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List:       ext3-users
Subject:    Re: Info before I try this
From:       "Stephen C. Tweedie" <sct () redhat ! com>
Date:       2000-11-21 11:29:45
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Hi,

On Tue, Nov 21, 2000 at 09:46:05AM +0000, Nigel Metheringham wrote:
> 
> sct@redhat.com said:
> > Yep, the release notes should cover all of that.  Use "mke3fs -j" to
> > set journal size, and the default is 15MB. 
> 
> Care to comment on factors affecting the best size of journal?

If it is too small, there are two impacts.  First, the writeback
caching is more limited, so bursty write traffic becomes synchronous
sooner.  Secondly, you limit the amount of reording that can be done
and the ability of the filesystem to merge writebacks together,
increasing seeks.

The penalties of a large journal are that the journal can occupy more
pinned physical memory, and recovery takes longer.  The memory
consumption is probably the most significant won for most users.

Cheers,
 Stephen

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