未验证 提交 4621cd29 编写于 作者: S Sean Ely 提交者: GitHub

docs: grammar: cluster operation

Small grammar updates to cluster operations.
上级 51660873
...@@ -3,7 +3,7 @@ sidebar_label: Operation ...@@ -3,7 +3,7 @@ sidebar_label: Operation
title: Manage DNODEs title: Manage DNODEs
--- ---
It has been introduced that how to deploy and start a cluster from scratch. Once a cluster is ready, the dnode status in the cluster can be shown at any time, new dnode can be added to scale out the cluster, an existing dnode can be removed, even load balance can be performed manually.\ The previous section [Deployment](/cluster/deploy) introduced how to deploy and start a cluster from scratch. Once a cluster is ready, the dnode status in the cluster can be shown at any time, new dnode can be added to scale out the cluster, an existing dnode can be removed, even load balance can be performed manually.
:::note :::note
All the commands to be introduced in this chapter need to be run through TDengine CLI, sometimes it's necessary to use root privilege. All the commands to be introduced in this chapter need to be run through TDengine CLI, sometimes it's necessary to use root privilege.
...@@ -12,7 +12,7 @@ All the commands to be introduced in this chapter need to be run through TDengin ...@@ -12,7 +12,7 @@ All the commands to be introduced in this chapter need to be run through TDengin
## Show DNODEs ## Show DNODEs
below command can be executed in TDengine CLI `taos` to list all dnodes in the cluster, including ID, end point (fqdn:port), status (ready, offline), number of vnodes, number of free vnodes, etc. It's suggested to execute this command to check after adding or removing a dnode. The below command can be executed in TDengine CLI `taos` to list all dnodes in the cluster, including ID, end point (fqdn:port), status (ready, offline), number of vnodes, number of free vnodes, etc. It's suggested to execute this command to check after adding or removing a dnode.
```sql ```sql
SHOW DNODES; SHOW DNODES;
...@@ -39,7 +39,7 @@ USE SOME_DATABASE; ...@@ -39,7 +39,7 @@ USE SOME_DATABASE;
SHOW VGROUPS; SHOW VGROUPS;
``` ```
The example output is as below: The example output is below:
``` ```
taos> show dnodes; taos> show dnodes;
...@@ -87,7 +87,7 @@ taos> show dnodes; ...@@ -87,7 +87,7 @@ taos> show dnodes;
Query OK, 2 row(s) in set (0.001017s) Query OK, 2 row(s) in set (0.001017s)
``` ```
It can be seen that the status of the new dnode is "offline", once the dnode is started and connects the firstEp of the cluster, execute the command again and get below example output, from which it can be seen that two dnodes are both in "ready" status. It can be seen that the status of the new dnode is "offline", once the dnode is started and connects the firstEp of the cluster, execute the command again and get the example output below, from which it can be seen that two dnodes are both in "ready" status.
``` ```
taos> show dnodes; taos> show dnodes;
...@@ -100,7 +100,7 @@ Query OK, 2 row(s) in set (0.001316s) ...@@ -100,7 +100,7 @@ Query OK, 2 row(s) in set (0.001316s)
## Drop DNODE ## Drop DNODE
Launch TDengine CLI `taos` and execute the command below to drop or remove a dnode from the cluster. In the command, `dnodeId` can be gotten from `show dnodes`. Launch TDengine CLI `taos` and execute the command below to drop or remove a dnode from the cluster. In the command, you can get `dnodeId` from `show dnodes`.
