A how-to guide which you might wish to use for freebsd advocacy

[Warner Losh]

On Thu, Aug 18, 2016 at 4:57 PM, Julian H. Stacey <jhs at berklix.com> wrote:
> "Jukka A. Ukkonen" wrote freebsd-advocacy at freebsd.org:
>>
>> https://www.facebook.com/notes/jukka-ukkonen/upgrading-the-storage-disk-to-finnsat-fh05-hdr-digital-tv-receiver-while-retaini/10208639116987804
>>
>> Feel free to publish the link on the freebsd web site or otherwise
>> distribute it further.
>
> I added cc: freebsd-fs at freebsd.org as it's about file systems & Ext2 & offsets.
>
> (BTW I have no facebook login, so can assure readers Jukka's
> page is public, no fbook login needed to access URL)
>
> An extract re FS.
>
> ] FreeBSD will by default not accept the Finnsat generated partition
> ] for mounting. The trick is that Finnsat creates partitions with
> ] slack alignment. FreeBSD knows that a live ext2fs has to be a
> ] multiple of 4kB, 4096 bytes in size, i.e. 8 disk blocks, 8*512
> ] bytes. If the partition size is not perfectly aligned, FreeBSD does
> ] not allow read-write mount to an ext2fs instance. With all likelihood
> ] it might be a broken file system. Why should FreeBSD help making
> ] things worse?
> ]
> ] So, you will have to adjust the partition size such that its length
> ] will be a multiple of 8 disk blocks. The tool for this is gpart
> ] (geom partition) which both modifies the partition tables and shows
> ] their contents. First use the command
>
> Thanks Jukka,
>
> I've bcc'd a friend who I discussed Humax TV recorders with a while
> back, on similar issues, some time when I'm visiting the town where
> my 3 Humax owner friends are, I hope to find time to experiment
> with my USB to SATA converter.
>
> This thread is archived here:
> http://lists.freebsd.org/pipermail/freebsd-advocacy/2016-August/004619.html
> & under here:
> http://lists.freebsd.org/pipermail/freebsd-fs/2016-August/date.html

This has been a problem for a while. gpart is too smart. It won't allow one
to create unaligned partitions, even when you know they will work.

Warner