What I am seeking is input on this.
Cost effective (the people want cheap) solution to increase server storage space with as little impact on throughput (what I want) as possible.

The situation is this:
I have a server that sends instructions to 20 clients to perform certain tasks. The clients send gigs of data back to the server for storage.

BACKGROUND INFORMATION
Network: Gigabit Ethernet
Clients: (20) HP, Solaris, Linux
Linux Server: Dell R805 PowerEdge (QUAD Core Athlons 16 gigs of ram, 4 gigabit ports.

Selected directories are mounted (NFS) by clients.

One directory to be mounted by the clients contains executable files.

Mount commands are sent from the server (rsh) to the clients. Yes I know (ssh) but this is how the software was originally written so let's go with it.

The clients then receive commands to execute the binaries contained within the mounted directory.

The binaries basically create an image of the clients filesystem including special applications.

The client then sends the files and directories to the server which stores this “image”.

This process can be reversed to restore a client to the initial baseline image.

NETWORK AND STORAGE
In a nut shell, 20 clients are sending gigs of data to the server for storage. I need to attach a NAS (gigabit) to extend the storage capability of the server. The server would mount (NFS) to the hard drives on the NAS. The NAS, configured as a “direct attached storage” device (DAS), means the storage device is connected directly to the server and not the network (which makes it a DAS). This would provide direct storage expansion for the server. However, this configuration cannot be a bottleneck that significantly hinders performance.

Clients <---data---->Server<----storage---->DAS/NAS

QUESTIONS:
1) Will a low end NAS (gigabit port) work? (NetGear 1TB ReadyNAS Duo, RND2110-100NAS)
or something with a higher rated throughput (QNAP TS-239 Pro II)

2) Low end won't work, go with …?

3) Does the processor on the NAS play any role that would determine the performance of this configuration given that the server would mount directly to a directory on this device (DAS/NAS)?


Thanks,
Troy

Forgive me if I missed it, but you never seem to address the most obvious question...why can't you just put bigger HDDs in the server? Certainly that is the cheapest option possible, and could be done with minimal downtime if planned well.

My apologies for the omission...
The server is limited to a 2.5 inch 500 gig maximum size hard drive. (2 x 2.5 RAID 1). While upgrading to this size is a big step up in capacity, it is ultimately insufficient. The server only has two drive bays with no expansion by adding additional drives possible. Our only option is some type of external storage.

If you have a empty PCI(-e) card slot left I would put in a eSATA card and just buy cheap external enclosures with eSATA.

If you still decide to go with a gigabit NAS check out http://www.smallnetbuilder.com/compo...nas/Itemid,190 for NAS speed charts.

Whatever you do don't go with USB since it's the worst external interface for fast data transfers.

Thanks for the recommendation. I am a developer who has been tasked to find an alternative to upgrading our XioTech Magnitudes 3000s at a cost of nearly $30,000. So, a network/server admin I am not but learning fast. I should have this down in another 1000 years or so.

Another way....
iSCSI.

Basically built your own...
Get a machine, attach required amount of storage space.
Use one of the gigabit ports,(or maybe bond 2) direct into the (lets call it) disk server.
Setup iSCSI, and there you have it

If you like and can get one of those fancy network cards with the extra hardware designed to offload some of the iSCSI protocol (iSCSI HBA)

In that case, I would second the suggestion for eSATA. You can get an eSATA drive array with built-in hardware RAID and just plug it right in (assuming you have eSATA, of course).

Personally I would avoid trying to add capacity via NAS on a production server. It might work fine most of the time, but there are just too many things that could go wrong.

While I build my own stuff for private use all the time, I would never recommend building anything for commercial use. If there's any sort of support issue, it can get very messy. Buy a box from a commercial vendor along with a support package and in the event of problems, solace is a phonecall away.