minio/docs/metrics/prometheus/list.md
Harshavardhana eac4e4b279
honor replaced disk properly by updating globalLocalDrives (#19038)
globalLocalDrives seem to be not updated during the
HealFormat() leads to a requirement where the server
needs to be restarted for the healing to continue.
2024-02-12 13:00:20 -08:00

42 KiB

Cluster Metrics

MinIO collects the following metrics at the cluster level. Metrics may include one or more labels, such as the server that calculated that metric.

These metrics can be obtained from any MinIO server once per collection by using the following URL:

https://HOSTNAME:PORT/minio/v2/metrics/cluster

Replace HOSTNAME:PORT with the hostname of your MinIO deployment. For deployments behind a load balancer, use the load balancer hostname instead of a single node hostname.

Audit Metrics

Name Description
minio_audit_failed_messages Total number of messages that failed to send since start.
minio_audit_target_queue_length Number of unsent messages in queue for target.
minio_audit_total_messages Total number of messages sent since start.

Cluster Capacity Metrics

Name Description
minio_cluster_capacity_raw_free_bytes Total free capacity online in the cluster.
minio_cluster_capacity_raw_total_bytes Total capacity online in the cluster.
minio_cluster_capacity_usable_free_bytes Total free usable capacity online in the cluster.
minio_cluster_capacity_usable_total_bytes Total usable capacity online in the cluster.
minio_cluster_objects_size_distribution Distribution of object sizes across a cluster
minio_cluster_objects_version_distribution Distribution of object versions across a cluster
minio_cluster_usage_object_total Total number of objects in a cluster
minio_cluster_usage_total_bytes Total cluster usage in bytes
minio_cluster_usage_version_total Total number of versions (includes delete marker) in a cluster
minio_cluster_usage_deletemarker_total Total number of delete markers in a cluster
minio_cluster_usage_total_bytes Total cluster usage in bytes
minio_cluster_bucket_total Total number of buckets in the cluster

Cluster Drive Metrics

Name Description
minio_cluster_drive_offline_total Total drives offline in this cluster.
minio_cluster_drive_online_total Total drives online in this cluster.
minio_cluster_drive_total Total drives in this cluster.

Cluster ILM Metrics

Name Description
minio_cluster_ilm_transitioned_bytes Total bytes transitioned to a tier.
minio_cluster_ilm_transitioned_objects Total number of objects transitioned to a tier.
minio_cluster_ilm_transitioned_versions Total number of versions transitioned to a tier.

Cluster KMS Metrics

Name Description
minio_cluster_kms_online Reports whether the KMS is online (1) or offline (0).
minio_cluster_kms_request_error Number of KMS requests that failed due to some error. (HTTP 4xx status code).
minio_cluster_kms_request_failure Number of KMS requests that failed due to some internal failure. (HTTP 5xx status code).
minio_cluster_kms_request_success Number of KMS requests that succeeded.
minio_cluster_kms_uptime The time the KMS has been up and running in seconds.

Cluster Health Metrics

Name Description
minio_cluster_nodes_offline_total Total number of MinIO nodes offline.
minio_cluster_nodes_online_total Total number of MinIO nodes online.
minio_cluster_write_quorum Maximum write quorum across all pools and sets
minio_cluster_health_status Get current cluster health status

Cluster Replication Metrics

Metrics marked as Site Replication Only only populate on deployments with Site Replication configurations. For deployments with bucket or batch configurations, these metrics populate instead under the Bucket Metrics endpoint.

