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/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.cluster.routing.allocation.decider;
import java.util.Set;
import com.carrotsearch.hppc.cursors.ObjectCursor;
import org.elasticsearch.cluster.ClusterInfo;
import org.elasticsearch.cluster.DiskUsage;
import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.routing.IndexShardRoutingTable;
import org.elasticsearch.cluster.routing.RecoverySource;
import org.elasticsearch.cluster.routing.RoutingNode;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.ShardRoutingState;
import org.elasticsearch.cluster.routing.allocation.DiskThresholdSettings;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.common.Strings;
import org.elasticsearch.common.collect.ImmutableOpenMap;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.settings.Settings;
import org.elasticsearch.common.unit.ByteSizeValue;
import org.elasticsearch.index.Index;
import org.elasticsearch.index.shard.ShardId;
import static org.elasticsearch.cluster.routing.allocation.DiskThresholdSettings.CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING;
import static org.elasticsearch.cluster.routing.allocation.DiskThresholdSettings.CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK_SETTING;
/**
* The {@link DiskThresholdDecider} checks that the node a shard is potentially
* being allocated to has enough disk space.
*
* It has three configurable settings, all of which can be changed dynamically:
*
* cluster.routing.allocation.disk.watermark.low is the low disk
* watermark. New shards will not allocated to a node with usage higher than this,
* although this watermark may be passed by allocating a shard. It defaults to
* 0.85 (85.0%).
*
* cluster.routing.allocation.disk.watermark.high is the high disk
* watermark. If a node has usage higher than this, shards are not allowed to
* remain on the node. In addition, if allocating a shard to a node causes the
* node to pass this watermark, it will not be allowed. It defaults to
* 0.90 (90.0%).
*
* Both watermark settings are expressed in terms of used disk percentage, or
* exact byte values for free space (like "500mb")
*
* cluster.routing.allocation.disk.threshold_enabled is used to
* enable or disable this decider. It defaults to false (disabled).
*/
public class DiskThresholdDecider extends AllocationDecider {
public static final String NAME = "disk_threshold";
private final DiskThresholdSettings diskThresholdSettings;
public DiskThresholdDecider(Settings settings, ClusterSettings clusterSettings) {
super(settings);
this.diskThresholdSettings = new DiskThresholdSettings(settings, clusterSettings);
}
/**
* Returns the size of all shards that are currently being relocated to
* the node, but may not be finished transferring yet.
*
* If subtractShardsMovingAway is true then the size of shards moving away is subtracted from the total size of all shards
*/
static long sizeOfRelocatingShards(RoutingNode node, RoutingAllocation allocation,
boolean subtractShardsMovingAway, String dataPath) {
ClusterInfo clusterInfo = allocation.clusterInfo();
long totalSize = 0;
for (ShardRouting routing : node.shardsWithState(ShardRoutingState.RELOCATING, ShardRoutingState.INITIALIZING)) {
String actualPath = clusterInfo.getDataPath(routing);
if (dataPath.equals(actualPath)) {
if (routing.initializing() && routing.relocatingNodeId() != null) {
totalSize += getExpectedShardSize(routing, allocation, 0);
} else if (subtractShardsMovingAway && routing.relocating()) {
totalSize -= getExpectedShardSize(routing, allocation, 0);
}
}
}
return totalSize;
}
@Override
public Decision canAllocate(ShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) {
ClusterInfo clusterInfo = allocation.clusterInfo();
ImmutableOpenMap usages = clusterInfo.getNodeMostAvailableDiskUsages();
final Decision decision = earlyTerminate(allocation, usages);
if (decision != null) {
return decision;
}
final double usedDiskThresholdLow = 100.0 - diskThresholdSettings.getFreeDiskThresholdLow();
final double usedDiskThresholdHigh = 100.0 - diskThresholdSettings.getFreeDiskThresholdHigh();
// subtractLeavingShards is passed as false here, because they still use disk space, and therefore should we should be extra careful
// and take the size into account
DiskUsage usage = getDiskUsage(node, allocation, usages, false);
// First, check that the node currently over the low watermark
double freeDiskPercentage = usage.getFreeDiskAsPercentage();
// Cache the used disk percentage for displaying disk percentages consistent with documentation
double usedDiskPercentage = usage.getUsedDiskAsPercentage();
long freeBytes = usage.getFreeBytes();
if (logger.isTraceEnabled()) {
logger.trace("node [{}] has {}% used disk", node.nodeId(), usedDiskPercentage);
}
// flag that determines whether the low threshold checks below can be skipped. We use this for a primary shard that is freshly
// allocated and empty.
