Re: what is our answer to ZFS?

From: Bill Davidsen
Date: Mon Nov 21 2005 - 17:39:20 EST

Kasper Sandberg wrote:
On Mon, 2005-11-21 at 14:18 +0100, Matthias Andree wrote:

I don't care what its name is. I am aware it is a rewrite, and that is
reason to be all the more chary about adopting it early. People believed
3.5 to be stable, too, before someone tried NFS...

nfs works fine with reiser4. you are judging reiser4 by the problems
reiserfs had.

reiser4 will have far more problems than 3.5 without a doubt. The NFS problem was because it was a use which had not been properly tested, and that was because it had not been envisioned. You test for the cases you can envision, the "this is how people will use it" cases. He is judging by the problems of any increasingly complex software.

reiser4 has a ton of new features not found in other filesystems, and the developers can't begin to guess how people will use them because people never had these features before. When files were read, write, create, delete, permissions and seek, you could think of the ways people would use them because there were so few things you could do. Then came attrs, ACLs, etc, etc. All of a sudden people were doing things they never did before, and there were unforseen, unintended, unsupported interractions which went off on code paths which reminded people of "the less traveled way" in the poem. Developers looked at bug reports and asked why anyone would ever do THAT? But the bugs got fixed and ext3 became stable.

People are going to do things the reiser4 developers didn't envision, they are going to run it over LVM on top of multilevel RAID using nbd as part of the array, on real-time, preemptable, NUMA-enabled kernels, on hardware platforms at best lightly tested... and reiser4 will regularly lose bladder control because someone has just found another "can't happen" or "no one would do that" path.

This isn't a criticism of reiser4, Matthias and others are just pointing out that once any complex capability is added, people will use it in unexpected ways and it will fail. So don't bother to even think that it matters that it's been stable for you, because you haven't begun to drive the wheels of it, no one person can.

-bill davidsen (davidsen@xxxxxxx)
"The secret to procrastination is to put things off until the
last possible moment - but no longer" -me
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