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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Standby Database
Richard,
Comments inline..
-----Original Message-----
Sent: Thursday, November 29, 2001 6:40 AM
To: Multiple recipients of list ORACLE-L
This sounds good, but I have a couple of questions. How do you guarantee
that
you won't lose any committed transactions? I mean, the C program could lag
behind
the LGWR since it's only reading it without lock and it's copying the online
redo over
to a remote machine. So for a busy database, the LGWR will just keep
writing and the
C program won't be able to keep up with it's pace.
The external program uses X$KCCCP as a feedback for copying process. X$KCCCP
will have
the current log block (Disk RBA) and this will have the change vectors for
last commit. So you
copy the change vectors/ redo records immediately as soon as it is written.
If LGWR can keep
writing the files means why can't your C program copy the files?
Are you copying the whole partially filled online redo? or just the
difference
since the last commit?
Difference from last copy.. (last commit )
Did I miss understand it? Please advise.
>>> kaygopal_at_yahoo.com 11/29/01 12:40AM >>>
If you want to Zero data loss in standby you can copy the online redo logs thru an external C program. You can copy the online redo log files when the LGWR is writing to it.
The program should read the log files without locking. You can use the fixed
table X$KCCLE and X$KCCCP to find how much is written in the log files.
The partially filled log file can be shipped to the standby location and
you can
open the standby database with the new control file created with NORESETLOGs
.
In this way you have a graceful fail over in the standby database and no
committed
Transaction is lost in the standby database
Does this sound good?
Best Regards,
K Gopalakrishnan
Bangalore, INDIA
-----Original Message-----
Sent: Wednesday, November 28, 2001 4:16 PM
To: Multiple recipients of list ORACLE-L
I am also facing the same problem. All these disadvantages in 8i standby DB have been taken care of in oracle 9i version. The other solution could be to buy an expensive Veritas Cluster server/Database edition.
Thanks,
-- Janardhana babu
-----Original Message-----
Sent: Wednesday, November 28, 2001 3:35 PM
To: Multiple recipients of list ORACLE-L
Quick question. Is it a fair statement to say that using Oracle's hot standby database allows you recoverability up to the last archive log, but would NOT recover to the latest redo log (prior to a log switch). In other words, the potential to lose transactions is very high if you depend on this for failover (not good for e-commerce type databases). Would it be possible to somehow mirror redo logs across to the failover server and apply them when activating the standby database, or is the only real solution clustering or something like DoubleTake?
Am I making sense?
Thanks,
Ed
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Author: Ed
INET: mrclark_at_xnet.com
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Author: K Gopalakrishnan
INET: kaygopal_at_yahoo.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Liststo: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing). Received on Thu Nov 29 2001 - 22:15:25 CST
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