boolean skipLowTresholdChecks = shardRouting.primary() &&
shardRouting.active() == false && shardRouting.recoverySource().getType() == RecoverySource.Type.EMPTY_STORE;
// checks for exact byte comparisons
if (freeBytes < diskThresholdSettings.getFreeBytesThresholdLow().getBytes()) {
if (skipLowTresholdChecks == false) {
if (logger.isDebugEnabled()) {
logger.debug("less than the required {} free bytes threshold ({} bytes free) on node {}, preventing allocation",
diskThresholdSettings.getFreeBytesThresholdLow(), freeBytes, node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the node is above the low watermark cluster setting [%s=%s], having less than the minimum required [%s] free " +
"space, actual free: [%s]",
CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getLowWatermarkRaw(),
diskThresholdSettings.getFreeBytesThresholdLow(), new ByteSizeValue(freeBytes));
} else if (freeBytes > diskThresholdSettings.getFreeBytesThresholdHigh().getBytes()) {
// Allow the shard to be allocated because it is primary that
// has never been allocated if it's under the high watermark
if (logger.isDebugEnabled()) {
logger.debug("less than the required {} free bytes threshold ({} bytes free) on node {}, " +
"but allowing allocation because primary has never been allocated",
diskThresholdSettings.getFreeBytesThresholdLow(), freeBytes, node.nodeId());
}
return allocation.decision(Decision.YES, NAME,
"the node is above the low watermark, but less than the high watermark, and this primary shard has " +
"never been allocated before");
} else {
// Even though the primary has never been allocated, the node is
// above the high watermark, so don't allow allocating the shard
if (logger.isDebugEnabled()) {
logger.debug("less than the required {} free bytes threshold ({} bytes free) on node {}, " +
"preventing allocation even though primary has never been allocated",
diskThresholdSettings.getFreeBytesThresholdHigh(), freeBytes, node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the node is above the high watermark cluster setting [%s=%s], having less than the minimum required [%s] free " +
"space, actual free: [%s]",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(),
diskThresholdSettings.getFreeBytesThresholdHigh(), new ByteSizeValue(freeBytes));
}
}
// checks for percentage comparisons
if (freeDiskPercentage < diskThresholdSettings.getFreeDiskThresholdLow()) {
// If the shard is a replica or is a non-empty primary, check the low threshold
if (skipLowTresholdChecks == false) {
if (logger.isDebugEnabled()) {
logger.debug("more than the allowed {} used disk threshold ({} used) on node [{}], preventing allocation",
Strings.format1Decimals(usedDiskThresholdLow, "%"),
Strings.format1Decimals(usedDiskPercentage, "%"), node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the node is above the low watermark cluster setting [%s=%s], using more disk space than the maximum allowed " +
"[%s%%], actual free: [%s%%]",
CLUSTER_ROUTING_ALLOCATION_LOW_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getLowWatermarkRaw(), usedDiskThresholdLow, freeDiskPercentage);
} else if (freeDiskPercentage > diskThresholdSettings.getFreeDiskThresholdHigh()) {
// Allow the shard to be allocated because it is primary that
// has never been allocated if it's under the high watermark
if (logger.isDebugEnabled()) {
logger.debug("more than the allowed {} used disk threshold ({} used) on node [{}], " +
"but allowing allocation because primary has never been allocated",
Strings.format1Decimals(usedDiskThresholdLow, "%"),
Strings.format1Decimals(usedDiskPercentage, "%"), node.nodeId());
}
return allocation.decision(Decision.YES, NAME,
