Kindly ask for advice: How can two Macs share one external HD?

[ozymandius]

We have two Mac Minis. I have just added a Western Digital 500GB external drive that connects to both computers via Firewire. We use two Firewire 400-800 cables from each computer, connecting to the two Firewire 800 inputs on the HD. The primary reason for the external drive is to share files from Mini to Mini and backup for each.

Do I need a Firewire router? Is there a networking issue between the two computers, bypassing either a drive or router, that needs to be resolved?

Any assistance you can provide on this subject would be wholeheartedly appreciated.

:hi:

[struggle4progress]

1. Not sure, but I think you need a network drive to do what you want to do: connect the macs and the

network drive to a router

But there may be a cheap substitute that might work almost as well for you, depending on what you want to do: connect the two minis via ethernet

Connecting two computers using Ethernet
http://docs.info.apple.com/article.html?path=Mac/10.4/en/mh914.html

You may have to tinker with sharing and permissions to get this to work

[ozymandius]

4. Thank you.

You answer the router question. Currently, I only have one router as traffic cop between the two Macs. An additional router and server looks to be necessary for sharing permissions.

[struggle4progress]

7. I think you missed the point of the link I supplied: Apple claims that if only two machines

are involved, you can simply connect them by ethernet cable between the ports. You then need to explore how to set appropriate System Preferences. A convenient first step is to try to enable screen sharing, so that one can view the screen of one (or each) computer in a window on the screen of the second. Screen sharing alone won't get you everything you want, but you can enable additional sharing options in System Preferences. Typically, the left panel of a finder window in one machine will then show the other machine under a "Sharing" option (at least in OSX 10.5): double clicking it will enable you to sign in to share the screen or to access files. In this way, I think you you should be able to do anything on one machine using the keyboard and screen of the other for the price of a piece of cat 5 or 5e or 6 cable: you merely have to set the sharing correctly. If you want to connect 3 or more machines, you'll need a switch. If you want to use one and the same ethernet source for 3 or more machines, you'll need a switch and a router (though some pieces of equipment contain both switch and router). If you're going to buy a router and a switch, you'll need cable, too -- so why not be cheap, start with just one piece of cable, and see if you can get what you need by direct connection of the two machines?

Warning: I have a number of machines connected through a switch to a router with screen sharing enabled. My firewall on one machine causes some issues with connectivity (in some directions) that I haven't resolved yet. Also, screen and file sharing abilities are lost when I have an active internet connection through the ethernet port. IIRC: if I want to browse the web while using screen sharing, I have to connect my internet through a USB port on the machine I'm using while reserving the ethernet connections through the switch for screen and file sharing. You may have a similar problem with trying to share while connected to the internet, depending on your method of internet connection

[moggie]

2. Generally, that's a recipe for disaster

The disk has two ports so that you can daisy-chain other disks (and other non-computer Firewire devices), not so that you can connect it to two computers. The problem is that, when you attach a disk to a Mac, the OS expects to have exclusive access: it doesn't know that it needs to cope with data changing behind its back, or that it needs to cooperate with a second computer to avoid the two writing simultaneously to the same area. If you carry on this way, sooner or later (probably sooner) you'll have a corrupt filesystem, and will lose data.

The only way you can get away with doing this is by ensuring that only one of the Minis at a time 'mounts' the disk. Always unmount it on Mini A before mounting it on Mini B. This should be safe. But I still wouldn't trust it, because sooner or later you'll accidentally mount it on both simultaneously, and then you're at risk.

For sharing files, why not use the facility the OS provides for that, and share over the network? Attach the disk to one of the Minis, go to the 'sharing' preference pane, allow file sharing, and add the volume to the list. Provided you're running Leopard, you can even use the disk from Time Machine on the other Mini.

[ozymandius]

5. Great advice.

I've read more info about the subject and you clearly are spot-on with your advice. It sounds I would need a second router, other than the router that gates the data flow from the modem to the two computers. Is that a reasonable conclusion?

[moggie]

8. Could you clarify your network?

If I've understood correctly, you have a broadband router which has at least two ethernet ports, and both of the Minis plug into this. Most home cable/DSL routers which have multiple ethernet ports function as a network switch on the "home" side, with all those ports sitting on the same network. So the Minis should be able to "see" each other on the network, and you shouldn't need any extra hardware.

[ozymandius]

9. I'm sorry to have taken so long to respond.

We have a 4-port Dynex router. Ports 1 and 2 are dead. The two computers can see each other, however. I am just having trouble configuring sharing settings between the two.

[NoQuarter]

3. Are your Minis are Airport enabled?

The latest rev of the AP Extreme base station allows a USB drive to be attached and shared on the network. So you can pass files back and forth, plus backup as you do now - with less clutter as a bonus.

[ozymandius]

6. Unfortunately, no.

Only one is airport enabled. That is still a splendid idea.