Name Description
minio_cluster_replication_current_active_workers Total number of active replication workers
minio_cluster_replication_average_active_workers Average number of active replication workers
minio_cluster_replication_max_active_workers Maximum number of active replication workers seen since server start
minio_cluster_replication_link_online Reports whether the replication link is online (1) or offline (0).
minio_cluster_replication_link_offline_duration_seconds Total duration of replication link being offline in seconds since last offline event
minio_cluster_replication_link_downtime_duration_seconds Total downtime of replication link in seconds since server start
minio_cluster_replication_average_link_latency_ms Average replication link latency in milliseconds
minio_cluster_replication_max_link_latency_ms Maximum replication link latency in milliseconds seen since server start
minio_cluster_replication_current_link_latency_ms Current replication link latency in milliseconds
minio_cluster_replication_current_transfer_rate Current replication transfer rate in bytes/sec
minio_cluster_replication_average_transfer_rate Average replication transfer rate in bytes/sec
minio_cluster_replication_max_transfer_rate Maximum replication transfer rate in bytes/sec seen since server start
minio_cluster_replication_last_minute_queued_count Total number of objects queued for replication in the last full minute
minio_cluster_replication_last_minute_queued_bytes Total number of bytes queued for replication in the last full minute
minio_cluster_replication_average_queued_count Average number of objects queued for replication since server start
minio_cluster_replication_average_queued_bytes Average number of bytes queued for replication since server start
minio_cluster_replication_max_queued_bytes Maximum number of bytes queued for replication seen since server start
minio_cluster_replication_max_queued_count Maximum number of objects queued for replication seen since server start
minio_cluster_replication_recent_backlog_count Total number of objects seen in replication backlog in the last 5 minutes
minio_cluster_replication_last_minute_failed_bytes Total number of bytes failed at least once to replicate in the last full minute.
minio_cluster_replication_last_minute_failed_count Total number of objects which failed replication in the last full minute.
minio_cluster_replication_last_hour_failed_bytes (Site Replication Only) Total number of bytes failed at least once to replicate in the last full hour.
minio_cluster_replication_last_hour_failed_count (Site Replication Only) Total number of objects which failed replication in the last full hour.
minio_cluster_replication_total_failed_bytes (Site Replication Only) Total number of bytes failed at least once to replicate since server start.
minio_cluster_replication_total_failed_count (Site Replication Only) Total number of objects which failed replication since server start.
minio_cluster_replication_received_bytes (Site Replication Only) Total number of bytes replicated to this cluster from another source cluster.
minio_cluster_replication_received_count (Site Replication Only) Total number of objects received by this cluster from another source cluster.
minio_cluster_replication_sent_bytes (Site Replication Only) Total number of bytes replicated to the target cluster.
minio_cluster_replication_sent_count (Site Replication Only) Total number of objects replicated to the target cluster.
minio_cluster_replication_credential_errors (Site Replication Only) Total number of replication credential errors since server start
minio_cluster_replication_proxied_get_requests_total (Site Replication Only)Number of GET requests proxied to replication target
minio_cluster_replication_proxied_head_requests_total (Site Replication Only)Number of HEAD requests proxied to replication target
minio_cluster_replication_proxied_delete_tagging_requests_total (Site Replication Only)Number of DELETE tagging requests proxied to replication target
minio_cluster_replication_proxied_get_tagging_requests_total (Site Replication Only)Number of GET tagging requests proxied to replication target
minio_cluster_replication_proxied_put_tagging_requests_total (Site Replication Only)Number of PUT tagging requests proxied to replication target
minio_cluster_replication_proxied_get_requests_failures (Site Replication Only)Number of failures in GET requests proxied to replication target
minio_cluster_replication_proxied_head_requests_failures (Site Replication Only)Number of failures in HEAD requests proxied to replication target
minio_cluster_replication_proxied_delete_tagging_requests_failures (Site Replication Only)Number of failures proxying DELETE tagging requests to replication target
minio_cluster_replication_proxied_get_tagging_requests_failures (Site Replication Only)Number of failures proxying GET tagging requests to replication target
minio_cluster_replication_proxied_put_tagging_requests_failures (Site Replication Only)Number of failures proxying PUT tagging requests to replication target

Healing Metrics

Name Description
minio_heal_objects_errors_total Objects for which healing failed in current self healing run.
minio_heal_objects_heal_total Objects healed in current self healing run.
minio_heal_objects_total Objects scanned in current self healing run.
minio_heal_time_last_activity_nano_seconds Time elapsed (in nano seconds) since last self healing activity.

Inter Node Metrics

Name Description
minio_inter_node_traffic_dial_avg_time Average time of internodes TCP dial calls.
minio_inter_node_traffic_dial_errors Total number of internode TCP dial timeouts and errors.
minio_inter_node_traffic_errors_total Total number of failed internode calls.
minio_inter_node_traffic_received_bytes Total number of bytes received from other peer nodes.
minio_inter_node_traffic_sent_bytes Total number of bytes sent to the other peer nodes.

