLoop *mainloop = NULL; gboolean stand_alone = FALSE; gboolean stonith_shutdown_flag = FALSE; static qb_ipcs_service_t *ipcs = NULL; static pcmk__output_t *out = NULL; pcmk__supported_format_t formats[] = { PCMK__SUPPORTED_FORMAT_NONE, PCMK__SUPPORTED_FORMAT_TEXT, PCMK__SUPPORTED_FORMAT_XML, { NULL, NULL, NULL } }; static struct { bool no_cib_connect; gchar **log_files; } options; crm_exit_t exit_code = CRM_EX_OK; static void stonith_cleanup(void); static int32_t st_ipc_accept(qb_ipcs_connection_t * c, uid_t uid, gid_t gid) { if (stonith_shutdown_flag) { crm_info("Ignoring new client [%d] during shutdown", pcmk__client_pid(c)); return -ECONNREFUSED; } if (pcmk__new_client(c, uid, gid) == NULL) { return -ENOMEM; } return 0; } /* Exit code means? */ static int32_t st_ipc_dispatch(qb_ipcs_connection_t * qbc, void *data, size_t size) { uint32_t id = 0; uint32_t flags = 0; int call_options = 0; xmlNode *request = NULL; pcmk__client_t *c = pcmk__find_client(qbc); const char *op = NULL; if (c == NULL) { crm_info("Invalid client: %p", qbc); return 0; } request = pcmk__client_data2xml(c, data, &id, &flags); if (request == NULL) { pcmk__ipc_send_ack(c, id, flags, PCMK__XE_NACK, NULL, CRM_EX_PROTOCOL); return 0; } op = crm_element_value(request, PCMK__XA_CRM_TASK); if(pcmk__str_eq(op, CRM_OP_RM_NODE_CACHE, pcmk__str_casei)) { crm_xml_add(request, PCMK__XA_T, PCMK__VALUE_STONITH_NG); crm_xml_add(request, PCMK__XA_ST_OP, op); crm_xml_add(request, PCMK__XA_ST_CLIENTID, c->id); crm_xml_add(request, PCMK__XA_ST_CLIENTNAME, pcmk__client_name(c)); crm_xml_add(request, PCMK__XA_ST_CLIENTNODE, stonith_our_uname); pcmk__cluster_send_message(NULL, crm_msg_stonith_ng, request); pcmk__xml_free(request); return 0; } if (c->name == NULL) { const char *value = crm_element_value(request, PCMK__XA_ST_CLIENTNAME); c->name = crm_strdup_printf("%s.%u", pcmk__s(value, "unknown"), c->pid); } crm_element_value_int(request, PCMK__XA_ST_CALLOPT, &call_options); crm_trace("Flags %#08" PRIx32 "/%#08x for command %" PRIu32 " from client %s", flags, call_options, id, pcmk__client_name(c)); if (pcmk_is_set(call_options, st_opt_sync_call)) { CRM_ASSERT(flags & crm_ipc_client_response); CRM_LOG_ASSERT(c->request_id == 0); /* This means the client has two synchronous events in-flight */ c->request_id = id; /* Reply only to the last one */ } crm_xml_add(request, PCMK__XA_ST_CLIENTID, c->id); crm_xml_add(request, PCMK__XA_ST_CLIENTNAME, pcmk__client_name(c)); crm_xml_add(request, PCMK__XA_ST_CLIENTNODE, stonith_our_uname); crm_log_xml_trace(request, "ipc-received"); stonith_command(c, id, flags, request, NULL); pcmk__xml_free(request); return 0; } /* Error code means? */ static int32_t st_ipc_closed(qb_ipcs_connection_t * c) { pcmk__client_t *client = pcmk__find_client(c); if (client == NULL) { return 0; } crm_trace("Connection %p closed", c); pcmk__free_client(client); /* 0 means: yes, go ahead and destroy the connection */ return 0; } static void st_ipc_destroy(qb_ipcs_connection_t * c) { crm_trace("Connection %p destroyed", c); st_ipc_closed(c); } static void stonith_peer_callback(xmlNode * msg, void *private_data) { const char *remote_peer = crm_element_value(msg, PCMK__XA_SRC); const char *op = crm_element_value(msg, PCMK__XA_ST_OP); if (pcmk__str_eq(op, STONITH_OP_POKE, pcmk__str_none)) { return; } crm_log_xml_trace(msg, "Peer[inbound]"); stonith_command(NULL, 0, 0, msg, remote_peer); } #if SUPPORT_COROSYNC static void stonith_peer_ais_callback(cpg_handle_t handle, const struct cpg_name *groupName, uint32_t nodeid, uint32_t pid, void *msg, size_t msg_len) { uint32_t kind = 0; xmlNode *xml = NULL; const char *from = NULL; char *data = pcmk__cpg_message_data(handle, nodeid, pid, msg, &kind, &from); if(data == NULL) { return; } if (kind == crm_class_cluster) { xml = pcmk__xml_parse(data); if (xml == NULL) { crm_err("Invalid XML: '%.120s'", data); free(data); return; } crm_xml_add(xml, PCMK__XA_SRC, from); stonith_peer_callback(xml, NULL); } pcmk__xml_free(xml); free(data); return; } static void