UFS2 filesystem and filesize limits

[Bruce Evans]

On Sat, 3 Jul 2004, Bruce Evans wrote:

> On Fri, 2 Jul 2004, Kenneth D. Merry wrote:
>
> > On Fri, Jul 02, 2004 at 10:37:59 -0600, Kenneth D. Merry wrote:
> > >
> > > I've searched a bit on the list archives, but didn't find an obvious answer
> > > so I thought I'd ask:
> > >
> > > What is the maximum possible size of a UFS2 filesystem?  Are there any
> > > gotchas associated with going that large?
> > >
> > > What is the maximum possible file size on a UFS2 filesystem?
>
> It is given by the same formula as for any ffs file system.  The main limit
> ...

Forgot to answer the first question.  I think the maximum possible size for
an ffs file system is supposed to limited only by block addressibility.  So
for ffs1 the limit is 2**31 * <logical block size> and for ffs2 it is
2**63 * <logical block size>.  The latter is much larger than other
implementation-specific limits, so it is no limit at all.  FreeBSD has
OFF_MAX = 2**63 - 1.  FreeBSD-[2-4] has a device access limit of 2**31
DEV_BSIZE blocks = 1TB.  FreeBSD-5 has a device access limit of 2**63
DEV_BSIZE blocks = larger than OFF_MAX, so not the limit (but since
DEV_BSIZE is usually smaller than <logical block size>, this limit would
be the effective one in other implementations).

Bruce