The device exception in the cluster (the addition and deletion of the exception OSD) can result in inconsistent data between the various copies of the PG, and data recovery is required so that all replicas are in a consistent state.First, the OSD
Crush Algorithm1, the purpose of crushOptimize allocation data, efficiently reorganize data, flexibly constrain object copy placement, maximize data security when hardware fails2. ProcessIn the Ceph architecture, the Ceph client is directly read and
This example describes the database operations classes available in MYSQL,MSSQL,PG three databases, and you can easily change the type of your database as long as you make any changes. Share it for your reference. The specific analysis is as follows:
-Function Manifest Index:-Open: Opening database connection line:71-Close: Closes the database connection line:107-SELECTDB: Select Database line:129-Query: Create queries line:151-Dataseek: Move record pointer line:175-FieldName: Get field name
The Ceph Crush algorithm (controlled Replication under Scalablehashing) is an algorithm based on data distribution and replication for random control.Basic principle:Storage devices typically support stripe to increase storage system throughput and
Calculation formula for PG:
Calculation formula for the entire cluster PG
The calculation formula for PG in each pool:
Total PGs = (TOTAL_NUMBER_OF_OSD *)/Max_replication_count/pool_count
The result of the settlement is taken up to the
Calculating the PG Count formula for a single poolPoolpgcount= ((TARGETPGSPEROSD)? ( Osdnumber)? (datapercent)) /poolsizeParameter introduction
name
Description
Notes
Pool PG Count
Number of PG
Export command- - 5432 - -- inserts-t human_info > D:\human_info_backup.sql testdbCommand descriptionPg_dump: is the backup command that comes with the PG database, and in the bin directory, all execution must be performed in the bin directory.- H:
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A lot of content is online search information, I just tidy up, there are missing places, welcome to add
First Use tool (ORA2PG) to automatically
The PG database is the PostgreSQL database.A few days ago in a Java project, the data table exception hangs for the PG database after running the Java program. And it appears on a computer, reloading the database is useless, the other computers can
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