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Old 02-13-2011, 05:53 PM
Rudi Ahlers
 
Default how do export a block device via eSATA?

Does any one know how to, if at all possible currently, to export a
block device via eSATA? i.e. how do I do something like iSCSI, but
over eSATA?

I have a cheat ($15 probably?) media player at home (Egreat EG-M31B
Network Media Tank - awesome little machine) that runs some flavor of
Debian and can be connected to any PC via eSATA as an external HDD's.
i.e. it exports the built-in HDD as a block device to the host (My
laptop or PC).

Now, the question is, how can I do this on Linux?
Would I need a different eSATA card than the on-board eSATA port on
most motherboards? Or would the on-board one work?

The question is, how do I tell Linux to export a file system, or block
device via the eSATA port?

If any one has attempted this before, then please share some knowledge
or pointers on the subject. I couldn't find anything using google, but
I may not necessarily have searched for the correct terms?

--
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 06:00 PM
John R Pierce
 
Default how do export a block device via eSATA?

On 02/13/11 10:53 AM, Rudi Ahlers wrote:
> Does any one know how to, if at all possible currently, to export a
> block device via eSATA? i.e. how do I do something like iSCSI, but
> over eSATA?
>
> I have a cheat ($15 probably?) media player at home (Egreat EG-M31B
> Network Media Tank - awesome little machine) that runs some flavor of
> Debian and can be connected to any PC via eSATA as an external HDD's.
> i.e. it exports the built-in HDD as a block device to the host (My
> laptop or PC).
>
> Now, the question is, how can I do this on Linux?
> Would I need a different eSATA card than the on-board eSATA port on
> most motherboards? Or would the on-board one work?

I suspect your media tank is doing something electrical, like idling its
processor, and re-routing the sata port directly to the internal storage
device, when its in this mode. I'm unaware of any SATA target drivers
(as opposed to the normal initiator drivers in libata etc)



_______________________________________________
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Old 02-13-2011, 06:44 PM
Robert Heller
 
Default how do export a block device via eSATA?

At Sun, 13 Feb 2011 11:00:39 -0800 CentOS mailing list <centos@centos.org> wrote:

>
> On 02/13/11 10:53 AM, Rudi Ahlers wrote:
> > Does any one know how to, if at all possible currently, to export a
> > block device via eSATA? i.e. how do I do something like iSCSI, but
> > over eSATA?
> >
> > I have a cheat ($15 probably?) media player at home (Egreat EG-M31B
> > Network Media Tank - awesome little machine) that runs some flavor of
> > Debian and can be connected to any PC via eSATA as an external HDD's.
> > i.e. it exports the built-in HDD as a block device to the host (My
> > laptop or PC).
> >
> > Now, the question is, how can I do this on Linux?
> > Would I need a different eSATA card than the on-board eSATA port on
> > most motherboards? Or would the on-board one work?
>
> I suspect your media tank is doing something electrical, like idling its
> processor, and re-routing the sata port directly to the internal storage
> device, when its in this mode. I'm unaware of any SATA target drivers
> (as opposed to the normal initiator drivers in libata etc)

More likely, it is running some custom software the connects to the
exposed port (which is probably not a typical PC SATA port -- it would
be wired like a Hard Drive's SATA connector (opposite gender, opposite
signal directions, etc.). The custom software presents itself on this
port like it was a hard drive and implements some sort of logical hard
drive based on the actual internal hard drive -- not really much
different from a USB connected mp3 player or camera -- the USB
connected mp3 players / camera are just using a different physical
interface (USB), but the logic is the same. Again, the USB port on
these devices is 'wired' the opposite from the USB port on a normal PC
and the logic behind it is also opposite (you cannot really connect a
USB port of one PC to the USB port of another -- there is no such thing
as a USB 'cross over' (Ethernet) or null-modem (RS232) cable in the USB
(or firewire) world). The processor in the little box is implementing
much that same sort of processing that goes on inside the micro
processor on the controller board of a hard drive -- modern hard drive
controller boards are really a full fledged little computer running a
very special program that implements the drive end of the mass storage
interface (SCSI, SATA, PATA, etc.). The media tank is just taking this
to a different level.

>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>

--
Robert Heller -- 978-544-6933 / heller@deepsoft.com
Deepwoods Software -- http://www.deepsoft.com/
() ascii ribbon campaign -- against html e-mail
/ www.asciiribbon.org -- against proprietary attachments



_______________________________________________
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CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 06:58 PM
Rudi Ahlers
 
Default how do export a block device via eSATA?

