DCC filling the filesystem

Gary Mills mills@cc.UManitoba.CA
Mon Nov 25 19:49:54 UTC 2002

On Thu, Nov 21, 2002 at 09:34:10PM -0700, Vernon Schryver wrote:
> > From: Gary Mills <mills@cc.UManitoba.CA>
> > I'm seeing regular complaints that dcc's filesystem is full, yet there's
> > a gigabyte of space left...
> >
> > Nov 21 21:55:21 electra ufs: [ID 213553 kern.notice] NOTICE: realloccg /var/dcc: file system full
> > ...
> That looks like a message from the kernel and not from any DCC
> code.  Thus, the UNIX kernel thinks the file system is full at
> least some of the time.

It turned out that this problem was caused by the Solaris UFS
settings.  The default for `newfs' is to create a filesystem with 8K
blocks and 1K fragments, but large writes only use blocks.  So, when
the UFS runs out of blocks, it reports `file system full', even though
there are lots of available fragments.  This problem commonly shows
up with a `squid' cache filesystem.

The quick fix is to umount the filesystem, and change optimization
from `time' to `space' with `tunefs'.  This enables large writes to
use fragments.  A better solution would be to recreate the filesystem
with `newfs', specifying a 4K fragment size to match the write size
that `dccd' uses.

-Gary Mills-    -Unix Support-    -U of M Academic Computing and Networking-

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