Just wondering about SATA/eSATA

[arima]

Since eSATA is a relatively new way to connect external stuff to internal fast 3Gb/s ports, i was just wondering, if it can be used to connect 2 or more computers together. If so, how can it be done? Are there any special things i have to take note? :?

I have decided to build a separate computer just to store, instead of getting a relatively more expensive NAS system. It will run raid5 on 8 harddisks.

 

[evongugg]

You can add a removable hard drive with eSata, but not a computer.
If you have a computer you can share through your router or with a crossover cable connected between the two computers. You will need an two network interface cards on one computer and one network interface cable on the other to share with a crossover cable.
The you will need to create a network and share the drives.

 

[arima]

yea i know that. that was my original idea, but at 1Gb/s tops.. it just seems a little slow compared to the 3Gb/s SATA II is offering :lol:
Maybe there's someway to configure the controller to work like the controller in SATA hdds/ext cases.

 

[Iceblue]

How good are you at writing your own software?

SATA, SATA II (which officially does not exist; 3Gb is still SATA), and eSATA are intended for point to point connection between a computer and a mass storage device. The SATA cable does not carry station addressing capability. The cables are very short.

1000BASE-T is a LAN networking specification that is intended for connecting multiple stations of various functionality on a farily widely dispersed local area network.

Problems in using SATA for networking:
1) Cable length is 1 meter maximum (2 meters for eSATA) Compare that with standard Cat5 cable running 1000BASE-T: 100 meters.
2) It is point to point only, so your "network" would be limited to two stations, one at either end. Compare that with the very large address space of ethernet.
3) As mentioned at the beginning, you'd have to write your own drivers.

Hardly worth the trouble for the improvement in speed.

 

[arima]

thanks. that was very informative. i was going to just do point to point. And also, i think shielded SATA cables can take it further than 2M? By the way, i think i'll just need a maximum of 2m since the storage server is just going to be next to my desktop. If it can't be done, i might just get an extra 2 GbE cards and do load balancing.
Originally USB was also point to point if i'm not wrong.. But now there ARE USB networks, tho not very popular.

 

[Iceblue]

And also, i think shielded SATA cables can take it further than 2M?

Well, it doesn't go kapuie at 2.1 meters, but the specification is 2 m. Much longer would increase signal attenation, which would introduce read errors and the like.

By the way, i think i'll just need a maximum of 2m since the storage server is just going to be next to my desktop.

If all you want to do is connect to a nearby storage device, that is what eSATA is for. It will look like a hard drive, nothing more. But, if you have more than one computer plus your storage device, that is no longer point to point, because you now have 3 "points."

Originally USB was also point to point if i'm not wrong.. But now there ARE USB networks, tho not very popular.

That might be true for the original implementations on the market, but the specs included multiple devices. Even now, you don't see to many true multidrop networks done with USB, even for simple devices. That's why you see so many USB hubs on the market. SATA specs do not allow for multiple devices on a "network." It is assumed there is exactly one device at one end talking with one host at the other. Even the previous PATA allowed for two devices (master and slave) plus the host, but SATA is one device only.

 

[arima]

thanks again Iceblue, that was very helpful

 

[arima]

That's why you see so many USB hubs on the market. SATA specs do not allow for multiple devices on a "network." It is assumed there is exactly one device at one end talking with one host at the other./quote]

i think that may not be true for much longer. There are port multipliers for SATA. But right now, support isnt huge. and it works only with SATA II.

 

[Iceblue]

Well, we'll see where this goes. The SATA port multipliers are just that - port multipliers. They don't create a true multidrop network. For example, the drives are unaware of each other; they only know about the host. They allow you to connect multiple drives to one port, but not create a multiple device peer-to-peer network.

 

[arima]

yep.. understood. All that needs to be done is the development of some kind of communication protocol that works over SATA

 

[Guest]

hi
this is like the one thread out there, about this. I did come to the same conclusion, so I would like to ask if you know any programs, or at least something that could help bring this idea forward. I see the disads, but I still think that it would worth the try, but I need some sort of a starting point...
many thanks, hope someone can and will help
Z

 

[Neostim]

hi
this is like the one thread out there, about this. I did come to the same conclusion, so I would like to ask if you know any programs, or at least something that could help bring this idea forward. I see the disads, but I still think that it would worth the try, but I need some sort of a starting point...
many thanks, hope someone can and will help
Z

I too started thinking about this a few days ago, and this is the only thread I came across as well.

Even if someone could point me in the direction in what to research to begin writing drivers for this, I would be more then willing to try it out.

homer jay simpsons at hotmail DOT com