Re: Archiver question

Hi, Joel,

Michel Cadot and I did some research. See http://www.dba-village.com/village/dvp_forum.OpenThread?ThreadIdA=12100 (you may need to register to view it and it's free)

Basically, in Metalink threads 448634.999 and 370101.995, Melissa Holman questioned about that "round robin" mechanism in normal cases. The article you quoted, as well as other sources (such as Rama Velpuri's book, p.75 of Oracle8 ed.), may be outdated and not corrected. To prove for yourself, a simple ARC0 process trace on UNIX/Linux is sufficient. Michel's test shows that although the logfile header of all members is read (generally 512 bytes but 1K on HPUX), the file body i.e. actual redo entries are read from the first member only.

Incidentally, since it's proved (pending more tests coming in) that only one member is read, the classical debate on one member mirrored by hardware versus multiple members configured by Oracle slightly tilts toward the former (still assuming DBAs are careful of rm command on OS), because the latter no longer has that specific benefit claimed in Note:45042.1.

Yong Huang
yong321ATyahoo.com Received on Wed Apr 20 2005 - 14:38:08 CDT