Do the e-SATA ports support Port Multiplier?

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johannes
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Re: Do the e-SATA ports support Port Multiplier?

Post by johannes » 05 Dec 2010, 06:38

Reply for B3: Yes1
/Johannes (Excito co-founder a long time ago, but now I'm just Johannes)

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 08 Dec 2010, 16:25

johannes wrote:Reply for B3: Yes1
So this does support a 4-bay enclosure then? [4x2TB] drives mapped as one 8TB single volume?

I just want to be certain of purchasing the correct enclosure [also looking at the Sans Digital enclosure mentioned above] and the correct "plug". I don't need problems afterward of return shipping costs, etc. Thanks!

johannes
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Re: Do the e-SATA ports support Port Multiplier?

Post by johannes » 09 Dec 2010, 03:25

Ok, to clarify. The hardware supports port multiplying but we haven't tested, so we can't promise that there aren't low-level software limitations that prevent this from working. HOwever it's an interesting question so we'll order such a device today and test this asap. Give us a few days and we'll get back with results.
/Johannes (Excito co-founder a long time ago, but now I'm just Johannes)

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 12 Dec 2010, 11:06

johannes wrote:Ok, to clarify. The hardware supports port multiplying but we haven't tested, so we can't promise that there aren't low-level software limitations that prevent this from working. HOwever it's an interesting question so we'll order such a device today and test this asap. Give us a few days and we'll get back with results.
Thanks! If it doesn't support port multiplying, are there other options such as LVM or symlinks that would for all pratical purposes read a 4-bay HDD enclosure as a single volume? I'm looking at a 4-bay enclosure with 4X2TB drives in it.............I could span the volumes as one drive or leave it at 4 individual drives for all my media, but would need a symlink or LVM on the B3 to read all 4 drives as one. I don't want to have to navigate 4 drives from my networked media player. That's the purpose of doing this.

albert
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Re: Do the e-SATA ports support Port Multiplier?

Post by albert » 12 Dec 2010, 17:40

If a port multiplier doesn't work, then you only can add one extra Sata disk.

What the port multiplier does effectively is multiplexing all drives on one port, that internal port controller needs to de-multiplex the drives and deliver it as separate drives to the OS. That's the reason why it only works as the internal hardware supports it, it needs to know what to do with the multiplexed data.

It also means that you're pushing al (multiplexed) ports through one Sata channel. Since disks only do around 120 MB/sec or less, and the hardware on B3 is Sata2, this wouldn't be a huge problem.

Going back to your story, if the port multiplier does not work you'll only see one disk of your 4 port array, so you'll be out of luck. LVM etc are running on top of the underlying disk hardware.

I am very curious if it actually works, so I'm looking forward to Excito's experience.

Albert

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 13 Dec 2010, 17:02

Thanks for the info.I do realize that the host [B3] must have a port multiplier in order for it to "see" my 4 bay enclosure on the eSATA port. It's unfortunate that most of the devices for port multipliers rest with PCs, either with a built-in adapter or an add-on adapter, but the balance of devices are not being manufactured with a port multiplier. I guess most people are stuck with either a 2TB [now 3TB] limit on one HDD, or most daisy-chain external HDDS/enclosures in their environment, something I don't want to do.............which brings me to this question.

Since LVM runs on top of the disk hardware, and I'm not able to use it, I guess I'm stuck with USB ports to transfer my data........now would a USB connection to a multi-bay drive be able to be seen by the B3? Would I be able to use LVM or symlinks? Could/would I have to span/JBOD the disks before-hand?

Currently, I have a couple of dual bay enclosures spanned as JBOD with 2X2TB drives as one volume [4TBs], going through my PC [port multiplier built in on the mobo]. I had to use GPT because of the limitations, and I know there's still a 9+TB limitation on GPT. I'm using 2 enclosures for backups.....each with 2X2TB HDDs as one volume in each [4TB]

What I'm trying to do is to use the B3s ports for my media, both on my NAS boxes and the enclosures I'd like to buy for the B3 [if I get the B3]. I have approx. 6TB on 2 NAS boxes now, but don't want to buy another.............If I could even get away with using the 2 USB ports on the B3 with multibay enclosures and perhaps a hub later on, that would be fine, but I'd like to have the B3 read all the drives in each enclosure as one volume, so as not to jump through 4 HDDs in each enclosure.

I'm not very familiar with Amahi http://www.amahi.org/ and one of the features of it that uses Greyhole http://greyhole.pommepause.com/ but this could be another option being I choose the right hardware [B3, Marvell Plug Computer, etc.] or if it will work at all............I have to read up more on that.

I'm also curious to see what Excito does with this, however I'm not too optomistic with the eSATA solution. If I could use the the 2 USB ports with the configuration I want, I'd be just as happy. For me it's not a matter of speed, as I will not be using the B3 or whatever I purchase for anything more than networking my media. My NAS's handle all my other jobs. I appreciate your reply.

Ubi
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Re: Do the e-SATA ports support Port Multiplier?

