[ale] Separate /opt partition

[Jeff Lightner]

The downside to /tmp being in memory is that it decreases memory for
other processes.   Also as we've recently discovered at my job Oracle
R12 has an issue with directing temporary files to separate areas
designed for job like 11.5.9 did which meant we had to increase /tmp to
an ungodly size as a work around.  Back when I worked on Solaris by
default it use /tmp in RAM but we manually moved it off to a disk
filesystem as we found the reduction in memory to processes outweighed
the benefit of having fast /tmp.

I don't get the thing about swap if you're using external RAID.  We use
swap on LVM on the same RAID device we have the rest of the OS
filesystem LVMs and haven't seen any issues doing that.  If it is
external RAID the work is all being done by RAID controller or the array
itself so other than basic LVM overhead which is negligible I can't see
the benefit of what you suggested.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
Daniel Kahn Gillmor
Sent: Tuesday, November 18, 2008 8:07 PM
To: ale at ale.org
Subject: Re: [ale] Separate /opt partition

On Tue 2008-11-18 15:39:24 -0500, Scott Denlinger wrote:

> Since you're using Ubuntu, which is based on Debian, you might want
> to consider putting software not managed by Ubuntu into
> /usr/local. This is Debian's "official" suggestion for packages not
> managed by the packaging system. But the choice of /opt versus
> /usr/local is likely six of one and half dozen of another.

Debian actually defers in this context to the filesystem hierarchy
standard (FHS):

  http://www.pathname.com/fhs/

The FHS is not debian-specific.  It's worth reading if you're learning
your way around a modern UNIX filesystem, though not every UNIX system
is as rigorous about adhering to it as debian is.

Re: tmp as a separate partition: it's also worth considering using a
tmpfs for /tmp if you're using a modern linux kernel.  The /etc/fstab
would look like this:

 tmp /tmp tmpfs defaults,nodev,nosuid,mode=1777 0 0

this keeps the filesystem in RAM and guarantees that it will be
ephemeral.

Also, for folks considering LVM-on-RAID (with /boot as a separate
physical RAID1), you probably also want to consider separate physical
partitions for swap.  Otherwise, your swapouts will have the cost of
writing to a RAID, which can disastrously compound situations when
you run out of RAM.

  --dkg
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