stonith_peer_cs_destroy(gpointer user_data) { crm_crit("Lost connection to cluster layer, shutting down"); stonith_shutdown(0); } #endif void do_local_reply(const xmlNode *notify_src, pcmk__client_t *client, int call_options) { /* send callback to originating child */ int local_rc = pcmk_rc_ok; int rid = 0; uint32_t ipc_flags = crm_ipc_server_event; if (pcmk_is_set(call_options, st_opt_sync_call)) { CRM_LOG_ASSERT(client->request_id); rid = client->request_id; client->request_id = 0; ipc_flags = crm_ipc_flags_none; } local_rc = pcmk__ipc_send_xml(client, rid, notify_src, ipc_flags); if (local_rc == pcmk_rc_ok) { crm_trace("Sent response %d to client %s", rid, pcmk__client_name(client)); } else { crm_warn("%synchronous reply to client %s failed: %s", (pcmk_is_set(call_options, st_opt_sync_call)? "S" : "As"), pcmk__client_name(client), pcmk_rc_str(local_rc)); } } uint64_t get_stonith_flag(const char *name) { if (pcmk__str_eq(name, PCMK__VALUE_ST_NOTIFY_FENCE, pcmk__str_none)) { return st_callback_notify_fence; } else if (pcmk__str_eq(name, STONITH_OP_DEVICE_ADD, pcmk__str_casei)) { return st_callback_device_add; } else if (pcmk__str_eq(name, STONITH_OP_DEVICE_DEL, pcmk__str_casei)) { return st_callback_device_del; } else if (pcmk__str_eq(name, PCMK__VALUE_ST_NOTIFY_HISTORY, pcmk__str_none)) { return st_callback_notify_history; } else if (pcmk__str_eq(name, PCMK__VALUE_ST_NOTIFY_HISTORY_SYNCED, pcmk__str_none)) { return st_callback_notify_history_synced; } return st_callback_unknown; } static void stonith_notify_client(gpointer key, gpointer value, gpointer user_data) { const xmlNode *update_msg = user_data; pcmk__client_t *client = value; const char *type = NULL; CRM_CHECK(client != NULL, return); CRM_CHECK(update_msg != NULL, return); type = crm_element_value(update_msg, PCMK__XA_SUBT); CRM_CHECK(type != NULL, crm_log_xml_err(update_msg, "notify"); return); if (client->ipcs == NULL) { crm_trace("Skipping client with NULL channel"); return; } if (pcmk_is_set(client->flags, get_stonith_flag(type))) { int rc = pcmk__ipc_send_xml(client, 0, update_msg, crm_ipc_server_event); if (rc != pcmk_rc_ok) { crm_warn("%s notification of client %s failed: %s " QB_XS " id=%.8s rc=%d", type, pcmk__client_name(client), pcmk_rc_str(rc), client->id, rc); } else { crm_trace("Sent %s notification to client %s", type, pcmk__client_name(client)); } } } void do_stonith_async_timeout_update(const char *client_id, const char *call_id, int timeout) { pcmk__client_t *client = NULL; xmlNode *notify_data = NULL; if (!timeout || !call_id || !client_id) { return; } client = pcmk__find_client_by_id(client_id); if (!client) { return; } notify_data = pcmk__xe_create(NULL, PCMK__XE_ST_ASYNC_TIMEOUT_VALUE); crm_xml_add(notify_data, PCMK__XA_T, PCMK__VALUE_ST_ASYNC_TIMEOUT_VALUE); crm_xml_add(notify_data, PCMK__XA_ST_CALLID, call_id); crm_xml_add_int(notify_data, PCMK__XA_ST_TIMEOUT, timeout); crm_trace("timeout update is %d for client %s and call id %s", timeout, client_id, call_id); if (client) { pcmk__ipc_send_xml(client, 0, notify_data, crm_ipc_server_event); } pcmk__xml_free(notify_data); } /*! * \internal * \brief Notify relevant IPC clients of a fencing operation result * * \param[in] type Notification type * \param[in] result Result of fencing operation (assume success if NULL) * \param[in] data If not NULL, add to notification as call data */ void fenced_send_notification(const char *type, const pcmk__action_result_t *result, xmlNode *data) { /* TODO: Standardize the contents of data */ xmlNode *update_msg = pcmk__xe_create(NULL, PCMK__XE_NOTIFY); CRM_LOG_ASSERT(type != NULL); crm_xml_add(update_msg, PCMK__XA_T, PCMK__VALUE_ST_NOTIFY); crm_xml_add(update_msg, PCMK__XA_SUBT, type); crm_xml_add(update_msg, PCMK__XA_ST_OP, type); stonith__xe_set_result(update_msg, result); if (data != NULL) { xmlNode *wrapper = pcmk__xe_create(update_msg, PCMK__XE_ST_CALLDATA); pcmk__xml_copy(wrapper, data); } crm_trace("Notifying clients"); pcmk__foreach_ipc_client(stonith_notify_client, update_msg); pcmk__xml_free(update_msg); crm_trace("Notify