Re: [9fans] kfs and cwfs comparison

[errno <errno@cox.net>]

On Sunday, April 24, 2011 09:10:22 AM erik quanstrom wrote:
> <snipped>

Thanks for satisfying those questions, much appreciated!

On Sunday, April 24, 2011 08:01:01 AM Steve Simon wrote:
> Ideally there would be a wiki page on this - I will have a go shortly...
>

That would be helpful; looking through the archives, I can see
that similar questions - regarding the effective differences between
the various plan 9 disk fs's - have been brought up on the list before.



On Sunday, April 24, 2011 09:10:22 AM erik quanstrom wrote:
> > How about in terms of resources/overhead - is kfs more appropriate in
> > constrained/embedded devices than cwfs?
>
> by default, kfs just uses 10mb of memory.  i haven't run cwfs enough to
> say with any confidence how well cwfs does.  but kfs will use less disk
> space (and if no changes, constant space) since old copies are not kept.
>
> > Or maintainability? Are kfs and cwfs both relatively equal in terms of
> > maintenance and/or disaster recovery?
>
> both have a weak spot.
> kfs.  there's one copy of the file system.  if you corrupt it, you're out
> of luck.  i've never seen this happen.
>
> cwfs.  if the fs is halted during the dump, there is a non-zero chance
> of corruption.  i have seen this, but "recover main" can usually roll the
> fs back to the last good dump.  the same mechanism can recover a fs
> if an untimely shutdown has corrupted the cache.
>
> > Are kfs and cwfs equally dependable/stable?
>
> i would say so.
>
> > Finally, what about the difference between a terminal and
> > auth/cpu/fileserver - would kfs/cwfs be more or less appropriate for a
> > terminal vs. a server?
>
> it depends.  i would tend to use kfs only if i were storing my real data
> someplace else.  i find the lack of history to be a big problem.  but then
> again, i tend not to run fses on terminals.  i just run ken's fs and am
> done with it.  :-)
>
> - erik