Ed,List Since we Enable log_checkpoint_interval to a Very High Value , Qs Would READs for Data of Tables Also NOT Occur from the Online Redo Logfiles ?
NOTE Oracle version 8.1.7.2 Thanks > -----Original Message----- > From: Edward Shevtsov [SMTP:[EMAIL PROTECTED]] > Sent: Thursday, November 15, 2001 7:16 PM > To: Multiple recipients of list ORACLE-L > Subject: Re: Configuring for Online Redo Logfiles > > Hi Vivek, > > If I didn't worry about data safety I would choose redo logs on > dedicated > single disks. > The reason is that usually the speed of LGWR's writes is more > important for > performance compared with speed of ARCH's reads. > > Regards, > Ed > > > > Conor,List > > > > 1) Mirrored Redo Logs WRITES may have an Overhead of 15-20 % > > EXCERPT from Gaja's Doc "One of the common myths with mirroring, is > that > > it takes "twice as long" to write.But in many performance > measurements > > and benchmarks, the overhead has been observed to be around 15-20%." > > > > 2) Mirrored Redo Logs READS are Twice as Fast than NON-Mirrored > > > > Considering BOTH the Above to POINTS , FINALLY Strictly w.r.t. > > performance of Online Redo Logs , WITHOUT any Consideration for Data > > Safety , Which would be Better ? > > > > Thanks > > > > > > > -----Original Message----- > > > From: Connor McDonald [SMTP:[EMAIL PROTECTED]] > > > Sent: Thursday, November 15, 2001 3:15 PM > > > To: Multiple recipients of list ORACLE-L > > > Subject: Re: Configuring for Online Redo Logfiles > > > > > > An unmirrored disk will run faster (with respect to > > > writes) than a mirrored one (not twice as fast since > > > writes on a mirror are typically done in parallel). > > > Then again - now you've got an unmirrored redo > > > log...not a good idea. To get around this, you'd need > > > to duplex it through Oracle - which pretty much gets > > > you back to a "mirrored" redo log. > > > > > > hth > > > connor > > > > > > --- VIVEK_SHARMA <[EMAIL PROTECTED]> wrote: > > > > EXCERPT from "Implementing Raid On Oracle Systems" > > > > by Gaja Krishna > > > > Vaidyanatha, Quest Software Inc. :- > > > > "RAID 1 - Ideal for online and archived redo logs, > > > > Leaves the write-head > > > > at the location of the last write. On most systems, > > > > you will need 3 > > > > volumes for the online redo logs (for 3 groups) and > > > > 1 volume for the > > > > archived redo logs. If your database is in > > > > NOARCHIVELOG mode, you > > > > probably can get away with a single RAID 1 volume > > > > for your redo-logs. > > > > However, for databases in ARCHIVELOG mode you will > > > > need to further > > > > separate you" > > > > Qs. Puttting an Online Redo log on a RAID1 Volume ( > > > > Volume Containing 1 > > > > Disk Mirrored to Another Disk ) versus putting the > > > > Same Online redo file > > > > on a Single Disk (NON-Mirrored) , which would give > > > > Better performance , > > > > Why ? > > > > -- > > > -- > Please see the official ORACLE-L FAQ: http://www.orafaq.com > -- > Author: Edward Shevtsov > INET: [EMAIL PROTECTED] > > Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 > San Diego, California -- Public Internet access / Mailing Lists > -------------------------------------------------------------------- > To REMOVE yourself from this mailing list, send an E-Mail message > to: [EMAIL PROTECTED] (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). -- Please see the official ORACLE-L FAQ: http://www.orafaq.com -- Author: VIVEK_SHARMA INET: [EMAIL PROTECTED] Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051 San Diego, California -- Public Internet access / Mailing Lists -------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (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).