complete"); } /*! * \internal * \brief Send notifications for a configuration change to subscribed clients * * \param[in] op Notification type (\c STONITH_OP_DEVICE_ADD, * \c STONITH_OP_DEVICE_DEL, \c STONITH_OP_LEVEL_ADD, or * \c STONITH_OP_LEVEL_DEL) * \param[in] result Operation result * \param[in] desc Description of what changed (either device ID or string * representation of level * ([])) */ void fenced_send_config_notification(const char *op, const pcmk__action_result_t *result, const char *desc) { xmlNode *notify_data = pcmk__xe_create(NULL, op); crm_xml_add(notify_data, PCMK__XA_ST_DEVICE_ID, desc); fenced_send_notification(op, result, notify_data); pcmk__xml_free(notify_data); } /*! * \internal * \brief Check whether a node does watchdog-fencing * * \param[in] node Name of node to check * * \return TRUE if node found in stonith_watchdog_targets * or stonith_watchdog_targets is empty indicating * all nodes are doing watchdog-fencing */ gboolean node_does_watchdog_fencing(const char *node) { return ((stonith_watchdog_targets == NULL) || pcmk__str_in_list(node, stonith_watchdog_targets, pcmk__str_casei)); } void stonith_shutdown(int nsig) { crm_info("Terminating with %d clients", pcmk__ipc_client_count()); stonith_shutdown_flag = TRUE; if (mainloop != NULL && g_main_loop_is_running(mainloop)) { g_main_loop_quit(mainloop); } } static void stonith_cleanup(void) { fenced_cib_cleanup(); if (ipcs) { qb_ipcs_destroy(ipcs); } pcmk__cluster_destroy_node_caches(); pcmk__client_cleanup(); free_stonith_remote_op_list(); free_topology_list(); free_device_list(); free_metadata_cache(); fenced_unregister_handlers(); free(stonith_our_uname); stonith_our_uname = NULL; } static gboolean stand_alone_cpg_cb(const gchar *option_name, const gchar *optarg, gpointer data, GError **error) { stand_alone = FALSE; options.no_cib_connect = true; return TRUE; } struct qb_ipcs_service_handlers ipc_callbacks = { .connection_accept = st_ipc_accept, .connection_created = NULL, .msg_process = st_ipc_dispatch, .connection_closed = st_ipc_closed, .connection_destroyed = st_ipc_destroy }; /*! * \internal * \brief Callback for peer status changes * * \param[in] type What changed * \param[in] node What peer had the change * \param[in] data Previous value of what changed */ static void st_peer_update_callback(enum crm_status_type type, crm_node_t * node, const void *data) { if ((type != crm_status_processes) && !pcmk_is_set(node->flags, crm_remote_node)) { /* * This is a hack until we can send to a nodeid and/or we fix node name lookups * These messages are ignored in stonith_peer_callback() */ xmlNode *query = pcmk__xe_create(NULL, PCMK__XE_STONITH_COMMAND); crm_xml_add(query, PCMK__XA_T, PCMK__VALUE_STONITH_NG); crm_xml_add(query, PCMK__XA_ST_OP, STONITH_OP_POKE); crm_debug("Broadcasting our uname because of node %u", node->id); pcmk__cluster_send_message(NULL, crm_msg_stonith_ng, query); pcmk__xml_free(query); } } /* @COMPAT Deprecated since 2.1.8. Use pcmk_list_fence_attrs() or * crm_resource --list-options=fencing instead of querying daemon metadata. */ static int fencer_metadata(void) { const char *name = "pacemaker-fenced"; const char *desc_short = N_("Instance attributes available for all " "\"stonith\"-class resources"); const char *desc_long = N_("Instance attributes available for all " "\"stonith\"-class resources and used by " - "Pacemaker's fence daemon, formerly known as " - "stonithd"); + "Pacemaker's fence daemon"); return pcmk__daemon_metadata(out, name, desc_short, desc_long, pcmk__opt_fencing); } static GOptionEntry entries[] = { { "stand-alone", 's', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &stand_alone, N_("Deprecated (will be removed in a future release)"), NULL }, { "stand-alone-w-cpg", 'c', G_OPTION_FLAG_NO_ARG, G_OPTION_ARG_CALLBACK, stand_alone_cpg_cb, N_("Intended for use in regression testing only"), NULL }, { "logfile", 'l', G_OPTION_FLAG_NONE, G_OPTION_ARG_FILENAME_ARRAY, &options.log_files, N_("Send logs to the additional