Hi all,
finally, a comment from someone who has a say in that.
> > this is a diff to faq4.html (the install faq) so that it mentions
> > /altroot for the installing user before he partitions his drive. Now,
> > the altroot feature is described in daily(8), which you only read when
> > you already have a system installed, your disk is already partitioned,
> > and typically you don't have the spare partition (of size at least that
> > of /) to use for /altroot.
>
> what benefit do you see in having /altroot on the same disk as / ?
Silly me, I will use two disks.
OTOH, daily(8) itself gives an example using wd0j.
> > Is using a larger disk in the example a problem? Using a 20G disk makes
> > the point of showing how usable the system is even on a small disk, but
> > 20G disks don't really exist anymore.
>
> Bullshit.
> No functional 10G drive that passes past me hits a trash can.
> No functional 4G narrow SCSI drive that passes me hits a trash can
> either.
> (1G drives are starting to get a bit nervous around here, however)
>
> There are a lot of people who do their first installs (which is what
> the FAQ is pointed at) on very minimal hardware. 20G is actually much
> bigger than many people still use, and loads bigger than many non-i386/
> amd64 systems usually have on them.
>
> So, no, the 80g change is just showing off. No way. At least, not
> until someone floods me with 80G, 120G, 250G and bigger drives enough
> that I think everyone must have big disks. :)
All right. I am well aware that obsd is totaly usable at much smaller
disks; heck, my home router run off 1G for five ears, until it got 2G
this summer; and yes, I know people who run hapilly off a 521M card.
Somehow I got into thinking that these are borderline cases, and the
FAQ example should use something more "typical". Sorry for that
confusion.
> argh. I don't suppose you noticed that OpenBSD developers only use
> diff -u, right? Or actually looked at the output to see why?
OK, lesson learned. Sorry. (First diff I sent.)
> Anyway...
> * your diff makes gratuitous and pointless changes.
> * Those changes will be a pain in the butt for me to maintain, as I
> don't have your machine.
> * It doesn't say a word about the point of the diff (/altroot),
> just silently adds a partition to the install without explanation.
Not true: my single point was that /altroot is at least _mentioned_
in the install FAQ (with a link to daily(8) which explains it), so the
installing user knows that there is such a feature at all - and can
consider that when partitioning.
> * It puts the /altroot partition in a nearly pointless place.
Namely, same disk. Still, your wd0a can die, and you
can boot from wd0j (says daily(8)). But I agree that putting
/altroot an a different disk makes much more sense.
> * 40G home? Only if I had a deliberate plan for why I needed that
> much. Of the dozens of machines I have around here, the only one
> that has a /home that big is my NFS server...
I chalk it up to using the overly big drive in the example.
> An /altroot discussion in the FAQ would be appropriate, but it would
> not be handled anything like this. It wouldn't be a change to the
> install example, it would be in section 4.7, and possibly in a RAID
> discussion somewhere in faq14.html.
>
> /altroot is very cool, but like RAID, it does what it does, not what
> people dream of it doing. I don't think it is in any way an
> "automatic" thing that all users should be doing. I suspect you are
> thinking it will help you if you blow out your 'a' partition.
Yes, I thought this is the whole point of /altroot: a partition
you can boot from, an "alternate root". As in '> boot hd1a:/bsd'.
> About the only thing it can do for you if you have only
> one disk is give you a less-than-a-day-old copy of your config files
> should you do something you regret and catch it soon enough.
> If this is your concern, a better idea would be to tar(1) up your /etc
> and maybe /var files, and stick them in a dated file name, and put them
> in a partition that is only mounted for the backup process. Doing
> this, you can get probably a few MONTHS of past configs for a firewall
> or DNS server in a partition the size you made for /altroot.
Yes, and I of course do that via trivial "tar /etc" script (backups go
over NFS, though). But from these backups you cannot boot, which
I thought /altroot was about.
> Where altroot comes in handy is when you have a pair of disks in an
> already redundant machine (i.e., firewall or DNS server). I did this
> for some systems:
> wd0: 6G
> wd1: 20G or 40G
> wd1 had the same partition layout as wd0, 'cept it also had a big
> partition mounted as /bkup.
> Every night, /etc/daily duped / to /altroot (on wd1), and
> /etc/daily.local made a dated .tgz file of everything in /var and /etc
> and put it in /bkup. /etc/weekly.local used dump or rsync to copy
> the rest of the partitions from wd0 to wd1. If wd1 blows out, there
> is a copy of all the backup files on the other machine in the set
> anyway, no big deal. If wd0 fails, wd1 can take over at pretty much
> any time after a disconnect of the failed drive and a reboot.
> Cheap and easy "mirroring". This system looked like it could hold a
> decade or two of configuration history on those non-existant drives.
I was just about to suggest that I rewrite the diff (-u) using
a combination of two of the 4G, 6G, 10G disks I do have. But you
say mentioning altroot goes into 4.7 anyway ...
> Again, worth repeating, you had an idea, and you followed it through.
> I didn't like the implementation, but the idea (documenting /altroot)
> isn't bad. Feel free to try again (I probably won't have a chance to
> do it for a while myself. Think of section 4.7, under "additional
> thoughts", maybe starting with, "If you have a second disk, you can
> ...")
See at bottom; looks much simpler now, hmm :-)
I leave the RAID analogy to someone else.
Anyway, first diff, screwed up,
thanks for all the comments.
Jan
Index: faq4.html
===================================================================
RCS file: /cvs/www/faq/faq4.html,v
retrieving revision 1.254
diff -u -p -r1.254 faq4.html
--- faq4.html 3 Nov 2007 13:51:09 -0000 1.254
+++ faq4.html 7 Nov 2007 07:31:13 -0000
@@ -1915,6 +1915,13 @@ Some additional thoughts on partitioning
can use <a href="faq10.html#Quotas">quotas</a> to restrict the space
they use, and if they fill the partition, no other parts of your
system will be impacted.
+ <li>If you have a second disk, you might want to create an <tt>/altroot</tt>
+ partition on it, as described in
+ <a
href="http://www.openbsd.org/cgi-bin/man.cgi?query=daily&sektion=8";>daily(8)</a>.
+ This can be used for daily backups of your <tt>/</tt> partition,
+ giving you a possibility to recover should your 'a' partition go away.
+ Obviously, the <tt>/altroot</tt> partition needs to be at least as big
+ as <tt>/</tt>.
</ul>
