Oracle document said very clearly. http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96653/log_tra= nsport.htm#1038566 To minimize data loss in the event of a primary database failure, you want = to copy data from the primary database to the standby database as it is bei= ng generated. You can choose to have either the log writer process or the a= rchiver process transmit redo logs to a destination. =2E... Choosing the LGWR attribute indicates that the log writer process (LGWR) wi= ll transmit redo data to the associated destination as it is generated. As = redo is generated for the primary database, it is also propagated to the st= andby system where the RFS process writes the redo to either a standby redo= log or to a standby archived redo log. On Wed, 5 Jan 2005 12:52:14 -0600=20 "Loughmiller, Greg" <greg.loughmiller@xxxxxxxxxxxx> wrote: > If I may ask a similar question, yet not exactly related to this thread.. > What are the advantages of using LGWR as compared to the ARCH process for > the transport mechanism of the redo data to the standby database? >=20 > Thanks > Greg > -----Original Message----- > From: Carel-Jan Engel [mailto:cjpengel.dbalert@xxxxxxxxx]=20 > Sent: Wednesday, January 05, 2005 11:55 AM > To: oracle-l@xxxxxxxxxxxxx > Subject: Re: About standby redo logs >=20 > Kamus, > Oracle documents that one needs at least the # of redo log groups on the > primary + 1 on the standby, when standby redologs are used. I never saw > a logswitch happen to another standby redologfile than the one > previously used, so your observation is quite normal, though somewhat > unexpected regarding the documented requirements. DG always seems to > reuse the same logfile. I guess it has to do with the speed of the ARCH > on the standby. I need to investigate this further if I get a chance on > a testsystem, before I can get more conclusive on this. >=20 > Because normally DG-configurations have real HA requirements (if not, > why was DG implemented), I tend to stay on the safe side and follow the > Oracle docs. It's a little bit CYA, I admit, so be it. >=20 > Best regards, >=20 > Carel-Jan Engel >=20 > =3D=3D=3D > If you think education is expensive, try ignorance. (Derek Bok) > =3D=3D=3D >=20 > Upcoming appearances:=20 >=20 > * Jan 27, 2005: London, UKOUG Unix SIG: Data Guard Best Practices= =20 > * Feb 9-10, 2005: Denver, RMOUG Training Days: Data Guard > Performance Issues=20 > * Mar 6-10, 2005: Dallas, Hotsos Symposium: Data Guard Performance > Issues >=20 >=20 > On Wed, 2005-01-05 at 15:33, Kamus wrote:=20 >=20 > > I create 4 standby redo log groups, and use LGWR in primary site to > > transfer redo data, all are good.=20 > > But when I query the V$STANDBY_LOG view, > > I found that only the status column of GROUP# 4(the first group of my > > standby redo logs) value is "ACTIVE" while all the others(5-7) are > > "UNASSIGNED". > > also, only GROUP# 4's sequence# is a value greate than 0 > > and THREAD# is 1, all others are 0 and 0. > >=20 > > Any explains. >=20 >=20 >=20 > =20 > *=20 >=20 >=20 > -- > //www.freelists.org/webpage/oracle-l >=20 >=20 > -- > //www.freelists.org/webpage/oracle-l --=20 Kamus <kamusis@xxxxxxxxx> =C4=C7=C3=B4=B6=E01G=B5=C4=D3=CA=CF=E4=A3=AC=CE=D2=C4=DC=D3=C3=C0=B4=B8=C9= =CA=B2=C3=B4:-) A Oracle8i & 9i Certified DBA from China -- //www.freelists.org/webpage/oracle-l