Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> c.d.o.server -> Re: Archiver question

Re: Archiver question

From: Joel Garry <joel-garry_at_home.com>
Date: 19 Apr 2005 15:32:26 -0700
Message-ID: <1113949946.550412.155090@f14g2000cwb.googlegroups.com>


It doesn't. It is smart enough to parallelize and get part of the log from one member and part from the other!

>From an old O7 faq:

"Having multiple members to a logfile group is also advisable. If there
are multiple members, all members in a group are used to perform the archive process. Assuming that there are three members, the first chunk
is read from one of the members and is being written to the archive while
reading a second chunk from second member, then a third chunk from third
member, then back to first and the process continues in round robin fashion.
If a corruption is found in one of the members, it is validated (read again)
and if the corruption still exists, reading from that member is stopped and the rest are used.

This is one of the big benefits of using multiple members instead of mirroring at o/s level. Oracle knows about the multiple members so it can
optimize on archiving, but it does not know about the mirrors. One other big
benefit with using multiple members is that a separate write is issued for
each member, so the odds of having a totally corrupted redo log is diminished (corruption written to one mirror will usually propagate over to
all other copies).
"

I have personally seen it figure out and overcome fairly severe corruption problems in recent versions, with no noticeable effect to users. But definitely check your alert log every day, there would have been a big effect one time if I hadn't noticed the messages about the failing hardware in time.

jg

--
@home.com is bogus.
ohnohackers!
http://www.signonsandiego.com/uniontrib/20050418/news_lz1b18hacker.html
Received on Tue Apr 19 2005 - 17:32:26 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US