Subject: Re: Which file-system is good for power down?
To: None <>
From: John Nemeth <>
List: netbsd-users
Date: 12/30/2007 00:39:35
On May 21,  2:37pm, Dieter wrote:
} > But our power is down every 1~2 week.
} Ouch.  A UPS will help, but even with a UPS you can get a hang/crash
} that corrupts data.  So a UPS is for riding through short outages,
} it is NOT a guarantee that the machine never goes down hard.

     The point of using a UPS is that you also use UPS monitoring
software that properly shuts down your system before it goes down
hard.  The only reason that your system would go down hard is if you
fail to do this or the UPS malfunctions.

} > Once power down occurs, the NetBSD server will check file system
} > at next startup, it will take as long as 10 minutes.
} What you want is:
} 	FFS
} 	soft updates
} 	disk's write cache turned off
} 	background fsck

     What you want is to solve the problem with the power.  Failing that,
you want a journalling filesystem.

} This works great on FreeBSD.  No lost data.  No corrupted data.
} Machine is available immediately after boot.  (Note that the
} background fsck does use up some resources, such as disk i/o.)
} Does NetBSD 4.0 have background fsck?


} > I have done a test on Linux (ext3), it take only 10 seconds to recover.
} But Linux's ext will CORRUPT YOUR DATA!!!  (I'll give you one guess how
} I know this.)  Who cares how fast it boots if your data is corrupted?

     Agreed.  Having a filesystem that is completely async is an
extremely bad design.

}-- End of excerpt from Dieter