SAN solutions that speak 10Gb are pretty pricy! I'm not sure what your definition of "affordable" is.
Would something like the following work for what you are after?
- workstation 1 - normal workstation stuff + the large RAID
- workstation 2 - normal workstation stuff only
- 10GB copper NICs in both workstations
- new low cost NetGear 10GB copper 8-port switch ($999)
Sounds a lot better than the HP EVA P6xxx Storageworks solution, but somewhat more limited in storage space.
is there a way to build a raid-system (level 3 or 5) that ist accessible from two workstations AND affordable?
What speeds do you need to see at each client?
(Just "accessible" and "affordable" - no problem. "Accessible by multiple workstations at high speeds enough for a couple of layers of Epic 5K at 450MB/s" and affordable - not so much, probably $20K and up for a 10GbE based NAS like GB Labs Space.)
comparable with the speed of a typical Raid-3/5 System, ready for RED Epic 5K-Footage.
At the server level (direct-attached), it can be fast for not a lot of money, something like an 8-, 12- or 16-bay SAS expander with bandwidth in excess of 800MB/s. Sharing it however among two or more workstations is where things slow down and/or get really expensive. If you are looking at high bandwidth from the get go (e.g. 500MB/s to each workstation at the same time), then it should be something like a $20-40K GB Labs Space I mentioned above - or an even more complex and expensive SAN. If you're OK with speeds 250MB/s and below, Jim's advice may produce acceptable results; for speeds under 100MB/s, there is a host of COTS NAS solutions like Synology and QNAP, but watch out: few of those work well for high bandwidth apps like video editing.
For those wanting to check out the new 10GBE switch, here is the link. 10GBE is finally here for small business and the cards are $350 to $385 for the single port versions. There are NAS/SAN units that will handle the Intel 10GBE cards. Thecus is one of them. The other option is a storage server. Finally an affordable 10GBE solution for small business.
Thank you all for your helpful considerations! I think we will try the NetGear 10GBE switch.
I soon will post my plans of building a new workstation, can you guess what disk-speeds i need for a 250MB/s bandwith?