Bucket Notification Metrics

Name Description
minio_notify_current_send_in_progress Number of concurrent async Send calls active to all targets (deprecated, please use 'minio_notify_target_current_send_in_progress' instead)
minio_notify_events_errors_total Events that were failed to be sent to the targets (deprecated, please use 'minio_notify_target_failed_events' instead)
minio_notify_events_sent_total Total number of events sent to the targets (deprecated, please use 'minio_notify_target_total_events' instead)
minio_notify_events_skipped_total Events that were skipped to be sent to the targets due to the in-memory queue being full
minio_notify_target_current_send_in_progress Number of concurrent async Send calls active to the target
minio_notify_target_queue_length Number of events currently staged in the queue_dir configured for the target.
minio_notify_target_total_events Total number of events sent (or) queued to the target

S3 API Request Metrics

Name Description
minio_s3_requests_4xx_errors_total Total number S3 requests with (4xx) errors.
minio_s3_requests_5xx_errors_total Total number S3 requests with (5xx) errors.
minio_s3_requests_canceled_total Total number S3 requests canceled by the client.
minio_s3_requests_errors_total Total number S3 requests with (4xx and 5xx) errors.
minio_s3_requests_incoming_total Volatile number of total incoming S3 requests.
minio_s3_requests_inflight_total Total number of S3 requests currently in flight.
minio_s3_requests_rejected_auth_total Total number S3 requests rejected for auth failure.
minio_s3_requests_rejected_header_total Total number S3 requests rejected for invalid header.
minio_s3_requests_rejected_invalid_total Total number S3 invalid requests.
minio_s3_requests_rejected_timestamp_total Total number S3 requests rejected for invalid timestamp.
minio_s3_requests_total Total number S3 requests.
minio_s3_requests_waiting_total Number of S3 requests in the waiting queue.
minio_s3_requests_ttfb_seconds_distribution Distribution of the time to first byte across API calls.
minio_s3_traffic_received_bytes Total number of s3 bytes received.
minio_s3_traffic_sent_bytes Total number of s3 bytes sent.

Software Metrics

Name Description
minio_software_commit_info Git commit hash for the MinIO release.
minio_software_version_info MinIO Release tag for the server.

Drive Metrics

Name Description
minio_node_drive_free_bytes Total storage available on a drive.
minio_node_drive_free_inodes Total free inodes.
minio_node_drive_latency_us Average last minute latency in µs for drive API storage operations.
minio_node_drive_offline_total Total drives offline in this node.
minio_node_drive_online_total Total drives online in this node.
minio_node_drive_total Total drives in this node.
minio_node_drive_total_bytes Total storage on a drive.
minio_node_drive_used_bytes Total storage used on a drive.
minio_node_drive_errors_timeout Total number of drive timeout errors since server start
minio_node_drive_errors_availability Total number of drive I/O errors, permission denied and timeouts since server start
minio_node_drive_io_waiting Total number I/O operations waiting on drive

Identity and Access Management (IAM) Metrics

Name Description
minio_node_iam_last_sync_duration_millis Last successful IAM data sync duration in milliseconds.
minio_node_iam_since_last_sync_millis Time (in milliseconds) since last successful IAM data sync.
minio_node_iam_sync_failures Number of failed IAM data syncs since server start.
minio_node_iam_sync_successes Number of successful IAM data syncs since server start.

Information Lifecycle Management (ILM) Metrics

Name Description
minio_node_ilm_expiry_pending_tasks Number of pending ILM expiry tasks in the queue.
minio_node_ilm_transition_active_tasks Number of active ILM transition tasks.
minio_node_ilm_transition_pending_tasks Number of pending ILM transition tasks in the queue.
minio_node_ilm_transition_missed_immediate_tasks Number of missed immediate ILM transition tasks.
minio_node_ilm_versions_scanned Total number of object versions checked for ilm actions since server start.
minio_node_ilm_action_count_delete_action Total action outcome of lifecycle checks since server start for deleting object
minio_node_ilm_action_count_delete_version_action Total action outcome of lifecycle checks since server start for deleting a version
minio_node_ilm_action_count_transition_action Total action outcome of lifecycle checks since server start for transition of an object
minio_node_ilm_action_count_transition_version_action Total action outcome of lifecycle checks since server start for transition of a particular object version
minio_node_ilm_action_count_delete_restored_action Total action outcome of lifecycle checks since server start for deletion of temporarily restored object
minio_node_ilm_action_count_delete_restored_version_action Total action outcome of lifecycle checks since server start for deletion of a temporarily restored version
minio_node_ilm_action_count_delete_all_versions_action Total action outcome of lifecycle checks since server start for deletion of all versions

