Amateur grounding is probably the easiest, most effective, and least-understood method of messing up your equipment, your home, and probably yourself.
If you need better grounding, or think you do, and don't understand it well, then get a good electrician.
With that said:
You can get a 3-4 foot copper clad steel rod
You would want a steel-clad copper rod, not the other way 'round. Exposed copper will quickly oxidize into an amorphous, non-conducting blob. The steel should be galvanized, of course. Aluminum or a similar "rustless" covering is good, too.
If you need to add a better ground to your house...
Then you need to remove the inferior ground from your house first. This is a must-do. If you have >1 ground point, imagine what happens when lightning hits that shiny new ground rod you installed...
There's suddenly a huge positive potential at the rod, which will dissipate as quickly as possible wherever it can. It takes a while to do that, though, because the earth doesn't have a high density of delocalized electrons. It takes lots of earth, and some time, to sort out the potential difference introduced by a strike.
With just one ground point, you're pretty much OK -- there aren't enough idle electrons in your equipment (compared with how many there are in the earth surrounding the rod) to do much damage.
With a second ground point, though, there are *zillions* of handy electrons near the earth around the other ground rod.
They will flow from the old ground, up to your house, through your equipment (depending on exactly how things are wired), and out to the new ground. Before it burns out your wiring and sets your home on fire, this current will be very large.
Incidentally, this is also why it's not good to be near a lightning strike and standing on open ground. If your feet are planted, you have two ground points. There can be ~1e5V potential difference between one foot and the other as the charge dissipates. Without heavy rubber soles, that difference will resolve itself by sending current through your low-resistance legs and crotch. If you're holding a tree or metal rail or other somewhat-grounded thing, then add "heart, lungs, and spine" to "legs and crotch" above. Not fun.
We use Networker to back up ~500 GB, spread across 30 clients (NT, Digital Unix/Tru64, and Linux). Backup performance is excellent (by interleaving sessions over two network cards and the local disks, it can keep two loaders running at ~5MB/sec each).
I don't know what the maximum "partition" size is, but we've backed up 150GB file domains with no problems.
Restore performance is slower, of course, but emphatically not an "all day event"; it takes a few seconds to find what you need in the database, and a couple minutes to load the tape (we're using twin 280GB DLT loaders). After that, the speed is the same as it would be for tar/dump/whatever; the tape drive must seek to your files and read, and that can take up to an hour.
If your files are spread across mutiple tapes (either because you're using incremental or differential backups, or because a single saveset spans multiple tapes), then it can be as long as two hours. If you have only a few clients, these times are reduced somewhat.
The only time I've spent an entire day doing restores is when we lost the Networker server (and its media indices), and had to use Networker's bootstrap procedure to bring back the index, followed by regular restores to bring back everything else. Because I hadn't bothered to keep hardcopies of the logs, Networker had to scan the tapes for a suitable bootstrap. The searching alone took a few hours.
A couple caveats, though: it's not cheap, and it's not easy.
Networker was designed for the kind of environment we've set up, and you may find it overkill for one or two clients. The GUI is marginal, but the command-line tools can completely eliminate it, and do more besides.
Expect to spend a couple of weeks configuring it, and a couple more getting comfortable with the (extremely powerful, IMHO) command-line tools.
You'll need a cabable server to hold the media indices -- we keep data in the index for a Quarter, and the database is over 2GB. We're using a dual-CPU Alpha 4100 @600MHz w/2GB memory, running Tru64 Unix (it's used for a number of other things, of course).
NB: starting with Networker 5, you can have the tape devices and databases on separate machines, which reduces the need for one mammoth server to do backups and media management. It's also good if you have mutiple sites separated by sub-LAN-speed links; you can put a tape device on each LAN.
It's a piece of cake to wire a relay to a parallel port...
Just a couple comments:
This is a pretty neat idea. You could use a transistor (2N2222 or equivalent) and avoid relays and all their clunkiness (mainly, the need for Vcc, which is tricky to get from a parallel port). The PS recommendations at the ATX site (see link in some other comment) say =1.6mA through the PS_ON line, which is no problem for even a tiny component.
If you're really lazy, you could probably get away with driving the lines directly from the parallel port (eek)... use a separate card (not an onboard port) for this.
Also, you could hijack the status lines on the parallel port, in addition to the data lines, and control a couple extra machines with those pins.
And, if you're interested in doing something like this but don't know what a transistor is, see a dirt-simple description I wrote of a device that does almost this exact function (grounds a line under program control). There's a nifty schematic and some source there, too.
