rsync read block size

Matthias Schniedermeyer ms at citd.de
Fri May 22 21:37:36 GMT 2009


On 22.05.2009 16:25, Ming Zhang wrote:
> Hi All
> 
> We want to use rsync to backup a live Berkley db to a remote site. BDB
> has a requirement that read has to be in the unit of db page size. So
> wonder how could we make sure that rsync can follow that? If we need
> to change the code, where we should begin to look at? Thanks!

The read block size is irrelevant, the problem you have is consistency.

If you want a working copy of a database (and this goes for any 
database) you have to quiescent the database first. Otherwise the 
file(s) in the filesystem may not be in a consistent state.

Also you must either quiescent the database the WHOLE TIME you back it 
up, or you must use some form of snapshoting for the filesystem and then 
backup the snapshot. (quiescent -> Snapshot -> unquiescent)
(Or use some other database depend backup procedure)

How you quiescent a database is about as database dependend as it can 
get and personally i don't know how the procedure is for a BDB.
But i guess(!) you need cooperation from the program(s) working with the 
db.



Googling: backup berkeley db
Appear to give answers, but i only took a quick glance.



Bis denn

-- 
Real Programmers consider "what you see is what you get" to be just as 
bad a concept in Text Editors as it is in women. No, the Real Programmer
wants a "you asked for it, you got it" text editor -- complicated, 
cryptic, powerful, unforgiving, dangerous.



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