Messages in this thread | | | Date | Fri, 10 Jun 2011 13:51:27 +0200 | From | Bernd Schubert <> | Subject | Re: [PATCH 0/7] overlay filesystem: request for inclusion |
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On 06/09/2011 09:32 PM, Andrew Morton wrote: > On Thu, 9 Jun 2011 14:49:47 +0100 > Andy Whitcroft<apw@canonical.com> wrote: > >> On Wed, Jun 08, 2011 at 08:52:33PM -0700, Andrew Morton wrote: >> >> The problem with the userspace alternative is that it does not work. I >> tried to run my live CD on top of unionfs-fuse and the filesystem >> would fail intermittently leading to random errors during boot. > > > If the implementation is slow or buggy then the appropriate action is > to speed it up and to fix the bugs, so these are just non-arguments, > IMO.
Exactly. It is rather sad that people never bothered to file bug reports about slow performance issues. I'm one of the upstream authors of unionfs-fuse and also use it on my own for live-USB sticks and NFS-booted systems and do not have such problems.
> > If it is demonstrated that the userspace implementation simply cannot > ever have acceptable performance then OK, we have an argument for a > kernel driver.
Well, I know rather well were most of the performance issues in unionfs-fuse come from (at least the normal issues, not those above where it seems to fail at all). And those issues are mostly unrelated to user-space, but just due to very simple approaches to get a working union implementation at all (neither kernel solution actually does what I need...). The main problem is that I barely find spare time to further improve unionfs-fuse...
Another real difficulty with user-space implementations are init scripts - while it works perfectly with Debian, I always have the feeling that RedHat does everything they to make it impossible to use fuse as root file system (eventually I always get it working, till the next minor release, which breaks all workarounds again).
Anyway, given my lack of time and the resulting slow development of unionfs-fuse, distros probably need another solution for their live CDs.
Cheers, Bernd
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