Partition naming, fstab, and geli
freebsd at edvax.de
Mon Nov 16 03:21:35 UTC 2009
On Sun, 15 Nov 2009 19:23:15 -0700, David Allen <the.real.david.allen at gmail.com> wrote:
> 1. The Handbook suggests there is a convention that when partitioning a a
> drive that's been added, to label the first new partition on that drive as
> 'e' as opposed to 'a' (which is reserved for the /root partition). Does
> the following satisfy that convention, or would starting with 'a' in each
> case make more sense?
> /dev/ad1e /foo1 ufs rw 2 2
> /dev/ad1f /bar1 ufs rw 2 2
> /dev/ad1g /baz1 ufs rw 2 2
> /dev/ad2e /foo2 ufs rw 2 2
> /dev/ad2f /bar2 ufs rw 2 2
> /dev/ad3e /foo3 ufs rw 2 2
> /dev/ad3f /bar3 ufs rw 2 2
The Handbook says in 18.3.1 sub 3:
A disk can have up to eight partitions, labeled a-h.
A few of the partition labels have special uses.
The a partition is used for the root partition (/).
Thus only your system disk (e.g, the disk you boot
from) should have an a partition. The b partition
is used for swap partitions, and you may have many
disks with swap partitions. The c partition addresses
the entire disk in dedicated mode, or the entire
FreeBSD slice in slice mode. The other partitions
are for general use.
Note the last sentence. Due to this statement, I think the
usage of 'e' is arbitrary, 'd' could be okay, too, but when
the Handbook says 'e' in the example (maybe with the intention
of 'e' like in 'example'?), you can use 'e', too, especially
when you want to use more than one partition.
I have to admit that I never put slices on extra hard disks,
I'm always using the whole disk, so
# newfs /dev/ad3
would give me /dev/ad3 (which is the same as /dev/ad3c), and
/dev/ad3 /foo ufs rw 2 2
would go into fstab.
I'm sure you already know this because it seems that you read
up until 188.8.131.52 - you're omitting slices, "dedicated" mode. :-)
Bottom line: The naming convention mentioned in the Handbook
and your examples are completely okay.
> 2. My second question is in regards to using the 'xx' fstype to have the
> system ignore that device.
> Consider, for example, a geli encrypted partition. The .eli device
> doesn't exist at boot time. I discovered by accident that the system
> won't boot with an fstab entry for a device that doesn't exist.
That's completely intended. :-)
> So if I
> was to record an entry in fstab, I couldn't use
> /dev/ad1e.eli /home/david/private ufs rw 0 0
> Does that mean that the following is what's typically to record fstab
> entries for ignored devices?
> /dev/ad1e.eli /home/david/private xx rw 0 0
> /dev/ad3e /fake xx rw 0 0
> /dev/ad3f /reserved xx rw 0 0
I would say: No. The entry for those partitions should rather be:
/dev/ad1e.eli /home/david/private ufs rw,noauto 0 0
/dev/ad3e /fake ufs rw,noauto 0 0
/dev/ad3f /reserved ufs rw,noauto 0 0
The "ufs" in the FS field tells the system which FS to use when
later mounting (e. g. with requiring a pass phrase from the
operator), and "noauto" in the options field that prohibits
mounting the file system at startup.
If you used "xx" in the FS field, you could not easily
# mount /reserved
because the mount command wouldn't know which FS to use (allthough
I think UFS might be a default here).
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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