rsync read block size

[Matthias Schniedermeyer]

On 23.05.2009 17:32, Ming Zhang wrote:
> On Sat, May 23, 2009 at 10:25 AM, Matthias Schniedermeyer <ms at citd.de> wrote:
> > On 23.05.2009 08:44, Ming Zhang wrote:
> >> >
> >> > No. The block size is NEVER relevant for a copy via rsync, bits are bits
> >> > regardless of you copying them bit by bit or in larger groups.
> >> >
> >>
> >> please have a read
> >> http://www.oracle.com/technology/documentation/berkeley-db/db/ref/transapp/archival.html
> >> see the db page size issue when copy a online db.
> >
> > The meantioned utility to create the copy is NOT rsync, it's hotbackup.
> >
> > After the hotbackup is done, you can do whatever you like with the
> > created copy. In your case you want to transfer it to another computer.
> 
> that is what i meant.
> 
> i have DB that in hundreds of GBs. copy it out first by db_hotbackup
> take time and space. why not combine db_hotbackup and rsync to do 1
> step work?

I have to fold.

I don't seen any imediate possibility to combine hotbackup & rsync.

On the other hand the quiescent and device/filesystem snapshotting 
results in a rsyncable copy. On first glance db_checkpoint appears to 
provide the quiescent part by doing checkpoints.

Other than that, if you know how the database is structured you could 
write a script/program to syncronize the database content on a higher 
level than bit-copying the backing-store.

> >> > The man-page of db_hotbackup meantions (indirectly) that the backup is
> >> > without cooperation from the application and the database content may be
> >> > inconsistent. Not from the technical standpoint of BDB, but from the
> >> > high-level application standpoint. The application has to use
> >> > transactions correctly so that the database-content is consistent at any
> >> > point in time.
> >> >
> >> > In short: If your application does correcy transactions, hotbackup
> >> > appears to be a useable variant of the "snapshot"-db-backup type.
> >> >
> >>
> >> please not only read the man page of db_hotbackup, but also read the
> >> source code and the related BDB reference guide. then u will know that
> >> db_hotbackup do some db related work and then begin to copy file use
> >> posix read/write. and it read at multiple DB size.
> >
> > --
> >
> >
> >
> >
> > 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.
> >
> >

-- 




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.