On Sun, Feb 13, 2011 at 9:44 PM, Robert Heller <heller@deepsoft.com> wrote:
> At Sun, 13 Feb 2011 11:00:39 -0800 CentOS mailing list <centos@centos.org> wrote:
>
>>
>> On 02/13/11 10:53 AM, Rudi Ahlers wrote:
>> > Does any one know how to, if at all possible currently, to export a
>> > block device via eSATA? i.e. how do I do something like iSCSI, but
>> > over eSATA?
>> >
>> > I have a cheat ($15 probably?) *media player at home (Egreat EG-M31B
>> > Network Media Tank - awesome little machine) that runs some flavor of
>> > Debian and can be connected to any PC via eSATA as an external HDD's.
>> > i.e. it exports the built-in HDD as a block device to the host (My
>> > laptop or PC).
>> >
>> > Now, the question is, how can I do this on Linux?
>> > Would I need a different eSATA card than the on-board eSATA port on
>> > most motherboards? Or would the on-board one work?
>>
>> I suspect your media tank is doing something electrical, like idling its
>> processor, and re-routing the sata port directly to the internal storage
>> device, when its in this mode. * I'm unaware of any SATA target drivers
>> (as opposed to the normal initiator drivers in libata etc)
>
> More likely, it is running some custom software the connects to the
> exposed port (which is probably not a typical PC SATA port -- it would
> be wired like a Hard Drive's SATA connector (opposite gender, opposite
> signal directions, etc.). *The custom software presents itself on this
> port like it was a hard drive and implements some sort of logical hard
> drive based on the actual internal hard drive -- not really much
> different from a USB connected mp3 player or camera -- the USB
> connected mp3 players / camera are just using a different physical
> interface (USB), but the logic is the same. Again, the USB port on
> these devices is 'wired' the opposite from the USB port on a normal PC
> and the logic behind it is also opposite (you cannot really connect a
> USB port of one PC to the USB port of another -- there is no such thing
> as a USB 'cross over' (Ethernet) or null-modem (RS232) cable in the USB
> (or firewire) world). The processor in the little box is implementing
> much that same sort of processing that goes on inside the micro
> processor on the controller board of a hard drive -- modern hard drive
> controller boards are really a full fledged little computer running a
> very special program that implements the drive end of the mass storage
> interface (SCSI, SATA, PATA, etc.). *The media tank is just taking this
> to a different level.
>
>>
>>
>>


Sure, I understand what you're saying, but the question is: If they
can do it with a cheap device like this, then surely one should be
able todo it with a normal / server motherboard? Obviously they won't
tell us their secrets, so I need to dig around to see how todo it
myself. This particular device has a eSATA slave + eSATA Master mode.
i.e. I can connect another device to this one and they both work
together, and then when I connect the first one to my PC, I have 2
HDD's - i.e. a cheap JBOD implementation.


I'm trying to see if I can setup a Linux JBOD on a server chassis
with say 16 HDD's or something, and then connect it to another server
via eSATA - i.e. building a cheap scalable SAN.



P.S. You actually do get USB cross-over cables:
http://en.kioskea.net/faq/342-connecting-two-computers-with-a-usb-cable
- they work quite well. They're not as fast a gigabit but works very
well for older PC's without LAN.


--
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 07:28 PM
Robert Heller
 
Default how do export a block device via eSATA?

At Sun, 13 Feb 2011 21:58:11 +0200 CentOS mailing list <centos@centos.org> wrote:

>
> On Sun, Feb 13, 2011 at 9:44 PM, Robert Heller <heller@deepsoft.com> wrote:
> > At Sun, 13 Feb 2011 11:00:39 -0800 CentOS mailing list <centos@centos.org> wrote:
> >
> >>
> >> On 02/13/11 10:53 AM, Rudi Ahlers wrote:
> >> > Does any one know how to, if at all possible currently, to export a
> >> > block device via eSATA? i.e. how do I do something like iSCSI, but
> >> > over eSATA?
> >> >
> >> > I have a cheat ($15 probably?) *media player at home (Egreat EG-M31B
> >> > Network Media Tank - awesome little machine) that runs some flavor of
> >> > Debian and can be connected to any PC via eSATA as an external HDD's.
> >> > i.e. it exports the built-in HDD as a block device to the host (My
> >> > laptop or PC).
> >> >
> >> > Now, the question is, how can I do this on Linux?
> >> > Would I need a different eSATA card than the on-board eSATA port on
> >> > most motherboards? Or would the on-board one work?
> >>
> >> I suspect your media tank is doing something electrical, like idling its
> >> processor, and re-routing the sata port directly to the internal storage
> >> device, when its in this mode. * I'm unaware of any SATA target drivers
> >> (as opposed to the normal initiator drivers in libata etc)
> >
> > More likely, it is running some custom software the connects to the
> > exposed port (which is probably not a typical PC SATA port -- it would
> > be wired like a Hard Drive's SATA connector (opposite gender, opposite
> > signal directions, etc.). *The custom software presents itself on this
> > port like it was a hard drive and implements some sort of logical hard
> > drive based on the actual internal hard drive -- not really much
> > different from a USB connected mp3 player or camera -- the USB
> > connected mp3 players / camera are just using a different physical
> > interface (USB), but the logic is the same. Again, the USB port on
> > these devices is 'wired' the opposite from the USB port on a normal PC
> > and the logic behind it is also opposite (you cannot really connect a
> > USB port of one PC to the USB port of another -- there is no such thing
> > as a USB 'cross over' (Ethernet) or null-modem (RS232) cable in the USB
> > (or firewire) world). The processor in the little box is implementing
> > much that same sort of processing that goes on inside the micro
> > processor on the controller board of a hard drive -- modern hard drive
> > controller boards are really a full fledged little computer running a
> > very special program that implements the drive end of the mass storage
> > interface (SCSI, SATA, PATA, etc.). *The media tank is just taking this
> > to a different level.
> >
> >>
> >>
> >>
>
>
> Sure, I understand what you're saying, but the question is: If they
> can do it with a cheap device like this, then surely one should be
> able todo it with a normal / server motherboard? Obviously they won't
> tell us their secrets, so I need to dig around to see how todo it
> myself. This particular device has a eSATA slave + eSATA Master mode.
> i.e. I can connect another device to this one and they both work
> together, and then when I connect the first one to my PC, I have 2
> HDD's - i.e. a cheap JBOD implementation.


