small SATA NAS controller?

b guy said:

An embedded platform offers quite a bit of work accomplished but trades size and a lot of unused circuitry. Is there a better solution ?

A forum like this is a bit biased towards embedded processors, so you are likely to hear mostly suggestion that the embedded solution is the best solution. For a small footprint SATA NAS the AM1808 would do nicely, as it has both a SATA interface as well as on board EMAC and runs Linux on its ARM making a NAS setup easy to implement as well as leaving the potential for expanded functionality. Of course it could go much smaller than 1U if desired, in fact 1U would be rather large for just one. I suppose what is truly the best solution depends on additional requirements, number of drives, performance needs, power requirements, etc.

I'm not opposed to using an embedded solution, especially if it really is the best all around solution. I was just curious if there was another way.

Of course the form factor could be smaller, in my case I'm using a modified 1u rackmount chassis but a smaller desktop unit would work. The end goal is to try and design an open source hardware solution for SOHO NAS units those of us so inclined can build for ourselves.

I'd like to run at least 4 SATA drives, gigabit ethernet or even dual gigabit, power is really not an issue - that's really the easy part. I need a linux or BSD variant capable of supporting software RAID, various file systems, etc.

b guy said:

The end goal is to try and design an open source hardware solution for SOHO NAS units those of us so inclined can build for ourselves.

You may want to look at the Hawk board, it uses the OMAP-L138 processor, which is similar to the AM1808 I mentioned but adds an on chip DSP. It is a board targeted at the open source community, so it is all open and low cost relative to other eval boards.

b guy said:

I'd like to run at least 4 SATA drives, gigabit ethernet or even dual gigabit, power is really not an issue - that's really the easy part.

None of the ARM processors TI has provide more than a single SATA port, though this can be dealt with using a port multiplier there may be a performance impact, and unfortunately none of the TI ARM processors have both SATA and Gigabit Ethernet. The OMAP-L138 / AM1808 is the closest we have with a 10/100 EMAC and single SATA port.

Well that's depressing, I really wanted to use a TI sourced solution on this. (I worked in a TI clean room back in college). TI chips just "work", especially from a driver standpoint.

I don't have one of they many commercial desktop NAS solutions to tear apart, just an older Netbook which uses 10/100 LAN and a single IDE disc. Based on what I've seen I had assumed most of the commercial systems were using fabricated solutions of one kind or another in place of a full blown SBC.  A component built solution would be interesting but is a bit beyond my current design skills, unfortunately.

That leaves me with a couple of options -

1. buy a desktop unit or two and reverse engineer them

1a. Figure out which supplier is building the controllers and source them (I wonder if I can talk 500 - 1000 people into building one of these?)

2. Find an embedded solution w/ Gigabit LAN and at least one SATA (I had planned to use an 8 port multiplier or a 4 port pci / pci-e SATA RAID controller anyway)

With the myriad of desktop NAS offerings I just had a feeling there was at least one basic 2 or 3 chip solution out there somewhere (basic processor, LAN and SATA controller  with a cheap power regulator).

It might not be the exact best place for promoting Marvell products, but since TI doesn't do anything really similar to this I will recommend you having a look at Marvells Kirkwood chips which you will find (running Linux) in many (if not most) embedded SOHO NAS devices... :-)

More info to be found at:
http://www.globalscaletechnologies.com/c-4-guruplugs.aspx
http://www.marvell.com/products/processors/embedded/kirkwood/

Good luck with your project
  Søren

I was looking for very similar functionality, e.g.: 4*SATA + ETH-or-SATA(towards a host)

1. I've never looked into Marvell portfolio, since usually the documentation is scarce and the chips are not so easy to purchase (in 10-20 pcs qty).

2. the 88F6281 looks attractive (there is at least a minimal manufacturer documentation), yet the whole famili has just 2 SATA ports per device.

Does anyone knows about SATA "multiplexer" chips (like a 4/8-channel crossbar switch)? I'm not looking for top performence SATA mux, but for high capacity one - the disks seektime is signifficantly longer then SATA transport, so for my goals, simple multiplexing would suffice.

Reverse engineering may not work most of the time. Start working from the scratch, take help form TI experts through this forum, definitely you will have what you wanted. You can look into other products to get some idea and price information. It may not give you complete solution