Once upon a time, Unix was very small and fit entirely in what is nowthe root filesystem, / ; hence, among other things, /bin , whichwas where commands went. This didn't last very long, and by the timeof at least the Third Edition in 1973, there was an additional /usr filesystem with a /usr/bin for 'overflow' programs that didn't fit onthe root filesystem any more.

(As I heard the story, the root

There's recently been a little bit of fuss in the news about the NewYork Attorney General getting various ISPs to turn off the alt.*hierarchy on their Usenet servers, with a number of people are wonderinghow the ISPs were willing to cave in to this sort of pressure. My guess,based on what I remember from being fairly involved with a Usenet serverup until a couple of years ago, is that ISPs were probably just as happyto have a good excuse to cut back on their news servers

Since I was just looking into this recently, I will write down what I'velearned about the less obvious effects of some of the fdisk commands.

The u command

As a side effect of switching to using sectors asthe size unit, fdisk stops rounding up the end of your partitionsto the nearest track or cylinder boundary.

The c command

This stops fdisk from rounding up the start ofpartitions to the nearest track or cylinder boundary. (Fdisk givesthis the cryptic description of turning off "dos compatibility".

It's time for me to say something nice about ZFS for a change, becauseZFS can make the big RAID-5 problem significantly less of a problem for many people. ZFS offers twosignificant advantages:

• because it knows what parts of the array actually contain live data,it doesn't need to read all of the disks. Less data read means lesschance of an unrecoverable read error.

  (How much of an improvement this is depends on how full your poolsare; if you routinely run with very

Let's start by talking about drive failure modes andhow they're measured. Hard drives have both MTTF , the rateat which they fail completely, and UER , the rate at which they report an unreadable sector. Drive MTTFis expressed in hours, but drive UER is expressed as a function of howmuch data is read (technically as 'errors/bits read').

(Typical consumer drive drive UER is apparently 1 per 10 ¹⁴ bits read; 'enterprise' disks improve this to

The more I think about it, the more I think that there are a numberof conditions that need to hold in order for overlapping windowsto make sense (or at least to be attractive). I also think thatthese conditions are not necessarily all that prevalent, which maygo a long way towards explaining why tabs and maximized windows are so popular.

First, small displays lead to maximized windows (and thus tabs) becausethere isn't enough space to go around. This isn't just resolution,

One of the strange networking mysteries around here is that every sooften, one of our login servers will report that outgoing mail wasdelayed because it could not connect to the mail server's SMTP port.There's several things that make this puzzling:

• the connection is failing with 'host not reachable' errors, not'connection refused' or the like
• the mail server is up, running fine, and not loaded at all
• the login servers and the mail server are on the same subnet,although they are

While it is true that in general software doesn't wear out , this is not true for software thatinteracts with the Internet. Internet software definitely breaks downover time, not because of any analog to mechanical wear but because theInternet environment it operates in keeps changing.

There are three sorts of changes in the Internet environment thatmatter. First, protocols and other programs that interact with youevolve over time. Second, user expectations also evolve. Third and mostimportantly, the Internet threat environment itself keeps changing,

If you are going to charge for things , one ofthe eternal questions is whether you should use detailed usage chargesor simpler, 'flatter' ones. My personal thoughts run something likethis:

If you have a fixed service that you're expanding slowly (if atall), detailed charges theoretically extract the maximum value forit. However, they do so at the cost of driving away users who don't likethe unpredictability of their bills, and every so often you will havesomething go horribly wrong