ESATA HUB or PORT MULTIPLIER FOR REDSTATION

[Nir Shelter]

In preparation for Redstations/SSD I want to tailor my inputs to fit E-Sata.
Am currently using an E-Sata connection Raid 1 box by Stardom with my MBP through an E-Sata to express card34 adapter great throughput and very reliable.
I connect the Reddrive via FW800 (no bus power FW cable) but soon enough Redstations will connect with E-Sata. I also have a bunch of client HDD that have an E-Sata connection that I rent to clients.
So I want to get an E-Sata hub that will allow all drives sending and receiving to connect via E-Sata. Does any one have experience with an E-Sata hub they can recommend?

Another alternative would be to get a Sohotank ST5610 which is a port multiplier. It can connect via E-Sata and give access to 4 independent drives:
http://www.stardom.com.tw/sohotank_spec.html

Then at the end of the day you can pop one of the drives downloaded to into an iTank enclosure, as they use the same bracket, to deliver to the client:
http://www.stardom.com.tw/itank_feature.html

What are other solutions are people looking at?
Nir.

 

[Alexander Ibrahim]

http://www.bhphotovideo.com/c/produ...42P_Tempo_SATA_ExpressCard_34_Controller.html

http://eshop.macsales.com/item/Other World Computing/MEQX2KIT0GBO/

http://eshop.macsales.com/item/Sans Digital/TR5MB/

 

[Dustin Cross]

I have a couple of these eSata Port Multipliers.

http://www.addonics.com/products/host_controller/extpm.asp

Work fine for connecting five drives per port to an eSata controler that supports that, like the Sonnet cards, but you are limited to the bandwidth of a single eSata port. So instead of each drive getting 3Gbps, all five drives share 3Gbps. That usually enough to connect or three devices before you max the bandwidth.

Dusty

 

[Alexander Ibrahim]

I have a couple of these eSata Port Multipliers.

http://www.addonics.com/products/host_controller/extpm.asp

Work fine for connecting five drives per port to an eSata controler that supports that, like the Sonnet cards, but you are limited to the bandwidth of a single eSata port. So instead of each drive getting 3Gbps, all five drives share 3Gbps. That usually enough to connect or three devices before you max the bandwidth.

Dusty

Exactly true.

In a RAID 5 situation though, there is significant overhead on the hardware enclosure as some of the drives speed is eaten up by parity writing.

That is the big difference between a smart RAID enclosure like the 4 bay OWC QX2 I linked above and a dumb one, like the Sans Digital.

The Sans has to have its RAID managed by the controller or the host computer- so all that parity bandwidth is passed over the eSATA link.

The OWC has a RAID controller on board... so you just write to it as a single big volume, and it handles all the RAID parity throughput.

What's that mean in practice? A 4 drive RAID 5 array uses 25% of its bandwidth writing parity bits. So ... its roughly as fast as a 3 drive RAID-0, which can just saturate a SATA 3Gb link.

So, in the use case of a 4 drive RAID 5 the OWC case will be 25% faster than the Sans Digital case. The downside is that the OWC case will be better able to keep the drives busy all the time- so they'll have shorter lifespans, while the SANS case will keep drives idle more... because they'll be waiting on write data over the eSATA link.

For my purposes I'll be buying in a G-Technology 4 port eSATA RAID controller. I'll buy in two of the OWC case and set them to RAID 5 with 2TB drives, then use the Controller to stripe them, creating a RAID 50 nested array.

I'll buy in a SANS 5 bay and use it in a JBOD mode. I still have homework to do and determine if they really mean JBOD or if they use "JBOD" to mean concatenation/spanning.

 

[Nir Shelter]

Raid boxes aside each one of my MBP based data download stations (and I am guessing anybody else) has 2 e-Sata ports available as the express card 34 slot adapter has only 2 ports. One is used to connect our storage (raid or not) and one will be used to connect the Redstation but we will also need one more for client HDDs. So either an e-Sata hub for multiple e-Sata connections or port multiplier box with multiple HDDs will have to be the way to go.
Wondering what are most people looking at and whether anyone has experience with good e-Sata hubs?
Hubs obviously being a cheaper solution

Nir.

Edit:
Sorry I didn't see the link in your post Dusty thanks for that.
How are you using this multiplier? Do you use it with a laptop and external HDD or with your Macpro? Does it need a controller card or can it act as a hub independently?

 

[Alexander Ibrahim]

Raid boxes aside each one of my MBP based data download stations (and I am guessing anybody else) has 2 e-Sata ports available as the express card 34 slot adapter has only 2 ports. One is used to connect our storage (raid or not) and one will be used to connect the Redstation but we will also need one more for client HDDs. So either an e-Sata hub for multiple e-Sata connections or port multiplier box with multiple HDDs will have to be the way to go.
Wondering what are most people looking at and whether anyone has experience with good e-Sata hubs?
Hubs obviously being a cheaper solution

Nir.

Edit:
Sorry I didn't see the link in your post Dusty thanks for that.
How are you using this multiplier? Do you use it with a laptop and external HDD or with your Macpro? Does it need a controller card or can it act as a hub independently?

