Cheap storage

Right now it's SATA. If you're running RAID (and you should), SCSI isn't going to buy you much more reliability. It's not going to give you much more speed on the low end either. Anyways, this is about cheap.

You have a PC with slots in it. It's going to be your server. I suggest having the OS on a RAID1 mirror. Don't have data on this so the OS can go as fast as possible. The RAID buys some reliability. If it's IDE, no slaves. Just masters. Mixing them slows things down quite a bit. Ok, you can put the CD/DVD on it.

Get a 4 port SATA card. You do not care about the RAID in it. Most of them are really software RAID anyways and each card does it differently. By doing software RAID, you can use any adapter. Hardware RAID means your data is at the mercy of a brand or even model of that card if it fails. Besides, you're going to be running an iSCSI SAN or an NFS/Samba file server here. Your CPU is dedicated to storage. Your bottleneck will be gigabit ethernet to your clients.

Get 4 SATA drives of the same size. I like to have a standard size that will be available in the future, like 500GB.

Now the hard part: how to power and cool them? If you have a case like the Antec PB180, there's a fan and a 4 drive chamber. Just get some SATA cables and maybe some 4 pin to SATA power adapters.

If not, you need to get an external drive. There are some nice ones under $150 with power and cooling for 4 SATA drives. You can also build your own with a PC power supply, a fan, power adapters and something to bolt the drives to that the fan pulls air through.

Now get some long SATA cables. I've used 42" ones. They do not have to be eSATA. I've used internal SATA from the drives through a card slot to the internal SATA card and they work fine. Using short SATA extenders lets you have a nice disconnection outside the PC or drive case.

Hook it all up, install your OS and make it a software RAID5 setup. Cheap.

Which OS? Do you want a NAS or SAN device? I really like ZFS on my servers and that means Solaris right now. Solaris 10u3 doesn't have an iSCSI target so that means NAS only. Newer versions of OpenSolaris have iSCSI targer. Linux has an iSCSI target also and I don't think it's as close to bleeding edge as OpenSolaris, but there are many that feel comfortable with it. There's a linux distribution called OpenFiler that does iSCSI target, Samba and NFS with a web admin interface for you non unix types.

Speeds? On a Dual PIII 500MHz I got 20-25MB/s. On a Xeon 2.4 or on an AMD 4000+ I get about 120MB/s. The PIII can't keep up with Gigabit. The other 2 can do 90MB/s over gigabit. That's faster then local disk on older systems.

4 * 500GB @$120/ea -> $480 for disk. Put a $500 PC with gigabit ethernet under that and you have 1.5TB or RAID5 for under $1000.