Re: 2.4.17 RAID-1 EXT3 reliable to hang....

From: Andrew Morton (
Date: Mon Jan 07 2002 - 03:49:30 EST

Oliver Paukstadt wrote:
> Heavy traffic on ext3 seems to cause short system freezes.

This could be due to disk request elevator latency and VM imbalance.
Your application has a page dropped due to the competing write activity,
and it takes ages to be restored, due to the write activity.
> Seems only to happen on 2 or more processor boxes.

In which case the above theory is wrong.
> I'm not deep into kernel nor ext3, but how is the journal flushed if
> full?

Nothing special, really - we just pump a stream of data out to disk.
While this is happening, other processes can still attach data to the
journal without getting blocked. Up to a point. Our handling of this
is a bit sudden at present. Some people have reported benefit from
radically decreasing the buffer flushtimes. See Daniel Robbins' article
at for this.
Yes, improvements are needed in this area. Not only in ext3.

You haven't really defined "freeze", but it's certainly different
from Matti's freeze.

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