[linux] MySQL zalohy

[Ing. Ján ONDREJ]

Je to lepsie ako nic, ale v uplne konzistentnom stave nemusi byt.
Existuju totis rozne cache, napr. samotnej databazy alebo diskove, takze by
si v skripte mal aspon na cas vytvorenia snapshotu (zvycajne <1s) stopnut
mysqld, napr.:
  service mysqld stop
  lvcreate -s ...
  service mysqld start

Sice budes mat minimalny vypadok, ale konzistentnost udajov stoji za to.

Ak by si to robit nechcel, tak este mas moznost urobit aspon "sync" tesne
pred samotnym lvcreate -s, ten bude vhodny aj ked mysqld stopnes.

Ja som skor uvazoval nad 100% konzistentnou DB s uplne nulovym vypadkom a to
tym, ze urobim nie len snapshot diskovej particie, ale aj pamate virtualneho
pocitaca. Musis mat ale virtualne nie len diskove oddiely, ale aj samotny
pocitac.

		SAL

On Sun, May 17, 2009 at 06:47:35PM +0100, Martin Simovic wrote:
> 
> 
> On Sun, 2009-05-17 at 03:46 +0200, warezman wrote:
> > Cafte,
> > 
> > na MySQL zalohy pouzivam mysqldump nasledovne:
> > 
> > mysqldump -R -q –single-transaction --user=root --password=pass
> > database db | gzip >  file.gz
> > 
> > Akurat, ze na serveroch s novym jadrom mi po spusteni príkazu apache
> > ide velmi pomaly [nacitanie fora 20s], na starsom debiane to fungovalo
> > v poriadku. Problem by vyriesilo nastavenie priority mysqldumpu, ale
> > neviem ako na to. Dalsie riesenie je kopirovat mysql priamo z
> > /var/lib/mysql ale neni to najlepsie riesenie.
> > 
> 
> mozes aj priamo kopirovat /var/lib/mysql ale len ak si schopny najprv
> spravit snapshot filesystemu. ja mam napr. vsetko na lvm a riesim to
> skriptom
> 
> #!/bin/bash
> /bin/echo -n "Generating a snapshot of runnig database at " ; date +%H:%
> M:%S
> /sbin/lvcreate -s -n snap -L 1G system/var || exit 1 
> /bin/echo -n "Mounting frozen database partition on /backup " ; date +%
> H:%M:%S
> /bin/mount -v -t ext3 /dev/mapper/system-snap /backup
> /bin/echo -n "Cleaning up destination directory /database " ; date +%H:%
> M:%S
> /bin/rm -rf /database/*
> /bin/echo -n "Copying new database files to /database " ; date +%H:%M:%S
> /bin/cp -a /backup/lib/mysql /database
> /bin/echo -n "Unmounting a database snapshot " ; date +%H:%M:%S
> /bin/umount -v /backup
> /bin/echo -n "Deleting database snapshot " ; date +%H:%M:%S
> /sbin/lvremove -f system/snap
> /bin/echo -n "Done " ; date +%H:%M:%S
> 
> toto mi bezi z cronu kazdu noc. nasledne je robeny backup celeho
> filesystemu, keby som potreboval restornut databazu tak ju najdem
> konzistentnu v /database directory.
> 
> 
> > S pozdravom
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