I suppose from the phrasing of your questions you have never tried to accomplish such a project. I think i serve you best in not only trying to answer your questions to my best knowledge but also raise the questions you probably should have asked. (Maybe you indeed have and my comments are superfluous - excuse me for estimating your level of expertise wrongly in this case.)

OK, stop here. First you should decide how you want the media to be served.

One way is a "shared drive" which you can "see" and use across your network. This is not a media-specific solution but a way to share files - in your case picture files and video files - over a network and have them physically stored in a central space. Depending on the OS of your clients you will need an NFS server installed (is maybe even included with the Ubuntu distribution, i don't know) and configured and maybe a SAMBA server, which does the same for Windows-clients if the don't know NFS (which is to be expected). Set up some access rights and connect the shared drive(s) to the client computers and you are done.

This solution is quite "low-tech" and won't accomplish some of the more exotic applications in modern media technology, but it is easy to install (1-2 hours for an knowledgable person) and very low on maintenance (next to nil).

The next variant is a streaming server for the videos. You can use vlc, a freeware video player, to accomplish this for the videos. For the photos you can use a web server (Apache, ...) with some logic (a few CGI-scripts will probably suffice) behind to automatically generate web pages from (newly added) photos.

For a generally knowledgeable person without specific knowledge in this area the effort to create this is 1-3 days. You need to set up the server, configure the web server, write the scripts and install and configure VLC to do streaming video. You have nothing to configure on the clients (maybe install VLC as client for the streams if you don't have any other software for this) as all the media will be served via web technologies. You simply "surf" to a web site which happens to be in your local network.

You can make this even more complex by adding video-on-demand features, authentication (probably based on a RADIUS server), some web content/application management (from very basic up to the enterprise level IBM WebSphere and every size in between), VoIP features (using RTP / SIP), etc., etc., and the projected effort to do so can range from some days to several hundreds of man-years (have a look here they are doing exactly this, i worked for the project some years ago).

Now i am fully aware that this last part is perhaps way to big for your private purposes, i just wanted you to know what you can do and decide where you stand in this.

Good idea. Btw., you only need a mirrored disk where data can be lost. Mirror your data disks but leave the system disks unmirrored. In case this crashes you can simply reinstall the server from scratch. In professional environments system disks are always mirrored, but only because the machine would be down when you reinstall. Failing disks which are mirrored can be changed and resynchronized online this way foregoing the downtime. In your case it won't matter if the server is down for a day or two.

Still, you need a regular backup for that server, because even mirrored disks can (and will, over time) fail. If you put all your data into one place you should make damn sure you do not lose this place, because it will mean everything is gone. Don't only take disk failures into consideration: what about a lightning (flood, whatever) wiping out your machine - would you like to lose you data then?

Backup media tend to deteriorate as well as disks do, btw. Take a tape backup, put it into a safe for 10 years - chances are you can't read it any more even if you still have a working tape drive to do so. Big tape libraries regularly rewind and retension their used tapes automatically so that this doesn't happen. You will perhaps not buy some file cabinet with a roboter so you will have to take care for this yourself.

The same goes for DVDs: burn them, store them for some years and one or the other probably has failures.

Whatever you use, set up mechanisms to check on the quality of your backup at regular intervals and create a new backup set from time to time (say, once a year or so).

Igitt! Suppose you do so: you connect two (three, four) disks to your server. You have some central chassis with 2 (3, 4) cables and disks connected dangling from it. The system is probably located in your basement, next to the router, etc.. Now send one of your kids to fetch something from the basement - chances are they trip over one of the cables, ripping the disks from the connectors, most probably causing head creashes, ... You want that? You want to take chances?

Do yourself a favor and use a ("a" as in "one") firm casing for the disks. Ideally the case of your system allows many internal disks, but even if not: go for "the sturdier the better" and "the less cabling outside the better". Typically i would have suggested SCSI disks and a Fast-Wide-SCSI controller onto which you can connect up to 15 disks per channel. I know, SCSI disks are expensive and there are other technologies (SATA, multi-port IDE controllers, ...) which probably will do what you want at a considerably lower price. I am not that knowledgeable in consumer technics and if noone else answers you will have to investigate yourself. Ask around in hardware shops (and, at all rates, buy there once they consulted for you - if you first let them do the work then go to the next box-shifting hardware supermarket you will help drive out of business the hardware shop who just helped you) and let them show you the options.

That depends on a lot of thing, mostly the number of users: in a household you may have 2-3 users max at the same time, probably max. 2 will use streaming at the same time. A halfways modern PC with sufficient RAM (i suggest 4GB min) will effortlessly cope wiht such a workload. The bottleneck will probably be the WiFi router because the backplane of these consumer pieces is not the fastest at all. Still, i think it will suffice.

I hope this helps.

bakunin