At least on the x86 architecture, shared libraries are not entirely madeup of position independent code. This means that there is a certainamount of relocation that you have to do when you load a shared libraryinto memory at run time. The basic idea behind prelinking is to try todo this relocation ahead of time; for each shared library, you pick adefault location in memory and 'prelink' it so that if it is loaded atthat location it doesn't need any run-time relocation

The other problem with certified email asa way to solve the spam problem is a basic idea:

People don't pay for what they don't need.

So ask yourself: who actually needs to pay for a certification that theiremail isn't spam?

Significant sources of good email certainly don't need to pay; peoplealready want email from them and will raise heck if stuff startsgetting blocked. No one can afford to block GMail, for example.

There's some motivation for smaller sources

Consider a fileserver and SAN environment where you have a number offrontend NFS fileservers and a number of backend SAN disk units, with atleast as many backend disk units as fileservers. The obvious sensibleway to split the disk units among the fileservers is to have each SANunit used by only one fileserver, because that makes various things mucheasier to manage.

(You might even be tempted to design an infrastructure around theassumption that disk units won't be shared.)

The problem with staying this way is that

Right from the early days of vendor provided Unix, two things wererelatively obvious to people: first, you were going to need to adda bunch of local programs to make the system really useful to yourusers, and second, adding local programs to vendor areas like /bin or /usr/bin was a pretty sure road to doom and disaster. So peoplestarted putting them somewhere else.

(The most famous example is that BSD Unix put a bunch of their additionsin /usr/ucb , which then

ZFS needs a zfsdump program for the same reasons that every filesystemneeds a *dump program: you need something that can fully and completelyreproduce the state of the on-disk data, complete with sparse files andweird permissions and so on, and can restore small portions of thebackup not just the whole thing.

(In this day of more and more people turning off atime , it's probably no longer so important tohave a backup tool that is guaranteed not to change the state of files.)

Generalized

I think that you should prewire experimental racks for power. By thisI don't mean just making sure that they have some PDUs in them; I meanrunning actual power cords up the sides, with unconnected ends tiedoff every so often ready to be plugged into machines. If you turn outto need more power cords for a machine, don't try to run more powercables along the side unless they too are going to be permanent; justdangle them down the back, where they are easy to

A modern Unix system carries around with it all sorts of historicalrelics . One of them is /usr/share , whichwas a relic of another era until recently (when multi-architecturemachines started appearing).

Once, by now long ago, disk space was a lot more limitedand heavily NFS dependent networks were much more common . Because disk space was so scarce, youdidn't put big locally-built programs like TeX or Emacs or the latestX Windows on every machine's disk; generally

Dear F-Spot and similar applications: please understand that I alreadyhave a digital photo 'workflow'. However peculiar it is, it works finefor me and I have no interest in having you replace it; all I want todo is edit a photo every now and then. Can't you just let me do that,without making me import all of my photos into your world or otherwisegoing through all sorts of contortions?

Or in short: if you make me choose all or nothing, I

There are a number of schemes for dealing with spam that boil down to'people will get SSL certificates, you only accept email with a validcertificate, and if people still spam the certificate authority willrevoke their certificate'. There is a simple, core problem with theseschemes:

Certificate revocation never works.

Certificate authorities are paid by the people who they issuecertificates to, not by the people accepting those certificates. Thepeople who provide the money do not want their certificates revoked, andso it is not in