I see your concern... and I really have to ask why you don't want to use the Firewire 800 port?

The total bandwidth of ExpressCard eSATA is typically around 200MB/s, with the better ones hitting 250 or so.

Instead of splitting that 3 ways, it would be smart to use the 100MB/s FW800 interface for part of the work.

If Firewire is not an option though, then a port multiplier makes great sense. I've used the one Dustin linked, and its been reliable- I'm considering buying one for myself.

 

[Dustin Cross]

Alexander,

His problem is he only has two eSata ports with his laptop. He needs more eSata ports to connect all his eSata devices. Sharing the load across eSata with PM should still be faster than putting more than one device on the Firewire bus. Firewire maxes out at around 80MB/s and like you said a good Expresscard eSata card maxes around 250MB/s. Using both is the best option.


Nir,

As far as I know, there is no eSata hub, only Port Multipliers like I linked to. I could be wrong, but I don't think so.

Port Multiplying (PM) is part of the eSata spec. Some cards support it and some don't. The Sonnet Express34 eSata Pro cards support PM. Their four port desktop card also support PM. Just check your card.

I use the box I listed with my laptop and with my desktop. Just depends on the situation. Mostly with my laptop though, because I usually have plenty of eSata ports in my towers. It is better to have a dedicated eSata port for each device, but that isn't an option with a laptop.

Hope that helps.


Dusty

 

[Alexander Ibrahim]

Alexander,

His problem is he only has two eSata ports with his laptop. He needs more eSata ports to connect all his eSata devices. Sharing the load across eSata with PM should still be faster than putting more than one device on the Firewire bus. Firewire maxes out at around 80MB/s and like you said a good Expresscard eSata card maxes around 250MB/s. Using both is the best option.


Nir,

As far as I know, there is no eSata hub, only Port Multipliers like I linked to. I could be wrong, but I don't think so.

Port Multiplying (PM) is part of the eSata spec. Some cards support it and some don't. The Sonnet Express34 eSata Pro cards support PM. Their four port desktop card also support PM. Just check your card.

I use the box I listed with my laptop and with my desktop. Just depends on the situation. Mostly with my laptop though, because I usually have plenty of eSata ports in my towers. It is better to have a dedicated eSata port for each device, but that isn't an option with a laptop.

Hope that helps.


Dusty

I understand the constraint... here is the thing.

That's 250MB/s TOTAL bandwidth for the controller. Not per port. Total.

Its a limit of ExpressCard not eSATA. Expresscard is limited to 2.5Gb/s, which is a theoretical 313MB/s. Once various inefficiencies happen, you get less as we've already agreed.

Split it across 3 drives and they are all running a maximum of 83MB/s. In practice with switching overhead, they will run slower.

Hence my suggestion that he consider using FW800.

 

[Nir Shelter]

Thanks Dusty will do.

Hi Ibrahim.
True my devices will be sharing the total bandwidth of the express lane but as you said via the E-Sata ports I will probably have around less overhead 250MB p/s. I normally work with one source media input and 2 backup destination (one being a raid1) outputs this means a 3 way split 250/3= 83.33MB p/s max per device >FW800 which is ample for most HDD to handle. Soon enough with Redstations and SSD on the cameras becoming more common I would rather use e-Sata ports for all inputs and saturate the express lane on the MBP than slow it down with one device connected at max less over head ~74MB FW800.
Will tryout the PM with my Si adapter but I may have to get a Sonet card from the US as they seam to not be readily available here in OZ.

 

[Alexander Ibrahim]

Thanks Dusty will do.

Hi Ibrahim.
True my devices will be sharing the total bandwidth of the express lane but as you said via the E-Sata ports I will probably have around less overhead 250MB p/s. I normally work with one source media input and 2 backup destination (one being a raid1) outputs this means a 3 way split 250/3= 83.33MB p/s max per device >FW800 which is ample for most HDD to handle. Soon enough with Redstations and SSD on the cameras becoming more common I would rather use e-Sata ports for all inputs and saturate the express lane on the MBP than slow it down with one device connected at max less over head ~74MB FW800.
Will tryout the PM with my Si adapter but I may have to get a Sonet card from the US as they seam to not be readily available here in OZ.

Your math is off.

FW800 peak theoretical throughput is 100MB/s.

Practically speaking you can get 80MB/s sustained.

For eSATA over PCI Expresscard, 250MB/s is the peak throughput of the card.

As you add devices it will become less efficient. You are rather unlikely to get 80MB/s with three devices. Write performance will typically be slower than read performance.

For 2 drive setups eSATA is definitely faster.

For 3 drive setups, like you describe, 2 eSATA and a FW800 is usually faster.

I recommend using the FW800 for read only, and writing to the two eSATA devices.

If we were talking about a desktop with a x4 PCIe card, its a no brainer- eSATA is much faster everyday.

Of course... I wouldn't make any moves at all now. With Lightpeak, or Thunderbolt, about to be released a single eSATA to lightpeak bridge will likely support up to 3 full speed eSATA II drives- and still have a couple hundred MB/s to spare.

The MacBook Pro is about to become a MUCH more capable RED DIT/Ingest station.