Tier Metrics

Name Description
minio_node_tier_tier_ttlb_seconds_distribution Distribution of time to last byte for objects downloaded from warm tier
minio_node_tier_requests_success Number of requests to download object from warm tier that were successful
minio_node_tier_requests_failure Number of requests to download object from warm tier that were failure

System Metrics

Name Description
minio_node_file_descriptor_limit_total Limit on total number of open file descriptors for the MinIO Server process.
minio_node_file_descriptor_open_total Total number of open file descriptors by the MinIO Server process.
minio_node_go_routine_total Total number of go routines running.
minio_node_io_rchar_bytes Total bytes read by the process from the underlying storage system including cache, /proc/[pid]/io rchar.
minio_node_io_read_bytes Total bytes read by the process from the underlying storage system, /proc/[pid]/io read_bytes.
minio_node_io_wchar_bytes Total bytes written by the process to the underlying storage system including page cache, /proc/[pid]/io wchar.
minio_node_io_write_bytes Total bytes written by the process to the underlying storage system, /proc/[pid]/io write_bytes.
minio_node_process_cpu_total_seconds Total user and system CPU time spent in seconds.
minio_node_process_resident_memory_bytes Resident memory size in bytes.
minio_node_process_virtual_memory_bytes Virtual memory size in bytes.
minio_node_process_starttime_seconds Start time for MinIO process per node, time in seconds since Unix epoc.
minio_node_process_uptime_seconds Uptime for MinIO process per node in seconds.

Scanner Metrics

Name Description
minio_node_scanner_bucket_scans_finished Total number of bucket scans finished since server start.
minio_node_scanner_bucket_scans_started Total number of bucket scans started since server start.
minio_node_scanner_directories_scanned Total number of directories scanned since server start.
minio_node_scanner_objects_scanned Total number of unique objects scanned since server start.
minio_node_scanner_versions_scanned Total number of object versions scanned since server start.
minio_node_syscall_read_total Total read SysCalls to the kernel. /proc/[pid]/io syscr.
minio_node_syscall_write_total Total write SysCalls to the kernel. /proc/[pid]/io syscw.
minio_usage_last_activity_nano_seconds Time elapsed (in nano seconds) since last scan activity.

Bucket Metrics

MinIO collects the following metrics at the bucket level. Each metric includes the bucket label to identify the corresponding bucket. Metrics may include one or more additional labels, such as the server that calculated that metric.

These metrics can be obtained from any MinIO server once per collection by using the following URL:

https://HOSTNAME:PORT/minio/v2/metrics/bucket

Replace HOSTNAME:PORT with the hostname of your MinIO deployment. For deployments behind a load balancer, use the load balancer hostname instead of a single node hostname.

Distribution Metrics

Name Description
minio_bucket_objects_size_distribution Distribution of object sizes in the bucket, includes label for the bucket name.
minio_bucket_objects_version_distribution Distribution of object sizes in a bucket, by number of versions

Replication Metrics

These metrics only populate on deployments with Bucket Replication or Batch Replication configurations. For deployments with Site Replication configured, select metrics populate under the Cluster Metrics endpoint.

