Current status of nullfs and/or unionfs?

Emanuel Strobl Emanuel.strobl at
Thu May 5 07:43:41 PDT 2005

Am Donnerstag, 5. Mai 2005 14:06 schrieb Eirik Øverby:
> Hi all,
> I'm struggling with some hosting environments where I am managing a
> large number of jails (>100) spread over about a dozen servers. I am
> starting to see disk space as a real problem, especially given that each
> physical box needs to be autonomous - i.e. I can't rely on any external
> storage, and I am limited to 1U and 2U servers.
> The solution, or at least parts of it, would be to have certain parts of
> the jail filesystems mounted in via nullfs (acceptable solution) or
> unionfs (ideal solution). However, ever since FreeBSD 4.10 this has been
> a major problem, as both filesystems started exhibiting major stability
> and data integrity issues.
> Before I start playing with this again, I'd like to know if any work has
> been done on either of these in 5.x. Specifically, I'm currently running
> 5.3-p6 or newer on all the systems, and as of yesterday I've been using
> 5.4-prerelease (cvsup) on a couple of test systems.
> What can I expect to see when trying nullfs and/or unionfs today? Has
> anything changed? Do I have even a remote chance of making it work - and
> if it doesn't work, what are my chances of anyone having time or energy
> to look into it? I'm an admin only, no coder, otherwise I'd be happy to
> look into it myself.

Nullfs is as far as I can tell stable on 5.4 but the performance problem
together with jails is not solved in 5.4, only in 6. And like Jeff said,
it's not sure that it gets MFCd since lot of VFS changes are requred.


> Thanks,
> /Eirik
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