"the node is above the low watermark, but less than the high watermark, and this primary shard has " +
"never been allocated before");
} else {
// Even though the primary has never been allocated, the node is
// above the high watermark, so don't allow allocating the shard
if (logger.isDebugEnabled()) {
logger.debug("less than the required {} free bytes threshold ({} bytes free) on node {}, " +
"preventing allocation even though primary has never been allocated",
Strings.format1Decimals(diskThresholdSettings.getFreeDiskThresholdHigh(), "%"),
Strings.format1Decimals(freeDiskPercentage, "%"), node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the node is above the high watermark cluster setting [%s=%s], using more disk space than the maximum allowed " +
"[%s%%], actual free: [%s%%]",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(), usedDiskThresholdHigh, freeDiskPercentage);
}
}
// Secondly, check that allocating the shard to this node doesn't put it above the high watermark
final long shardSize = getExpectedShardSize(shardRouting, allocation, 0);
double freeSpaceAfterShard = freeDiskPercentageAfterShardAssigned(usage, shardSize);
long freeBytesAfterShard = freeBytes - shardSize;
if (freeBytesAfterShard < diskThresholdSettings.getFreeBytesThresholdHigh().getBytes()) {
logger.warn("after allocating, node [{}] would have less than the required " +
"{} free bytes threshold ({} bytes free), preventing allocation",
node.nodeId(), diskThresholdSettings.getFreeBytesThresholdHigh(), freeBytesAfterShard);
return allocation.decision(Decision.NO, NAME,
"allocating the shard to this node will bring the node above the high watermark cluster setting [%s=%s] " +
"and cause it to have less than the minimum required [%s] of free space (free bytes after shard added: [%s])",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(),
diskThresholdSettings.getFreeBytesThresholdHigh(), new ByteSizeValue(freeBytesAfterShard));
}
if (freeSpaceAfterShard < diskThresholdSettings.getFreeDiskThresholdHigh()) {
logger.warn("after allocating, node [{}] would have more than the allowed " +
"{} free disk threshold ({} free), preventing allocation",
node.nodeId(), Strings.format1Decimals(diskThresholdSettings.getFreeDiskThresholdHigh(), "%"),
Strings.format1Decimals(freeSpaceAfterShard, "%"));
return allocation.decision(Decision.NO, NAME,
"allocating the shard to this node will bring the node above the high watermark cluster setting [%s=%s] " +
"and cause it to use more disk space than the maximum allowed [%s%%] (free space after shard added: [%s%%])",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(), usedDiskThresholdHigh, freeSpaceAfterShard);
}
return allocation.decision(Decision.YES, NAME,
"enough disk for shard on node, free: [%s], shard size: [%s], free after allocating shard: [%s]",
new ByteSizeValue(freeBytes),
new ByteSizeValue(shardSize),
new ByteSizeValue(freeBytesAfterShard));
}
@Override
public Decision canRemain(ShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) {
if (shardRouting.currentNodeId().equals(node.nodeId()) == false) {
throw new IllegalArgumentException("Shard [" + shardRouting + "] is not allocated on node: [" + node.nodeId() + "]");
}
final ClusterInfo clusterInfo = allocation.clusterInfo();
final ImmutableOpenMap usages = clusterInfo.getNodeLeastAvailableDiskUsages();
final Decision decision = earlyTerminate(allocation, usages);
if (decision != null) {
return decision;
}
// subtractLeavingShards is passed as true here, since this is only for shards remaining, we will *eventually* have enough disk
// since shards are moving away. No new shards will be incoming since in canAllocate we pass false for this check.