Name Description
minio_bucket_replication_last_minute_failed_bytes Total number of bytes failed at least once to replicate in the last full minute.
minio_bucket_replication_last_minute_failed_count Total number of objects which failed replication in the last full minute.
minio_bucket_replication_last_hour_failed_bytes Total number of bytes failed at least once to replicate in the last full hour.
minio_bucket_replication_last_hour_failed_count Total number of objects which failed replication in the last full hour.
minio_bucket_replication_total_failed_bytes Total number of bytes failed at least once to replicate since server start.
minio_bucket_replication_total_failed_count Total number of objects which failed replication since server start.
minio_bucket_replication_latency_ms Replication latency in milliseconds.
minio_bucket_replication_received_bytes Total number of bytes replicated to this bucket from another source bucket.
minio_bucket_replication_received_count Total number of objects received by this bucket from another source bucket.
minio_bucket_replication_sent_bytes Total number of bytes replicated to the target bucket.
minio_bucket_replication_sent_count Total number of objects replicated to the target bucket.
minio_bucket_replication_credential_errors Total number of replication credential errors since server start
minio_bucket_replication_proxied_get_requests_total Number of GET requests proxied to replication target
minio_bucket_replication_proxied_head_requests_total Number of HEAD requests proxied to replication target
minio_bucket_replication_proxied_delete_tagging_requests_total Number of DELETE tagging requests proxied to replication target
minio_bucket_replication_proxied_get_tagging_requests_total Number of GET tagging requests proxied to replication target
minio_bucket_replication_proxied_put_tagging_requests_total Number of PUT tagging requests proxied to replication target
minio_bucket_replication_proxied_get_requests_failures Number of failures in GET requests proxied to replication target
minio_bucket_replication_proxied_head_requests_failures Number of failures in HEAD requests proxied to replication target
minio_bucket_replication_proxied_delete_tagging_requests_failures Number of failures in DELETE tagging proxy requests to replication target
minio_bucket_replication_proxied_get_tagging_requests_failures Number of failures in GET tagging proxy requests to replication target
minio_bucket_replication_proxied_put_tagging_requests_failures Number of failures in PUT tagging proxy requests to replication target

Traffic Metrics

Name Description
minio_bucket_traffic_received_bytes Total number of S3 bytes received for this bucket.
minio_bucket_traffic_sent_bytes Total number of S3 bytes sent for this bucket.

Usage Metrics

Name Description
minio_bucket_usage_object_total Total number of objects.
minio_bucket_usage_version_total Total number of versions (includes delete marker)
minio_bucket_usage_deletemarker_total Total number of delete markers.
minio_bucket_usage_total_bytes Total bucket size in bytes.
minio_bucket_quota_total_bytes Total bucket quota size in bytes.

Requests Metrics

Name Description
minio_bucket_requests_4xx_errors_total Total number of S3 requests with (4xx) errors on a bucket.
minio_bucket_requests_5xx_errors_total Total number of S3 requests with (5xx) errors on a bucket.
minio_bucket_requests_inflight_total Total number of S3 requests currently in flight on a bucket.
minio_bucket_requests_total Total number of S3 requests on a bucket.
minio_bucket_requests_canceled_total Total number S3 requests canceled by the client.
minio_bucket_requests_ttfb_seconds_distribution Distribution of time to first byte across API calls per bucket.

Resource Metrics

MinIO collects the following resource metrics at the node level. Each metric includes the server label to identify the corresponding node. Metrics may include one or more additional labels, such as the drive path, interface name, etc.

These metrics can be obtained from any MinIO server once per collection by using the following URL:

https://HOSTNAME:PORT/minio/v2/metrics/resource

Replace HOSTNAME:PORT with the hostname of your MinIO deployment. For deployments behind a load balancer, use the load balancer hostname instead of a single node hostname.

Drive Resource Metrics

Name Description
minio_node_drive_total_bytes Total bytes on a drive.
minio_node_drive_used_bytes Used bytes on a drive.
minio_node_drive_total_inodes Total inodes on a drive.
minio_node_drive_used_inodes Total inodes used on a drive.
minio_node_drive_reads_per_sec Reads per second on a drive.
minio_node_drive_reads_kb_per_sec Kilobytes read per second on a drive.
minio_node_drive_reads_await Average time for read requests to be served on a drive.
minio_node_drive_writes_per_sec Writes per second on a drive.
minio_node_drive_writes_kb_per_sec Kilobytes written per second on a drive.
minio_node_drive_writes_await Average time for write requests to be served on a drive.
minio_node_drive_perc_util Percentage of time the disk was busy since uptime.

Network Interface Metrics

Name Description
minio_node_if_rx_bytes Bytes received on the interface in 60s.
minio_node_if_rx_bytes_avg Bytes received on the interface in 60s (avg) since uptime.
minio_node_if_rx_bytes_max Bytes received on the interface in 60s (max) since uptime.
minio_node_if_rx_errors Receive errors in 60s.
minio_node_if_rx_errors_avg Receive errors in 60s (avg).
minio_node_if_rx_errors_max Receive errors in 60s (max).
minio_node_if_tx_bytes Bytes transmitted in 60s.
minio_node_if_tx_bytes_avg Bytes transmitted in 60s (avg).
minio_node_if_tx_bytes_max Bytes transmitted in 60s (max).
minio_node_if_tx_errors Transmit errors in 60s.
minio_node_if_tx_errors_avg Transmit errors in 60s (avg).
minio_node_if_tx_errors_max Transmit errors in 60s (max).

