Geen cache-versie.
Caching uitgeschakeld. Standaardinstelling voor deze pagina:ingeschakeld (code DEF204)Als het scherm te langzaam is, kunt u de gebruikersmodus uitschakelen om de cacheversie te bekijken.
Rechercher dans le manuel MySQL
17.3.1.3 Backing Up a Master or Slave by Making It Read Only
It is possible to back up either master or slave servers in a
replication setup by acquiring a global read lock and
manipulating the read_only
system variable to change the read-only state of the server to
be backed up:
Make the server read-only, so that it processes only retrievals and blocks updates.
Perform the backup.
Change the server back to its normal read/write state.
The instructions in this section place the server to be backed up in a state that is safe for backup methods that get the data from the server, such as mysqldump (see Section 4.5.4, “mysqldump — A Database Backup Program”). You should not attempt to use these instructions to make a binary backup by copying files directly because the server may still have modified data cached in memory and not flushed to disk.
The following instructions describe how to do this for a master server and for a slave server. For both scenarios discussed here, suppose that you have the following replication setup:
A master server M1
A slave server S1 that has M1 as its master
A client C1 connected to M1
A client C2 connected to S1
In either scenario, the statements to acquire the global read
lock and manipulate the
read_only variable are
performed on the server to be backed up and do not propagate to
any slaves of that server.
Scenario 1: Backup with a Read-Only Master
Put the master M1 in a read-only state by executing these statements on it:
While M1 is in a read-only state, the following properties are true:
Requests for updates sent by C1 to M1 will block because the server is in read-only mode.
Requests for query results sent by C1 to M1 will succeed.
Making a backup on M1 is safe.
Making a backup on S1 is not safe. This server is still running, and might be processing the binary log or update requests coming from client C2.
While M1 is read only, perform the backup. For example, you can use mysqldump.
After the backup operation on M1 completes, restore M1 to its normal operational state by executing these statements:
Although performing the backup on M1 is safe (as far as the backup is concerned), it is not optimal for performance because clients of M1 are blocked from executing updates.
This strategy applies to backing up a master server in a replication setup, but can also be used for a single server in a nonreplication setting.
Scenario 2: Backup with a Read-Only Slave
Put the slave S1 in a read-only state by executing these statements on it:
While S1 is in a read-only state, the following properties are true:
The master M1 will continue to operate, so making a backup on the master is not safe.
The slave S1 is stopped, so making a backup on the slave S1 is safe.
These properties provide the basis for a popular backup scenario: Having one slave busy performing a backup for a while is not a problem because it does not affect the entire network, and the system is still running during the backup. In particular, clients can still perform updates on the master server, which remains unaffected by backup activity on the slave.
While S1 is read only, perform the backup. For example, you can use mysqldump.
After the backup operation on S1 completes, restore S1 to its normal operational state by executing these statements:
After the slave is restored to normal operation, it again synchronizes to the master by catching up with any outstanding updates from the binary log of the master.
Nederlandse vertaling
U hebt gevraagd om deze site in het Nederlands te bezoeken. Voor nu wordt alleen de interface vertaald, maar nog niet alle inhoud.Als je me wilt helpen met vertalingen, is je bijdrage welkom. Het enige dat u hoeft te doen, is u op de site registreren en mij een bericht sturen waarin u wordt gevraagd om u toe te voegen aan de groep vertalers, zodat u de gewenste pagina's kunt vertalen. Een link onderaan elke vertaalde pagina geeft aan dat u de vertaler bent en heeft een link naar uw profiel.
Bij voorbaat dank.
Document heeft de 26/06/2006 gemaakt, de laatste keer de 26/10/2018 gewijzigd
Bron van het afgedrukte document:https://www.gaudry.be/nl/mysql-rf-replication-solutions-backups-read-only.html
De infobrol is een persoonlijke site waarvan de inhoud uitsluitend mijn verantwoordelijkheid is. De tekst is beschikbaar onder CreativeCommons-licentie (BY-NC-SA). Meer info op de gebruiksvoorwaarden en de auteur.
Referenties
Deze verwijzingen en links verwijzen naar documenten die geraadpleegd zijn tijdens het schrijven van deze pagina, of die aanvullende informatie kunnen geven, maar de auteurs van deze bronnen kunnen niet verantwoordelijk worden gehouden voor de inhoud van deze pagina.
De auteur Deze site is als enige verantwoordelijk voor de manier waarop de verschillende concepten, en de vrijheden die met de referentiewerken worden genomen, hier worden gepresenteerd. Vergeet niet dat u meerdere broninformatie moet doorgeven om het risico op fouten te verkleinen.