named logfile"), NULL }, { NULL } }; static GOptionContext * build_arg_context(pcmk__common_args_t *args, GOptionGroup **group) { GOptionContext *context = NULL; context = pcmk__build_arg_context(args, "text (default), xml", group, NULL); pcmk__add_main_args(context, entries); return context; } int main(int argc, char **argv) { int rc = pcmk_rc_ok; pcmk_cluster_t *cluster = NULL; crm_ipc_t *old_instance = NULL; GError *error = NULL; GOptionGroup *output_group = NULL; pcmk__common_args_t *args = pcmk__new_common_args(SUMMARY); gchar **processed_args = pcmk__cmdline_preproc(argv, "l"); GOptionContext *context = build_arg_context(args, &output_group); crm_log_preinit(NULL, argc, argv); pcmk__register_formats(output_group, formats); if (!g_option_context_parse_strv(context, &processed_args, &error)) { exit_code = CRM_EX_USAGE; goto done; } rc = pcmk__output_new(&out, args->output_ty, args->output_dest, argv); if (rc != pcmk_rc_ok) { exit_code = CRM_EX_ERROR; g_set_error(&error, PCMK__EXITC_ERROR, exit_code, "Error creating output format %s: %s", args->output_ty, pcmk_rc_str(rc)); goto done; } if (args->version) { out->version(out, false); goto done; } if ((g_strv_length(processed_args) >= 2) && pcmk__str_eq(processed_args[1], "metadata", pcmk__str_none)) { rc = fencer_metadata(); if (rc != pcmk_rc_ok) { exit_code = CRM_EX_FATAL; g_set_error(&error, PCMK__EXITC_ERROR, exit_code, "Unable to display metadata: %s", pcmk_rc_str(rc)); } goto done; } // Open additional log files pcmk__add_logfiles(options.log_files, out); crm_log_init(NULL, LOG_INFO + args->verbosity, TRUE, (args->verbosity > 0), argc, argv, FALSE); crm_notice("Starting Pacemaker fencer"); old_instance = crm_ipc_new("stonith-ng", 0); if (old_instance == NULL) { /* crm_ipc_new() will have already logged an error message with * crm_err() */ exit_code = CRM_EX_FATAL; goto done; } if (pcmk__connect_generic_ipc(old_instance) == pcmk_rc_ok) { // IPC endpoint already up crm_ipc_close(old_instance); crm_ipc_destroy(old_instance); crm_err("pacemaker-fenced is already active, aborting startup"); goto done; } else { // Not up or not authentic, we'll proceed either way crm_ipc_destroy(old_instance); old_instance = NULL; } mainloop_add_signal(SIGTERM, stonith_shutdown); pcmk__cluster_init_node_caches(); rc = fenced_scheduler_init(); if (rc != pcmk_rc_ok) { exit_code = CRM_EX_FATAL; g_set_error(&error, PCMK__EXITC_ERROR, exit_code, "Error initializing scheduler data: %s", pcmk_rc_str(rc)); goto done; } cluster = pcmk_cluster_new(); if (!stand_alone) { #if SUPPORT_COROSYNC if (pcmk_get_cluster_layer() == pcmk_cluster_layer_corosync) { pcmk_cluster_set_destroy_fn(cluster, stonith_peer_cs_destroy); pcmk_cpg_set_deliver_fn(cluster, stonith_peer_ais_callback); pcmk_cpg_set_confchg_fn(cluster, pcmk__cpg_confchg_cb); } #endif // SUPPORT_COROSYNC pcmk__cluster_set_status_callback(&st_peer_update_callback); if (pcmk_cluster_connect(cluster) != pcmk_rc_ok) { exit_code = CRM_EX_FATAL; crm_crit("Cannot sign in to the cluster... terminating"); goto done; } pcmk__str_update(&stonith_our_uname, cluster->uname); if (!options.no_cib_connect) { setup_cib(); } } else { pcmk__str_update(&stonith_our_uname, "localhost"); crm_warn("Stand-alone mode is deprecated and will be removed " "in a future release"); } init_device_list(); init_topology_list(); pcmk__serve_fenced_ipc(&ipcs, &ipc_callbacks); // Create the mainloop and run it... mainloop = g_main_loop_new(NULL, FALSE); crm_notice("Pacemaker fencer successfully started and accepting connections"); g_main_loop_run(mainloop); done: g_strfreev(processed_args); pcmk__free_arg_context(context); g_strfreev(options.log_files); stonith_cleanup(); pcmk_cluster_free(cluster); fenced_scheduler_cleanup(); pcmk__output_and_clear_error(&error, out); if (out != NULL) { out->finish(out, exit_code, true, NULL); pcmk__output_free(out); } pcmk__unregister_formats(); crm_exit(exit_code); } diff --git a/doc/sphinx/shared/pacemaker-intro.rst b/doc/sphinx/shared/pacemaker-intro.rst index c8318ff156..dbea686b74 