fdisk maximum partition size

dpk dpk at dpk.net
Wed Aug 10 14:28:24 GMT 2005

On Wed, 10 Aug 2005, Valerio daelli wrote:

> Hi all
> does anyone know any maximum limit to the slice size in freebsd?
> We would like to create a filesystem of 2.2T.
> Is there any limit in fdisk and bsdlabel?
> Thanks a lot

fdisk does not support >2TB partitions -- at least, I've been unable to
get it to work, just gives me zeros. From the advice I've read, what you'd
be best off doing is skipping fdisk and labeling and just run newfs
against the drive itself. IE:

newfs /dev/da0

Of course, this means you will not be able to boot off of the large
device. That's the price we pay for being "on the cutting edge".

There are still several utilities that do not yet handle large partitions
-- the project page is available here:


Another option for you is available if you're using the 3Ware cards: you
can enable "auto-carving" in its BIOS, to split the device into 2TB
chunks. FreeBSD 5.4-RELEASE can only read the first of these chunks, but
if you update to 5.4-STABLE, with its new twa driver, you can access the
other chunks. (* There may be a better term than "chunks", but "slices"
and "partitions" are already used interchangably (and non-interchangably),
so I'm going with chunks.) This works out pretty well in practice except
for having to divide files between mount points by hand.

If you run into any panics or bugs about this please open PRs. There only
seems to be a few of us FreeBSD users with multi-terabyte partitions and
there are still some bugs to be worked out. You may not be able to get a
kernel dump (I wasn't, even with 5.4-R and <1TB partitions (had to put the
server into production before I could report this bug unfortunately))
but you could still get a backtrace for the developers to use.

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