I have just bought a Rosewill RSV-S5, I have installed 5x1,5Tb Western Digital Green disks in it. After that have I created a Raid5 on them all with the software that followed with the hardware. Not the raid it self works fine, but it is SLOW, I can only obtain a maximum of 25 MB/s, and if SABnzbd+ is downloading with 5 MB/s is it having a hard time streaming a normal DIVX (700 mb) movie. Is this normal or is there something wrong?
Edit: should be able to handle 3 Gbps = 384 megabytes / second
Edit 2: 
As you can see am I only downloading with 3,76 MB/s and I'm trying to watch V s02e08 (720p), but it is completely unwatchable, as I can see 30 sec, and the it buffers for 20 sec.
Edit: Other information there might be required
I'm running Windows Server 2008 R2, optimized for program performance. Windows is installed on a 60GB SSD. I have a 50 Mb/s internet connection and a 1 Gb/s LAN, all connected with Cat6 Ethernet cables. The MCE is using a Gigabyte EP35C-DS3R motherboard with 2 GB DDR2 ram.
Edit 3: I have used chunk sizes for 128 KB
Edit 4: I found this on newegg
Pros: Enclosure for 5x2TB hard drive is fine. This is basically a rebranded San Digital TR5M-B product. For support Rosewill tells you to contact San Digital. No direct support from Silicon Image for the computer raid card.
Cons: Includes computer Silicon Image 3132 raid card, extremely slow raid 5 write (our tests ~10MB/s). Compare to regular internal local drive write 30-60MB/s. We basically dumped the Sil3132 card and replaced with High Point RocketRaid 622 card for extra $69.99. Note for RR622, turn off ECRC (end to end CRC check) for card to work on IBM xserver. What took 12hrs to copy now took 2-3hrs. San Digital realized the problem and has the newer model TR5M-BP TowerRaid Plus that comes with High Point RocketRaid 622 card. Rosewill should discontinue this product and go with TR5M-BP. Could not get Silicon Image raid management software to work with complicated 2008R2 server with 10 NICs, application doesn't know how to talk to localhost port with all those NICs. No updates from Silicon Image and support from San Digital ignored. Gave up on Sil3132 card. Save yourself from a lot of headaches, get the RR622 card too if you are going to buy this product.
Other Thoughts: The newer model is TR5M-BP TowerRaid Plus, comes with High Point RocketRaid 622 raid card for the PC instead of Silicon Image Sil3132. According to San Digital, raid 5 performance for Sil3132 read 80MB/s write 19MB/s, and RR622 read 154MB/s write 149MB/s. Our RR622 tests gave (8TB raid 5) write ~80-110MB/s copying 40GB file took 8mins.
So I have now ordered a HighPoint RocketRAID 622 2P ext SATA III and hopes that it will solve my problems.
Gone to the mattresses with the RocketRaid 622 card, I really wanted this to work. See my previous 2 newegg posts.
First I wanted a cheap, reliable, and fast storage device to backup Hyper V images. This seems to be the solution but ran into problems. In RAID 5 with the silicon image card 3132, device was very slow and sometimes doesn't work (I think the service prog can't communicate with Java management app when you have multiple Nics). So first dumped 3132 and got High Point RocketRaid 622 card.
622 was fast but kept disconnecting. Told to get the more expensive TLER, Time Limited Error Recovery, enterprise drive. So got WD RE4-GP, WD2002FYPS (I only trust WD), make sure it's on 622 tested or certified list. It still disconnects and hang server. When this happens, can you trust what is copied? Told to disable caching but made it really slow, less than 10MB/s. I have more than one 622 and esata cable so not bad card. Had the latest firmware and driver. Esata cable short, less than 3 feet.
SECRET SAUCE:
To make it work, jumper the sata drives to 150. Data transfer still fast (I think around write 70+ MB/s and read 100+ MB/s) and no disconnects. Only tested it once over night transfering 1TB over GB network to IBM DS3300 ($10,000 device). Need further testing, 2008 R2 64bit server. Don't be fool in your tests because Windows copy things into memory first. Transfer speed you see is the speed to copy it to memory. Open task manager and then resouce manager, take a look at disk activities and you will see it still copinig to disk after your copy window close.
Get the version with 622 card. This is a Sans Digital rebranded product so buy the Sans Digital product. If you set it up as JBOD, software raid, the CPU will be doing all the work (not good). Hope this is the last of the problems.
Thank does indeed look very slow, although you've consciously bought slow disks and R5 isn't the fastest configuration your should be seeing significantly better than 25MBps, even for random reads. Have you spoke with the manufacturers?
Given this question is more about generic hardware rather than being server specific would you like me to move it over to our sister site superuser.com who may be able to help more?