Error Estimating RU Based on Load: 'resource_manager_resource_unit' is empty

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This topic has been translated from a Chinese forum by GPT and might contain errors.

Original topic: 根据负载情况估算ru时报错 ‘resource_manager_resource_unit’ is empty

| username: 裤衩儿飞上天

[TiDB Usage Environment] Test
[TiDB Version] 7.1.0
[Encountered Problem: Phenomenon and Impact]
Error when estimating RU based on load: ‘resource_manager_resource_unit’ is empty

Ignore the time in system monitoring, there is a timezone issue. Too lazy to change it.

TiDB root@10.18.13.224:tpcc> select sysdate()
+---------------------+
| sysdate()           |
+---------------------+
| 2023-06-12 09:06:56 |
+---------------------+
1 row in set
Time: 0.015s
TiDB root@10.18.13.224:tpcc> CALIBRATE RESOURCE START_TIME '2023-06-12 09:08:00' DURATION '10m'
(1105, "metrics 'resource_manager_resource_unit' is empty")
TiDB root@10.18.13.224:tpcc>
| username: 我是咖啡哥 | Original post link

I also encountered this error when executing :joy:
Is there any prerequisite operation…
I haven’t read the documentation yet.

| username: 裤衩儿飞上天 | Original post link

I haven’t found any relevant information yet, waiting for the experts’ suggestions~~~

| username: 我是咖啡哥 | Original post link

I can do it without any conditions.

| username: 裤衩儿飞上天 | Original post link

Without conditions, it is estimated based on hardware.
I can also do it without adding conditions.

| username: 裤衩儿飞上天 | Original post link

I misunderstood this part.
When estimating RU based on load, you should choose a past time period for estimation, rather than counting forward 10 minutes to 24 hours from now.
Additionally, the cluster needs to have a certain load during the selected estimation period.

| username: 有猫万事足 | Original post link

After using DM to execute a large table import, the calculated RU quantity based on load calibration is 10-20% higher than the estimate.

However, it is important to emphasize that during the execution of this large table import, 2 out of the 4 TiKV nodes experienced intermittent disconnections, fortunately at different times.

It seems that sticking to the estimated value is the safest approach. When your system pressure is high enough to calibrate the RUs, it is often close to the pressure limit, making it prone to issues.

The extra 10-20% RUs are not as important compared to stability.

| username: system | Original post link

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