final DiskUsage usage = getDiskUsage(node, allocation, usages, true);
final String dataPath = clusterInfo.getDataPath(shardRouting);
// If this node is already above the high threshold, the shard cannot remain (get it off!)
final double freeDiskPercentage = usage.getFreeDiskAsPercentage();
final long freeBytes = usage.getFreeBytes();
if (logger.isTraceEnabled()) {
logger.trace("node [{}] has {}% free disk ({} bytes)", node.nodeId(), freeDiskPercentage, freeBytes);
}
if (dataPath == null || usage.getPath().equals(dataPath) == false) {
return allocation.decision(Decision.YES, NAME,
"this shard is not allocated on the most utilized disk and can remain");
}
if (freeBytes < diskThresholdSettings.getFreeBytesThresholdHigh().getBytes()) {
if (logger.isDebugEnabled()) {
logger.debug("less than the required {} free bytes threshold ({} bytes free) on node {}, shard cannot remain",
diskThresholdSettings.getFreeBytesThresholdHigh(), freeBytes, node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the shard cannot remain on this node because it is above the high watermark cluster setting [%s=%s] " +
"and there is less than the required [%s] free space on node, actual free: [%s]",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(),
diskThresholdSettings.getFreeBytesThresholdHigh(), new ByteSizeValue(freeBytes));
}
if (freeDiskPercentage < diskThresholdSettings.getFreeDiskThresholdHigh()) {
if (logger.isDebugEnabled()) {
logger.debug("less than the required {}% free disk threshold ({}% free) on node {}, shard cannot remain",
diskThresholdSettings.getFreeDiskThresholdHigh(), freeDiskPercentage, node.nodeId());
}
return allocation.decision(Decision.NO, NAME,
"the shard cannot remain on this node because it is above the high watermark cluster setting [%s=%s] " +
"and there is less than the required [%s%%] free disk on node, actual free: [%s%%]",
CLUSTER_ROUTING_ALLOCATION_HIGH_DISK_WATERMARK_SETTING.getKey(),
diskThresholdSettings.getHighWatermarkRaw(),
diskThresholdSettings.getFreeDiskThresholdHigh(), freeDiskPercentage);
}
return allocation.decision(Decision.YES, NAME,
"there is enough disk on this node for the shard to remain, free: [%s]", new ByteSizeValue(freeBytes));
}
private DiskUsage getDiskUsage(RoutingNode node, RoutingAllocation allocation,
ImmutableOpenMap usages, boolean subtractLeavingShards) {
DiskUsage usage = usages.get(node.nodeId());
if (usage == null) {
// If there is no usage, and we have other nodes in the cluster,
// use the average usage for all nodes as the usage for this node
usage = averageUsage(node, usages);
if (logger.isDebugEnabled()) {
logger.debug("unable to determine disk usage for {}, defaulting to average across nodes [{} total] [{} free] [{}% free]",
node.nodeId(), usage.getTotalBytes(), usage.getFreeBytes(), usage.getFreeDiskAsPercentage());
}
}
if (diskThresholdSettings.includeRelocations()) {
long relocatingShardsSize = sizeOfRelocatingShards(node, allocation, subtractLeavingShards, usage.getPath());
DiskUsage usageIncludingRelocations = new DiskUsage(node.nodeId(), node.node().getName(), usage.getPath(),
usage.getTotalBytes(), usage.getFreeBytes() - relocatingShardsSize);
if (logger.isTraceEnabled()) {
logger.trace("usage without relocations: {}", usage);
logger.trace("usage with relocations: [{} bytes] {}", relocatingShardsSize, usageIncludingRelocations);
}
usage = usageIncludingRelocations;
}
return usage;
}
/**
* Returns a {@link DiskUsage} for the {@link RoutingNode} using the
* average usage of other nodes in the disk usage map.
