[PC-BSD Dev] Subject: Re: 9.0 Recommendation: partitioning

QT rdirective at gmail.com
Sun Sep 26 11:52:30 PDT 2010

On Fri, Sep 24, 2010 at 6:27 PM, Roger Marquis <marquis at roble.com> wrote:

>  Suppose you have only a single partition / and want to mount it
>> read-only...how are you going to accommodate this ?  Hm?  I'd imagine you
>> have a terrific time since all inodes reference back to /.  This will
>> include all sub-mount below /...
> Not sure I understand the application but I would guess that less than
> 0.01% of PC-BSD installations would ever want to mount root read-only.
> We should be looking at the other 99.99% for defaults.

The application can be for security, net-boot/headless, testing builds,
quick migration, quick deployment, and others.  Multiple partitions offer
flexibility in multi-user environment that single partition can not.  BSD
was built from the ground up for multi-user environment.  Just because PCBSD
is used primarily by a single user does not mean partition scheme should be
changed to reflect that.  Even in a home environment, one can envision the
PCBSD machine be used by multiple people at once and should
file-system/harddrive error occur, a single partition will cripple everyone
and everything.  In a multiple partition scheme, the affected
filesystem/harddrive can be brought offline for fixing without affecting the
whole system.  This happens all the time and mostly transparent to the users
on clusters and distributed systems.  Case in point, if the Internet was
mounted as single filesystem, we'd be in big trouble.

 The purpose of multiple partition/mount is for flexibility.
> If it is then how do you explain the statistically significant
> correlation between intra-disk partitions and diskfull trouble tickets?
> Partitions may work well for inter-disk partitions (inter != intra) but
> if they made systems administration easier you'd think we would see them
> implemented on raid-based NAS and SAN fileservers.  We don't because they
> aren't.
All NAS and SAN fileservers use partitions.  That is a fact.  In fact, all
distributed filesystems use partitions.  Of course these are usually logical
partitions and not physical partitions...Of course, there is no rule that
said you can't have a single / on NAS, but have fun explaining to your boss
why everything is f*cked when a few disks failed.

As for your "statistically significant correlation between intra-disk
partition and diskfull trouble tickets", that simply said poor planning is
statistically relevant.  Partition accordingly to the requirement of space
usage.  Use appropriate filesystem (PCBSD installs ufs+journal by default).
If you know your application is space hungry, then use logical partition on
a volume manager so you can grow on the fly.  Use the right tool for the
right job.  Partitioning is only a tool.  Apply it stupidly and you will get
stupid results.

> Roger
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