100644 --- a/doc/sphinx/shared/pacemaker-intro.rst +++ b/doc/sphinx/shared/pacemaker-intro.rst @@ -1,196 +1,172 @@ What Is Pacemaker? #################### Pacemaker is a high-availability *cluster resource manager* -- software that runs on a set of hosts (a *cluster* of *nodes*) in order to preserve integrity and minimize downtime of desired services (*resources*). [#]_ It is maintained by the `ClusterLabs `_ community. Pacemaker's key features include: * Detection of and recovery from node- and service-level failures * Ability to ensure data integrity by fencing faulty nodes * Support for one or more nodes per cluster * Support for multiple resource interface standards (anything that can be scripted can be clustered) * Support (but no requirement) for shared storage * Support for practically any redundancy configuration (active/passive, N+1, etc.) * Automatically replicated configuration that can be updated from any node * Ability to specify cluster-wide relationships between services, such as ordering, colocation, and anti-colocation * Support for advanced service types, such as *clones* (services that need to be active on multiple nodes), *promotable clones* (clones that can run in one of two roles), and containerized services * Unified, scriptable cluster management tools .. note:: **Fencing** *Fencing*, also known as *STONITH* (an acronym for Shoot The Other Node In The Head), is the ability to ensure that it is not possible for a node to be running a service. This is accomplished via *fence devices* such as intelligent power switches that cut power to the target, or intelligent network switches that cut the target's access to the local network. Pacemaker represents fence devices as a special class of resource. A cluster cannot safely recover from certain failure conditions, such as an unresponsive node, without fencing. Cluster Architecture ____________________ At a high level, a cluster can be viewed as having these parts (which together are often referred to as the *cluster stack*): * **Resources:** These are the reason for the cluster's being -- the services that need to be kept highly available. * **Resource agents:** These are scripts or operating system components that start, stop, and monitor resources, given a set of resource parameters. These provide a uniform interface between Pacemaker and the managed services. * **Fence agents:** These are scripts that execute node fencing actions, given a target and fence device parameters. * **Cluster membership layer:** This component provides reliable messaging, membership, and quorum information about the cluster. Currently, Pacemaker supports `Corosync `_ as this layer. * **Cluster resource manager:** Pacemaker provides the brain that processes and reacts to events that occur in the cluster. These events may include nodes joining or leaving the cluster; resource events caused by failures, maintenance, or scheduled activities; and other administrative actions. To achieve the desired availability, Pacemaker may start and stop resources and fence nodes. * **Cluster tools:** These provide an interface for users to interact with the cluster. Various command-line and graphical (GUI) interfaces are available. Most managed services are not, themselves, cluster-aware. However, many popular open-source cluster filesystems make use of a common *Distributed Lock Manager* (DLM), which makes direct use of Corosync for its messaging and membership capabilities and Pacemaker for the ability to fence nodes. .. image:: ../shared/images/pcmk-stack.png :alt: Example cluster stack :align: center Pacemaker Architecture ______________________ Pacemaker itself is composed of multiple daemons that work together: * ``pacemakerd`` * ``pacemaker-attrd`` * ``pacemaker-based`` * ``pacemaker-controld`` * ``pacemaker-execd`` * ``pacemaker-fenced`` * ``pacemaker-schedulerd`` .. image:: ../shared/images/pcmk-internals.png :alt: Pacemaker software components :align: center Pacemaker's main process (``pacemakerd``) spawns all the other