On Sat, 15 Dec 2012 10:16:05 +0200 nunojsi...@ist.utl.pt (Nuno J. Silva) wrote:
> On 2012-12-14, Mark Knecht wrote: > > > I guess the other question that's lurking here for me is why do you > > have /usr on a separate partition? What's the usage model that > > drives a person to do that? The most I've ever done is > > move /usr/portage and /usr/src to other places. My /usr never has > > all that much in it beyond those two directories, along with > > maybe /usr/share. Would it not be easier for you in the long run to > > move /usr back to / and not have to deal with this question at all? > > I may be wrong in this one, but the idea I have is that your regular > applications (so, most of them) all lie under /usr/ -- /lib /bin and > others are for essential system tools. > That was the original reason for having / and /usr separate, and it dates back to the early 70s. The other reason that stems from that time period is the size of disks we had back then - they were tiny and often a minimal / was all that could really fit on the primary system drive. Gradually over time this setup became the norm and people started to depend on it, and more importantly, started to believe it was important to retain it. It's their right to believe that. Recently I decided to measure if I still needed a separate /usr (I was a long time advocate of retaining it). I'm in the lucky position of having ~200 Linux machines, all distinctly different, at my disposal, so I trawled through memory and incident logs looking for cases where a separate /usr was crucial to recovery after any form of error. To my surprise, I found none at all and those logs go back 5 years. So I got to change my mind (not something I do very often I admit) and concluded that separate base and user systems (/ and /usr) was no longer something I needed to do - the "system" - disks, hardware and the software on the disks - was very reliable, and what I really needed was ability to boot from USB rescue disks. I did find, not unsurprisingly, that I also really needed /usr/local on a separate partition but that's because of how we install our in-house software here, plus our backup policies. It also goes without saying that these days we need /home, /var, /var/log and /tmp to all be on their own filesystem, and we need that more than ever. I thought I should just toss that in the ring for people who are undecided where they stand on the debate of separate / vs /usr. It's what I found on our production, dev and staging servers, plus a whole lot of people's personal workstations (sysadmins and devs). The environment is a large corporate ISP that defies categorization, we almost have at least one of every imaginable use-case for running on Linux except something in the Top 100 SuperComputer list. I reckon it's about as representative as I'm ever gonna see. People are free to draw their own conclusions as always, and real data is valuable in arriving at those conclusions. YMMV. -- Alan McKinnon alan.mckin...@gmail.com
