Den 2012-01-12 09:38 skrev reynaldi81 s�h�r:

>
> Hi all,
>
> Is it safe to backup database using gbak, when there are users
> accessing and making transaction on the database? Is it better to use
> gbak or nbackup for this case?
>
>
> __,_.

Both gbak an nbackup can be run "anytime".

Gbak runs as a readonly transaction, just as any other transaction. It
MAY however trigger extensive garbage collection, which MAY cause a
somewhat sluggish system. Try and you will find out. :-)

Nbackup locks the database file for writes during the backup process.
During that time, the system can keep running as usual, but all updates
are written to a separate file. When the database file is unlocked after
completed backup, the secondary file is merged back into the main file.

Gbak is better in that it actually reads all data structures, so in
addition to a backup it essentially also verifies the database
integrity. Nbackup doesn't - instead it works at the page level without
really inspecting the data contents inside those pages.

Nbackup MAY be faster, especially for >0 level backups, though.

You'll have to decide for yourself which backup tool is best for you. If
you decide to use nbackup, I'd recommend you to also verify the database
integrity regularly, since nbackup doesn't do that.

Kjell

--
--------------------------------------
Kjell Rilbe
DataDIA AB
E-post: kjell@...
Telefon: 08-761 06 55
Mobil: 0733-44 24 64



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