Changeset View
Changeset View
Standalone View
Standalone View
src/docs/user/cluster/cluster_databases.diviner
Show First 20 Lines • Show All 63 Lines • ▼ Show 20 Lines | |||||
Once you've configured this option, restart Phabricator for the changes to take | Once you've configured this option, restart Phabricator for the changes to take | ||||
effect, then continue to "Monitoring Replicas" to verify the configuration. | effect, then continue to "Monitoring Replicas" to verify the configuration. | ||||
Monitoring Replicas | Monitoring Replicas | ||||
=================== | =================== | ||||
You can monitor replicas in {nav Config > Cluster Databases}. This interface | You can monitor replicas in {nav Config > Database Servers}. This interface | ||||
shows you a quick overview of replicas and their health, and can detect some | shows you a quick overview of replicas and their health, and can detect some | ||||
common issues with replication. | common issues with replication. | ||||
The table on this page shows each database and current status. | The table on this page shows each database and current status. | ||||
NOTE: This page runs its diagnostics //from the web server that is serving the | NOTE: This page runs its diagnostics //from the web server that is serving the | ||||
request//. If you are recovering from a disaster, the view this page shows | request//. If you are recovering from a disaster, the view this page shows | ||||
may be partial or misleading, and two requests served by different servers may | may be partial or misleading, and two requests served by different servers may | ||||
▲ Show 20 Lines • Show All 60 Lines • ▼ Show 20 Lines | |||||
If things have been set up properly, Phabricator should degrade to a temporary | If things have been set up properly, Phabricator should degrade to a temporary | ||||
read-only mode immediately. After a brief period of unresponsiveness, it will | read-only mode immediately. After a brief period of unresponsiveness, it will | ||||
degrade further into a longer-term read-only mode. For details on how this | degrade further into a longer-term read-only mode. For details on how this | ||||
works interanlly, see "Unreachable Masters" below. | works interanlly, see "Unreachable Masters" below. | ||||
Once satisfied, turn the master back on. After a brief delay, Phabricator | Once satisfied, turn the master back on. After a brief delay, Phabricator | ||||
should recognize that the master is healthy again and recover fully. | should recognize that the master is healthy again and recover fully. | ||||
Throughout this process, the {nav Cluster Databases} console will show a | Throughout this process, the {nav Database Servers} console will show a | ||||
current view of the world from the perspective of the web server handling the | current view of the world from the perspective of the web server handling the | ||||
request. You can use it to monitor state. | request. You can use it to monitor state. | ||||
You can perform a more narrow test by enabling `cluster.read-only` in | You can perform a more narrow test by enabling `cluster.read-only` in | ||||
configuration. This will put Phabricator into read-only mode immediately | configuration. This will put Phabricator into read-only mode immediately | ||||
without turning off any databases. | without turning off any databases. | ||||
You can use this mode to understand which capabilities will and will not be | You can use this mode to understand which capabilities will and will not be | ||||
▲ Show 20 Lines • Show All 86 Lines • ▼ Show 20 Lines | |||||
of time. This mechanism is very similar to the health checks that most HTTP | of time. This mechanism is very similar to the health checks that most HTTP | ||||
load balancers perform against web servers. | load balancers perform against web servers. | ||||
If a database fails several health checks in a row, Phabricator will mark it as | If a database fails several health checks in a row, Phabricator will mark it as | ||||
unhealthy and stop sending all traffic (except for more health checks) to it. | unhealthy and stop sending all traffic (except for more health checks) to it. | ||||
This improves performance during a service interruption and reduces load on the | This improves performance during a service interruption and reduces load on the | ||||
master, which may help it recover from load problems. | master, which may help it recover from load problems. | ||||
You can monitor the status of health checks in the {nav Cluster Databases} | You can monitor the status of health checks in the {nav Database Servers} | ||||
console. The "Health" column shows how many checks have run recently and | console. The "Health" column shows how many checks have run recently and | ||||
how many have succeeded. | how many have succeeded. | ||||
Health checks run every 3 seconds, and 5 checks in a row must fail or succeed | Health checks run every 3 seconds, and 5 checks in a row must fail or succeed | ||||
before Phabricator marks the database as healthy or unhealthy, so it will | before Phabricator marks the database as healthy or unhealthy, so it will | ||||
generally take about 15 seconds for a database to change state after it goes | generally take about 15 seconds for a database to change state after it goes | ||||
down or comes up. | down or comes up. | ||||
▲ Show 20 Lines • Show All 50 Lines • Show Last 20 Lines |