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If you need better grounding, or think you do, and don't understand it well, then get a good electrician.
With that said:
You would want a steel-clad copper rod, not the other way 'round. Exposed copper will quickly oxidize into an amorphous, non-conducting blob. The steel should be galvanized, of course. Aluminum or a similar "rustless" covering is good, too.
Then you need to remove the inferior ground from your house first. This is a must-do. If you have >1 ground point, imagine what happens when lightning hits that shiny new ground rod you installed...
There's suddenly a huge positive potential at the rod, which will dissipate as quickly as possible wherever it can. It takes a while to do that, though, because the earth doesn't have a high density of delocalized electrons. It takes lots of earth, and some time, to sort out the potential difference introduced by a strike.
With just one ground point, you're pretty much OK -- there aren't enough idle electrons in your equipment (compared with how many there are in the earth surrounding the rod) to do much damage.
With a second ground point, though, there are *zillions* of handy electrons near the earth around the other ground rod.
They will flow from the old ground, up to your house, through your equipment (depending on exactly how things are wired), and out to the new ground. Before it burns out your wiring and sets your home on fire, this current will be very large.
Incidentally, this is also why it's not good to be near a lightning strike and standing on open ground. If your feet are planted, you have two ground points. There can be ~1e5V potential difference between one foot and the other as the charge dissipates. Without heavy rubber soles, that difference will resolve itself by sending current through your low-resistance legs and crotch. If you're holding a tree or metal rail or other somewhat-grounded thing, then add "heart, lungs, and spine" to "legs and crotch" above. Not fun.
cheers,
mike
ftp://ftp.legato.com/pub/Unsuppor ted/Linux_Client/ has both 4.2 and 5.1 client kits, in .gz and .rpm formats. The clients are unsupported, but they work well for us.
We use Networker to back up ~500 GB, spread across 30 clients (NT, Digital Unix/Tru64, and Linux). Backup performance is excellent (by interleaving sessions over two network cards and the local disks, it can keep two loaders running at ~5MB/sec each).
I don't know what the maximum "partition" size is, but we've backed up 150GB file domains with no problems.
Restore performance is slower, of course, but emphatically not an "all day event"; it takes a few seconds to find what you need in the database, and a couple minutes to load the tape (we're using twin 280GB DLT loaders). After that, the speed is the same as it would be for tar/dump/whatever; the tape drive must seek to your files and read, and that can take up to an hour.
If your files are spread across mutiple tapes (either because you're using incremental or differential backups, or because a single saveset spans multiple tapes), then it can be as long as two hours. If you have only a few clients, these times are reduced somewhat.
The only time I've spent an entire day doing restores is when we lost the Networker server (and its media indices), and had to use Networker's bootstrap procedure to bring back the index, followed by regular restores to bring back everything else. Because I hadn't bothered to keep hardcopies of the logs, Networker had to scan the tapes for a suitable bootstrap. The searching alone took a few hours.
A couple caveats, though: it's not cheap, and it's not easy.
Networker was designed for the kind of environment we've set up, and you may find it overkill for one or two clients. The GUI is marginal, but the command-line tools can completely eliminate it, and do more besides.
Expect to spend a couple of weeks configuring it, and a couple more getting comfortable with the (extremely powerful, IMHO) command-line tools.
You'll need a cabable server to hold the media indices -- we keep data in the index for a Quarter, and the database is over 2GB. We're using a dual-CPU Alpha 4100 @600MHz w/2GB memory, running Tru64 Unix (it's used for a number of other things, of course).
NB: starting with Networker 5, you can have the tape devices and databases on separate machines, which reduces the need for one mammoth server to do backups and media management. It's also good if you have mutiple sites separated by sub-LAN-speed links; you can put a tape device on each LAN.
cheers,
mike
This is a pretty neat idea. You could use a transistor (2N2222 or equivalent) and avoid relays and all their clunkiness (mainly, the need for Vcc, which is tricky to get from a parallel port). The PS recommendations at the ATX site (see link in some other comment) say =1.6mA through the PS_ON line, which is no problem for even a tiny component.
If you're really lazy, you could probably get away with driving the lines directly from the parallel port (eek) ... use a separate card (not an onboard port) for this.
Also, you could hijack the status lines on the parallel port, in addition to the data lines, and control a couple extra machines with those pins.
And, if you're interested in doing something like this but don't know what a transistor is, see a dirt-simple description I wrote of a device that does almost this exact function (grounds a line under program control). There's a nifty schematic and some source there, too.
cheers,
mike