CPU Metrics

Name Description
minio_node_cpu_avg_user CPU user time.
minio_node_cpu_avg_user_avg CPU user time (avg).
minio_node_cpu_avg_user_max CPU user time (max).
minio_node_cpu_avg_system CPU system time.
minio_node_cpu_avg_system_avg CPU system time (avg).
minio_node_cpu_avg_system_max CPU system time (max).
minio_node_cpu_avg_idle CPU idle time.
minio_node_cpu_avg_idle_avg CPU idle time (avg).
minio_node_cpu_avg_idle_max CPU idle time (max).
minio_node_cpu_avg_iowait CPU ioWait time.
minio_node_cpu_avg_iowait_avg CPU ioWait time (avg).
minio_node_cpu_avg_iowait_max CPU ioWait time (max).
minio_node_cpu_avg_nice CPU nice time.
minio_node_cpu_avg_nice_avg CPU nice time (avg).
minio_node_cpu_avg_nice_max CPU nice time (max).
minio_node_cpu_avg_steal CPU steam time.
minio_node_cpu_avg_steal_avg CPU steam time (avg).
minio_node_cpu_avg_steal_max CPU steam time (max).
minio_node_cpu_avg_load1 CPU load average 1min.
minio_node_cpu_avg_load1_avg CPU load average 1min (avg).
minio_node_cpu_avg_load1_max CPU load average 1min (max).
minio_node_cpu_avg_load1_perc CPU load average 1min (percentage).
minio_node_cpu_avg_load1_perc_avg CPU load average 1min (percentage) (avg).
minio_node_cpu_avg_load1_perc_max CPU load average 1min (percentage) (max).
minio_node_cpu_avg_load5 CPU load average 5min.
minio_node_cpu_avg_load5_avg CPU load average 5min (avg).
minio_node_cpu_avg_load5_max CPU load average 5min (max).
minio_node_cpu_avg_load5_perc CPU load average 5min (percentage).
minio_node_cpu_avg_load5_perc_avg CPU load average 5min (percentage) (avg).
minio_node_cpu_avg_load5_perc_max CPU load average 5min (percentage) (max).
minio_node_cpu_avg_load15 CPU load average 15min.
minio_node_cpu_avg_load15_avg CPU load average 15min (avg).
minio_node_cpu_avg_load15_max CPU load average 15min (max).
minio_node_cpu_avg_load15_perc CPU load average 15min (percentage).
minio_node_cpu_avg_load15_perc_avg CPU load average 15min (percentage) (avg).
minio_node_cpu_avg_load15_perc_max CPU load average 15min (percentage) (max).

Memory Metrics

Name Description
minio_node_mem_available Available memory on the node.
minio_node_mem_available_avg Available memory on the node (avg).
minio_node_mem_available_max Available memory on the node (max).
minio_node_mem_buffers Buffers memory on the node.
minio_node_mem_buffers_avg Buffers memory on the node (avg).
minio_node_mem_buffers_max Buffers memory on the node (max).
minio_node_mem_cache Cache memory on the node.
minio_node_mem_cache_avg Cache memory on the node (avg).
minio_node_mem_cache_max Cache memory on the node (max).
minio_node_mem_free Free memory on the node.
minio_node_mem_free_avg Free memory on the node (avg).
minio_node_mem_free_max Free memory on the node (max).
minio_node_mem_shared Shared memory on the node.
minio_node_mem_shared_avg Shared memory on the node (avg).
minio_node_mem_shared_max Shared memory on the node (max).
minio_node_mem_total Total memory on the node.
minio_node_mem_total_avg Total memory on the node (avg).
minio_node_mem_total_max Total memory on the node (max).
minio_node_mem_used Used memory on the node.
minio_node_mem_used_avg Used memory on the node (avg).
minio_node_mem_used_max Used memory on the node (max).
minio_node_mem_used_perc Used memory percentage on the node.
minio_node_mem_used_perc_avg Used memory percentage on the node (avg).
minio_node_mem_used_perc_max Used memory percentage on the node (max).