* @param node Node to return an averaged DiskUsage object for
* @param usages Map of nodeId to DiskUsage for all known nodes
* @return DiskUsage representing given node using the average disk usage
*/
DiskUsage averageUsage(RoutingNode node, ImmutableOpenMap usages) {
if (usages.size() == 0) {
return new DiskUsage(node.nodeId(), node.node().getName(), "_na_", 0, 0);
}
long totalBytes = 0;
long freeBytes = 0;
for (ObjectCursor du : usages.values()) {
totalBytes += du.value.getTotalBytes();
freeBytes += du.value.getFreeBytes();
}
return new DiskUsage(node.nodeId(), node.node().getName(), "_na_", totalBytes / usages.size(), freeBytes / usages.size());
}
/**
* Given the DiskUsage for a node and the size of the shard, return the
* percentage of free disk if the shard were to be allocated to the node.
* @param usage A DiskUsage for the node to have space computed for
* @param shardSize Size in bytes of the shard
* @return Percentage of free space after the shard is assigned to the node
*/
double freeDiskPercentageAfterShardAssigned(DiskUsage usage, Long shardSize) {
shardSize = (shardSize == null) ? 0 : shardSize;
DiskUsage newUsage = new DiskUsage(usage.getNodeId(), usage.getNodeName(), usage.getPath(),
usage.getTotalBytes(), usage.getFreeBytes() - shardSize);
return newUsage.getFreeDiskAsPercentage();
}
private Decision earlyTerminate(RoutingAllocation allocation, ImmutableOpenMap usages) {
// Always allow allocation if the decider is disabled
if (diskThresholdSettings.isEnabled() == false) {
return allocation.decision(Decision.YES, NAME, "the disk threshold decider is disabled");
}
// Allow allocation regardless if only a single data node is available
if (allocation.nodes().getDataNodes().size() <= 1) {
if (logger.isTraceEnabled()) {
logger.trace("only a single data node is present, allowing allocation");
}
return allocation.decision(Decision.YES, NAME, "there is only a single data node present");
}
// Fail open there is no info available
final ClusterInfo clusterInfo = allocation.clusterInfo();
if (clusterInfo == null) {
if (logger.isTraceEnabled()) {
logger.trace("cluster info unavailable for disk threshold decider, allowing allocation.");
}
return allocation.decision(Decision.YES, NAME, "the cluster info is unavailable");
}
// Fail open if there are no disk usages available
if (usages.isEmpty()) {
if (logger.isTraceEnabled()) {
logger.trace("unable to determine disk usages for disk-aware allocation, allowing allocation");
}
return allocation.decision(Decision.YES, NAME, "disk usages are unavailable");
}
return null;
}
/**
* Returns the expected shard size for the given shard or the default value provided if not enough information are available
* to estimate the shards size.
*/
public static long getExpectedShardSize(ShardRouting shard, RoutingAllocation allocation, long defaultValue) {
final IndexMetaData metaData = allocation.metaData().getIndexSafe(shard.index());
final ClusterInfo info = allocation.clusterInfo();
if (metaData.getResizeSourceIndex() != null && shard.active() == false &&
shard.recoverySource().getType() == RecoverySource.Type.LOCAL_SHARDS) {
// in the shrink index case we sum up the source index shards since we basically make a copy of the shard in
// the worst case
long targetShardSize = 0;
final Index mergeSourceIndex = metaData.getResizeSourceIndex();
final IndexMetaData sourceIndexMeta = allocation.metaData().index(mergeSourceIndex);
if (sourceIndexMeta != null) {
final Set shardIds = IndexMetaData.selectRecoverFromShards(shard.id(),
sourceIndexMeta, metaData.getNumberOfShards());
for (IndexShardRoutingTable shardRoutingTable : allocation.routingTable().index(mergeSourceIndex.getName())) {
if (shardIds.contains(shardRoutingTable.shardId())) {
targetShardSize += info.getShardSize(shardRoutingTable.primaryShard(), 0);
}
}
}
return targetShardSize == 0 ? defaultValue : targetShardSize;
} else {
return info.getShardSize(shard, defaultValue);
}
}
}
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