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Re: journal tuning

On Wed, Aug 21, 2002 at 09:55:57AM +0200, Mindaugas Riauba wrote:

>   From what I read I understood that for typical operations
> data=ordered is prefered. For the cases when there are many writes
> not appending to files data=journal is the choice. And if I want to
> get the most performance or in case where program is doing journaling
> itself (Oracle) - data=writeback is the answer.

My rationale is this:

I use data=journal for a Postfix queue. How much data can come in via
the 100MBit backbone in 5s (the commit interval):

100MBit/s * 5s = 500MBit

The journal should be about that size.
>   But what about the size of the journal? The only clues I found is
> that data=journal journal should be the size ~ 5 seconds worth of
> writes to the disk. And that other types journals are typically
> sized enough by default.

One could argue that the journal must be 5s * max transfer rate/s big.
How do I estimate that?

Ralf Hildebrandt (Im Auftrag des Referat V A)   Ralf Hildebrandt charite de
Charite Campus Virchow-Klinikum                 Tel.  +49 (0)30-450 570-155
Referat V A - Kommunikationsnetze -             Fax.  +49 (0)30-450 570-916
Sysadmins don't go to hell; we're already doing our time in purgatory. 

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