Re: redo log sync time

One point to bear in mind is that the 'redo log synch' time is NOT the redo log write time - it is (usually) the time between a foreground process sending a message to LGWR to do a log sync, and the time that the process can continue, so it includes dead time for process switches and all the other overheads associated with mulit-tasking.

(Steve Adams' book on Internal Waits, etc. is the best source of information for this sort of thing - see his website at www.ixora.com.au)

--
Jonathan Lewis
Yet another Oracle-related web site:  http://www.jlcomp.demon.co.uk

Practical Oracle 8i:  Building Efficient Databases

Publishers:  Addison-Wesley
See a first review at:
http://www.ixora.com.au/resources/index.htm#practical_8i
More reviews at: http://www.jlcomp.demon.co.uk/book_rev.html



Andreas Goldammer wrote in message
<3a5eaec3$0$8788$73bec562_at_personalnews.de.uu.net>...


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>I have tuned I/O and removed the contention on the disk drives and

>I am still wondering why the logsync time is the same as on the

>old box.

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>My tuning actions:

>    - a faster box (about double speed)

>    - split the I/O's to the SSA (use two adapters on separate bus)

>    - install faster disk drives

>    - increase the SSA speed from 20 to 40

>    - remove the AIX mirror from the log filesystems (avoid MWC)

>    - allocate the logs on separate disks (with no other FS on)

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>These actions were taken and I can see a performance improvment;

>e.g.  The database response times have decreased significant,

>       The creation of a 2GB datafile on the old box took 15 min

>       whereas the new one finishes in 4 min.

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>Can anybody tell me about logfile sync and hardware in other OLTP's ?

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