Partitioned loopbackdevices

Posted Nov 13, 2004 13:18 UTC (Sat) by Duncan (guest, #6647) [Link]

Well, you asked...

hda1 boot, 2,3 root and root-mirror (root copied to root-mirror
periodically, when I know stuff is working, so I can just switch roots at
the boot prompt if an update screwed things up and I can't boot my working
root), 4 is of course the extended partition, mapping the additional
logical partitions. That takes care of the four primary partitions.

5 and 19 are /usr and usr-mirror, giving me a backup /usr in the event an
update screws my working copy up.

6-8 are my Gentoo portage partitions (which would normally be
under /usr/portage, thus their location after /usr), 6 being the
equivalent of /usr/portage, getting it off of /usr as it's rsynced as part
of my daily update, 7 being the package sources (as opposed to the Gentoo
portage ebuild install scripts on 6), and 8 being binary packages created
at source merge time, so I don't have to go recompiling if I have to
backup a version or two. The partitions serve to size discipline each of
these, of course.

9 and 10 are /usr/src and /usr/local, thus getting them AND
the /usr/portage dirs off of the /usr partition making mirroring it much
simpler. src doesn't need mirrored as the stuff there is easily replaced
from the net, and local is mirrored to another disk.

11-13 are /var, a separate /var/log for size control reasons, and a
separate ccache partition (which by default would be a subdir of /var).

14 is an empty /opt partition. 15 is a 10 gig /home (again, the backup is
on another disk). 16-18 are my dedicated mail, news, and media
partitions, also relatively large (20 gig mail archive, 8 gig news cache
only, 40+ gig media archive, respectively). Thus, the 10 gig home is
PLENTY big, even for duplicated backup user dirs.

After 18, my media partition, is the 100 gig of blank space, allowing for
expansion of the media partition or other flexibility as desired. 19 as I
mentioned is the usr-mirror. 20 is a quite large 15 gig /tmp. I could
easily do with just a gig, but I have the room, and I decided to
appropriate enough space for it so I could stick a couple DVD images there
if necessary, when I was partitioning. Also, emerge can take up to 5 gigs
or so of tmpspace for packages such as OOo, according to reports, and
while that's normally in /var/tmp for security in multi-user situations,
that's not an issue here, so I have portages tmpspace mapped to /tmp,
allowing me to avoid yet ANOTHER partition for /var/tmp.

Note that I don't mention swap partitions. I have a gig of memory, and
decided to disable swap in my kernel config, as I didn't need it and it
only added needless complication and code complexity to the kernel. (On
AMD64's flat memory architecture, the memory zone issues that cause
problems with swap disabled on ia32 don't apply, and the first one that
might hits at 4G, so with only a gig, I'm safe with it too.) I had done
that while running Mandrake, so eliminated the swap partitions when I
wiped Mandrake and reorganized Gentoo on the remaining space.

I mentioned a second disk. It's far smaller, only 36G, but I still keep
two additional copies (backup-working and backup-backup) of / and /usr on
it, meaning I have four copies of those critical partitions, a working and
a backup copy on each of a working and backup disk. It has additional
(single) partitions for /var, /usr/local, and /tmp, and a copy of the
critical personal data from /home as well.

With all that, I keep two copies of both disk's partition tables in /root,
root's home, on the / partition, meaning a total of EIGHT copies of the
partition tables, two each in four different /root homedirs. Likewise
with fstab in /etc, eight copies of that as well (plus automated edit
backups in fstab~).

I could have accomplished the same goal using mount --bind and fewer
partitions, putting all the /usr subdir partitions on one partition in
different subdirs mount-bound as appropriate, for example. That would
have kept me under the 16-partition barrier, and is actually what I may
end up doing when I upgrade to SATA. However, the 20-partition thing has
worked out quite well on PATA. I actually had a few more partitions (24,
I think) when I was dual booting Mandrake and Gentoo, as I learned about
Gentoo and made the switch. However, I reorganized things when I killed
my Mandrake install, just as I had for it when I killed my MSWormOS
install.

As for LVM, I've not learned it yet, and besides, it'd only be something
else that could go wrong. I do fine without it, tho I'll probably take
the trouble to learn it at some point.

Duncan