daemons, and respawns them if they unexpectedly exit. The *Cluster Information Base* (CIB) is an `XML `_ representation of the cluster's configuration and the state of all nodes and resources. The *CIB manager* (``pacemaker-based``) keeps the CIB synchronized across the cluster, and handles requests to modify it. The *attribute manager* (``pacemaker-attrd``) maintains a database of attributes for all nodes, keeps it synchronized across the cluster, and handles requests to modify them. These attributes are usually recorded in the CIB. Given a snapshot of the CIB as input, the *scheduler* (``pacemaker-schedulerd``) determines what actions are necessary to achieve the desired state of the cluster. The *local executor* (``pacemaker-execd``) handles requests to execute resource agents on the local cluster node, and returns the result. The *fencer* (``pacemaker-fenced``) handles requests to fence nodes. Given a target node, the fencer decides which cluster node(s) should execute which fencing device(s), and calls the necessary fencing agents (either directly, or via requests to the fencer peers on other nodes), and returns the result. The *controller* (``pacemaker-controld``) is Pacemaker's coordinator, maintaining a consistent view of the cluster membership and orchestrating all the other components. Pacemaker centralizes cluster decision-making by electing one of the controller instances as the *Designated Controller* (*DC*). Should the elected DC process (or the node it is on) fail, a new one is quickly established. The DC responds to cluster events by taking a current snapshot of the CIB, feeding it to the scheduler, then asking the executors (either directly on the local node, or via requests to controller peers on other nodes) and the fencer to execute any necessary actions. -.. note:: **Old daemon names** - - The Pacemaker daemons were renamed in version 2.0. You may still find - references to the old names, especially in documentation targeted to - version 1.1. - - .. table:: - - +-----------------------+------------------------+ - | Old name | New name | - +=======================+========================+ - | ``attrd`` | ``pacemaker-attrd`` | - +-----------------------+------------------------+ - | ``cib`` | ``pacemaker-based`` | - +-----------------------+------------------------+ - | ``crmd`` | ``pacemaker-controld`` | - +-----------------------+------------------------+ - | ``lrmd`` | ``pacemaker-execd`` | - +-----------------------+------------------------+ - | ``stonithd`` | ``pacemaker-fenced`` | - +-----------------------+------------------------+ - | ``pacemaker_remoted`` | ``pacemaker-remoted`` | - +-----------------------+------------------------+ - Node Redundancy Designs _______________________ Pacemaker supports practically any `node redundancy configuration `_ including *Active/Active*, *Active/Passive*, *N+1*, *N+M*, *N-to-1*, and *N-to-N*. Active/passive clusters with two (or more) nodes using Pacemaker and `DRBD `_ are a cost-effective high-availability solution for many situations. One of the nodes provides the desired services, and if it fails, the other node takes over. .. image:: ../shared/images/pcmk-active-passive.png :alt: Active/Passive Redundancy :align: center Pacemaker also supports multiple nodes in a shared-failover design, reducing hardware costs by allowing several active/passive clusters to be combined and share a common backup node. .. image:: ../shared/images/pcmk-shared-failover.png :alt: Shared Failover :align: center When shared storage is available, every node can potentially be used for failover. Pacemaker can even run multiple copies of services to spread out the workload. This is sometimes called N-to-N redundancy. .. image:: ../shared/images/pcmk-active-active.png :alt: N to N Redundancy :align: center .. rubric:: Footnotes .. [#] *Cluster* is sometimes used in other contexts to refer to hosts grouped together for other purposes, such as high-performance computing (HPC), but Pacemaker is not intended for those purposes.