```sql ```sql
DROP DNODE "fqdn:port"; DROP DNODE "fqdn:port";
...@@ -112,7 +112,7 @@ or ...@@ -112,7 +112,7 @@ or
DROP DNODE dnodeId; DROP DNODE dnodeId;
``` ```
The example output is as below: The example output is below:
``` ```
taos> show dnodes; taos> show dnodes;
...@@ -139,7 +139,7 @@ In the above example, when `show dnodes` is executed the first time, two dnodes ...@@ -139,7 +139,7 @@ In the above example, when `show dnodes` is executed the first time, two dnodes
- Once a dnode is dropped, it can't rejoin the cluster. To rejoin, the dnode needs to deployed again after cleaning up the data directory. Normally, before dropping a dnode, the data belonging to the dnode needs to be migrated to other place. - Once a dnode is dropped, it can't rejoin the cluster. To rejoin, the dnode needs to deployed again after cleaning up the data directory. Normally, before dropping a dnode, the data belonging to the dnode needs to be migrated to other place.
- Please be noted that `drop dnode` is different from stopping `taosd` process. `drop dnode` just removes the dnode out of TDengine cluster. Only after a dnode is dropped, can the corresponding `taosd` process be stopped. - Please be noted that `drop dnode` is different from stopping `taosd` process. `drop dnode` just removes the dnode out of TDengine cluster. Only after a dnode is dropped, can the corresponding `taosd` process be stopped.
- Once a dnode is dropped, other dnodes in the cluster will be notified of the drop and will not accept the request from the dropped dnode. - Once a dnode is dropped, other dnodes in the cluster will be notified of the drop and will not accept the request from the dropped dnode.
- dnodeID is allocated automatically and can't be interfered manually. dnodeID is generated in ascending order without duplication. - dnodeID is allocated automatically and can't be manually modified. dnodeID is generated in ascending order without duplication.
::: :::
...@@ -155,7 +155,7 @@ ALTER DNODE <source-dnodeId> BALANCE "VNODE:<vgId>-DNODE:<dest-dnodeId>"; ...@@ -155,7 +155,7 @@ ALTER DNODE <source-dnodeId> BALANCE "VNODE:<vgId>-DNODE:<dest-dnodeId>";
In the above command, `source-dnodeId` is the original dnodeId where the vnode resides, `dest-dnodeId` specifies the target dnode. vgId (vgroup ID) can be shown by `SHOW VGROUPS `. In the above command, `source-dnodeId` is the original dnodeId where the vnode resides, `dest-dnodeId` specifies the target dnode. vgId (vgroup ID) can be shown by `SHOW VGROUPS `.
Firstly `show vgroups` is executed to show the vgroup distribution. First `show vgroups` is executed to show the vgroup distribution.
``` ```
taos> show vgroups; taos> show vgroups;
...@@ -172,7 +172,7 @@ taos> show vgroups; ...@@ -172,7 +172,7 @@ taos> show vgroups;
Query OK, 8 row(s) in set (0.001314s) Query OK, 8 row(s) in set (0.001314s)
``` ```
It can be seen that there are 5 vgroups in dnode 3 and 3 vgroups in node 1, now we want to move vgId 18 from dnode 3 to dnode 1. Execute below command in `taos` It can be seen that there are 5 vgroups in dnode 3 and 3 vgroups in node 1, now we want to move vgId 18 from dnode 3 to dnode 1. Execute the below command in `taos`
``` ```
taos> alter dnode 3 balance "vnode:18-dnode:1"; taos> alter dnode 3 balance "vnode:18-dnode:1";
...@@ -207,7 +207,7 @@ It can be seen from above output that vgId 18 has been moved from dnode 3 to dno ...@@ -207,7 +207,7 @@ It can be seen from above output that vgId 18 has been moved from dnode 3 to dno
:::note :::note
- Manual load balancing can only be performed when the automatic load balancing is disabled, i.e. `balance` is set to 0. - Manual load balancing can only be performed when the automatic load balancing is disabled, i.e. `balance` is set to 0.
- Only vnode in normal state, i.e. master or slave, can be moved. vnode can't moved when its in status offline, unsynced or syncing. - Only a vnode in normal state, i.e. master or slave, can be moved. vnode can't be moved when its in status offline, unsynced or syncing.
- Before moving a vnode, it's necessary to make sure the target dnode has enough resources: CPU, memory and disk. - Before moving a vnode, it's necessary to make sure the target dnode has enough resources: CPU, memory and disk.
::: :::
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