On Tue, Mar 29, 2005 at 05:36:57PM -0800, Greywolf wrote:
> [Thus spake Sean Davis ("SD: ") 8:30pm...]
> 
> SD: I've got three out of four (everything but my root / main stuff disk) disks
> SD: running with softdeps, and while they DO perform better with softdeps, I've
> SD: noticed some drawbacks, such as when (for example) untarring pkgsrc. If I'm
> SD: doing it on a softdep'd partition on a nice fast disk (this box is an
> SD: XP2700+ with 1GB ram) it'll complete in about 19 seconds - then lag the HELL
> SD: out of the machine as it actually goes about doing the real writes. To the
> SD: point where it almost feels like it's hardlocked the system. I've had this
> SD: happen several times, only on softdep'd filesystems.
> SD:
> SD: - Sean
> 
> My problem with softdeps is untarring into an already populated filesystem
> which is near capacity.  Because the files don't get recorded as truncated
> or overwritten, it overflows the filesystem.  I have to remount with
> "nosoftdep,noasync,sync" in order to avoid it.

Yuck, I'd never seen that happen, or even thought about it. But it just adds
to my bucket of reasons why I refuse to trust softdep with /, /var, anything
the system can't live well without. Basically I look it thinking about the
old "There Is No Such Thing As A Free Lunch" axiom: if I'm gaining such
drastic speedups in untarring, I must be losing something else somewhere else.
For me, that tends to manifest itself in a LOT of system lag during/after
the untar, and that lag never happens on non-softdep'd filesystems.

- Sean

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