Do I really need a SAS expander?

[systemlayers]

Hi still working around what I need for a major media server upgrade.
(yes this is a second thread to one a while back I apologize for my n00bness)
So far this is what I've worked out:
I have a budget of about 3000
mobo: ASUS E35M1-M (I don't need much power it's just a file server)
case: Norco 4220
drives: hitatchi 7K3000 2tb x 8 (for now)
replacement fans: Noctua NF-R8 x 4 (I hear the norco has screaming fans and this server will be close to my home theater system)
raid: areca ARC-1680IX-24-2G
power supply: corsair vx450

I have a couple of questions as i'm pretty new to this (my current server is an old atom with pci sata raid card).
Do I need to buy mini-sas cables for the areca? I can't tell from the specifications if it just comes with sas-sata cables.
Can i get by with the norco backplane? Or should I really go for the HP sas expander which seems popular here. Why do i need a sas expander?
If i did have to go sas expander i assume that would be another pci-e slot and I couldn't go with the low power AMD solution.
Any other solutions or better components on my budget (i want to maximize file space I have 400+ dvds, many of those damn-large 5D2 files and some blu-rays to backup).

 

[sub.mesa]

You forgot to mention the OS for your build; that will change everything.

If you choose UnRAID which only accesses one drive at a time, then Expanders should be a logical choice since they would not lower the performance in this case. In other cases, especially when using ZFS, you may have reason to avoid using expanders; to avoid lot's of headaches/problems, to avoid performance issues and to avoid buying expensive hardware that has a limited useful lifetime.

Your controller already includes an expander (iX) i believe, so i'm not sure if this would work and if so what performance penalty there would be. Two chained expanders sounds extreme to me; this for sure would not be my recommended setup, but i'm more critical about the user of SAS expanders than other people are.

Why 7K disks instead of 5K? Are you storing large files, mixed or mainly small files? Most media servers only store large files, and as such low rpm + high data density is what you need. That would achieve the higher performance against the lowest idle power consumption and thus heat generation.

 

[systemlayers]

I have a copy of windows 2003 server standard atm which i'd be transferring to the new build I think. Don't really want to go through more pain with switching to linux or something.
Well I was thinking the samsung 2TB drives which are cheaper but there was some question on how well they work with areca controllers and I know the hitatchi's are well established raid drives.
I'm not looking for much performance. Just enough to drive 2-3 tvs + full HD rips and perhaps video encoding at the same time (max).
Ok I might actually have been wrong in my assumption of what a sas expander does i'll have to read some more. For some reason I thought it was for attaching to the backplanes of the drives or something. But it's for peripheral devices correct?
Thanks for the help.

 

[unwire]

Hitachis are pretty good for RAID setups.

A SAS expander is essentially a port multiplier. It takes one SAS port as input, and gives you a bunch more. Since SAS ports on the actual RAID controller card are generally expensive, this gives you a way to add ports more cost effectively, as well as relocate them in another chassis if need be.

 

[nitrobass24]

You dont NEED a SAS Expander.

The reason to get a SAS Expander is to save $$ now and in the future when you upgrade your Controller.

1880ix24 - $1200
1880i + Expander - $900

You basically get the same setup for $300 less. When the Areca 19xx comes out you can buy just the i or x version for $5-600 and still use the expander for 24 ports.

Also Expanders are typically a component on RAID Controllers that cause compatibility issues with drives, backplanes, etc.
The HP is well tested regarding compatibility issues with the equipment listed above (except for the mobo, some mobos do not properly negotiate the proper power signals, but most do).