Post by Ubi » 14 Dec 2010, 00:59

LVM over USB sounds like a data integrity nightmare, even if it was possible. :)

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 14 Dec 2010, 05:25

Ubi wrote:LVM over USB sounds like a data integrity nightmare, even if it was possible. :)

Have you any suggestion as to what I should use then? I've read on some Linux sites that one is able to use [at least], a single USB external/enclosure HDD with LVM, but running some command lines before unplugging the device would alleviate any problems. Would symlinks be a better alternative? Thanks!

tor
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Re: Do the e-SATA ports support Port Multiplier?

Post by tor » 17 Dec 2010, 08:49

Hi all,

I have no done some initial testing with B3 and port multipliers. We bought an stardom sohotank http://www.scsi4me.com/stardom-sohotank ... osure.html which has both esata port multiplier and usb 2.0. Over usb enclosure services are used to multiplex access to the drives.

Using USB this device functions properly and each device/disk in the casing shows up nicely in the disk manager at B3. Thus scsi enclosure services are working fine on B3. Which means that devices like Drobo and alike would work fine.

Unfortunately we weren't that lucky with the esata connection. B3 detects the link and tries to access the unit. It further more discovers that this is a multiplied device and tries talking to it in that way. But we receive no reply.

This does not mean that no port multiplier devices will work. The port multiplication can be done in two ways Command Based Switching, CBS, and FIS Based Switching FBS. Our sata controller only supports FBS mode.

Most likely the casing above uses CBS mode which is why its not usable.

I will try to debug this further to make sure that this is really the problem.

In the meantime i would really like to hear if anyone has a port multiplier that works with B3?

/Tor
Co-founder OpenProducts and Ex Excito Developer

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 18 Dec 2010, 18:30

I looked into some enclosures that do support FIS Based Switching, and there are a few available, but I'm hesitant in buying more devices that may or may not be compatible with the B3. I'm now looking into purchasing a USB to Ethernet adapter instead, and have already made some enquiries to a few vendors. Seems like this will do the trick at a much lesser cost as well, but thanks for taking the time in doing your testing......at least some people will be aware on what hardware to buy.

albert
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Re: Do the e-SATA ports support Port Multiplier?

Post by albert » 19 Dec 2010, 04:58

Any idea of this external port multiplier is going to work?
Would be nice to see if excito could test this.

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

Albert

purple mink
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Re: Do the e-SATA ports support Port Multiplier?

Post by purple mink » 19 Dec 2010, 09:04

@albert. That's not really the problem, as well it's a little redundant since there are HDD enclosures that already have port multipliers in them such as this one from Sans Digital http://www.sansdigital.com/towerraid/tr4mbnc.html . As you will notice in your link, under the Product Features it reads "Compatible with any PM compatible Host Controllers." It's the source [the B3] that also must provide an eSATA host controller, as you notice in the picture of your link connecting it to an eSATA controller adapter in the computer. Mind you, Johannes has already confirmed that the B3 supports PM, but tor does mention this in his last post......
This does not mean that no port multiplier devices will work. The port multiplication can be done in two ways Command Based Switching, CBS, and FIS Based Switching FBS. Our sata controller only supports FBS mode.
I've already seen some HDD enclosures that support FIS, an example is here http://mediasonicinc.com/store/product_ ... cts_id=150 as it says under the specification tab, "Important Note: When connecting via eSATA interface, customer's computer hardware needs to have Port Multiplier w/ FIS-based switching in order to access multiple HDDs simultaneously." So something like this may work with the B3, but I'm not about to shell out cash for this and a B3 to find out the hard way. I've narrowed down my search to one of these http://www.ayagroup.com/product.php?productid=18203 I'm just waiting for some confirmation from the manufacterer on my setup. Ya, it's only USB, but my data will already be on my 4 HDDs, and this should provide enough speed to stream HD content from my media player. Since I already have 2 NAS boxes, I don't think I need a third one like the B3, but just need more networked storage space.

kurt2000
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Re: Do the e-SATA ports support Port Multiplier?

Post by kurt2000 » 19 Dec 2010, 14:30

Hi

i know from the open-rd platform (same cpu as b3) that you can use sata port multiplier, i saw it on there mailing list.

wkr.

kurt2000
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Re: Do the e-SATA ports support Port Multiplier?

Post by kurt2000 » 19 Dec 2010, 14:42

kurt2000 wrote:Hi

i know from the open-rd platform (same cpu as b3) that you can use sata port multiplier, i saw it on there mailing list.

wkr.
http://plugcomputer.org/plugforum/index ... pic=1783.0
http://plugcomputer.org/plugforum/index ... pic=1075.0


Wkr.

albert
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Re: Do the e-SATA ports support Port Multiplier?

Post by albert » 30 Dec 2010, 03:57

I want to bump this thread up, as it is too interesting to let it die.

Johannes/Tor, any updates on this?

Wouldn't it be an idea for excito to create a bubba storage with 2 or 4 disks and a FIS based port multiplier build in? That way it can be used on the B3 as extra storage (beit RAID 0, 1, or 5 (in case of 3/4 disks).

To think of it, two 2 1/2 inch disks would fit nicely in a B3 housing.

Albert

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