You probably can't do it with 'a normal / server motherboard'. The SATA
/ eSATA ports on such a board are 'host' ports. You would need a 'disk'
port, which is *electrically* different -- it is no different than with
USB or Firewire devices. There is the 'host' side and there is the
'device' side. They are different.

>
>
> I'm trying to see if I can setup a Linux JBOD on a server chassis
> with say 16 HDD's or something, and then connect it to another server
> via eSATA - i.e. building a cheap scalable SAN.
>
>
>
> P.S. You actually do get USB cross-over cables:
> http://en.kioskea.net/faq/342-connecting-two-computers-with-a-usb-cable
> - they work quite well. They're not as fast a gigabit but works very
> well for older PC's without LAN.
>
>

--
Robert Heller -- 978-544-6933 / heller@deepsoft.com
Deepwoods Software -- http://www.deepsoft.com/
() ascii ribbon campaign -- against html e-mail
/ www.asciiribbon.org -- against proprietary attachments



_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 07:36 PM
John R Pierce
 
Default how do export a block device via eSATA?

On 02/13/11 12:28 PM, Robert Heller wrote:
> it is no different than with
> USB or Firewire devices. There is the 'host' side and there is the
> 'device' side. They are different.

actually, firewire is a peer to peer bus, like ethernet. there's no
'host' or 'device', there is just firewire.

</pendantic>


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Old 02-13-2011, 08:10 PM
Les Mikesell
 
Default how do export a block device via eSATA?

On 2/13/11 1:58 PM, Rudi Ahlers wrote:
>
> Sure, I understand what you're saying, but the question is: If they
> can do it with a cheap device like this, then surely one should be
> able todo it with a normal / server motherboard? Obviously they won't
> tell us their secrets, so I need to dig around to see how todo it
> myself. This particular device has a eSATA slave + eSATA Master mode.
> i.e. I can connect another device to this one and they both work
> together, and then when I connect the first one to my PC, I have 2
> HDD's - i.e. a cheap JBOD implementation.

If you are going to pass eSATA straight through, why would you want the other
motherboard involved at all instead of just using an external eSata enclosure?

> I'm trying to see if I can setup a Linux JBOD on a server chassis
> with say 16 HDD's or something, and then connect it to another server
> via eSATA - i.e. building a cheap scalable SAN.

It might make sense to RAID a bunch of disks locally, and export the combined
device as iscsi.

> P.S. You actually do get USB cross-over cables:
> http://en.kioskea.net/faq/342-connecting-two-computers-with-a-usb-cable
> - they work quite well. They're not as fast a gigabit but works very
> well for older PC's without LAN.

I thought those were really implemented as back-to-back ethernet converters.

--
Les Mikesell
lesmikesell@gmail.com
_______________________________________________
CentOS mailing list
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http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 08:21 PM
Rudi Ahlers
 
Default how do export a block device via eSATA?

On Sun, Feb 13, 2011 at 11:10 PM, Les Mikesell <lesmikesell@gmail.com> wrote:
> On 2/13/11 1:58 PM, Rudi Ahlers wrote:
>>
>> Sure, I understand what you're saying, but the question is: If they
>> can do it with a cheap device like this, then surely one should be
>> able todo it with a normal / server motherboard? Obviously they won't
>> tell us their secrets, so I need to dig around to see how todo it
>> myself. This particular device has a eSATA slave + eSATA Master mode.
>> i.e. I can connect another device to this one and they both work
>> together, and then when I connect the first one to my PC, I have 2
>> HDD's - i.e. a cheap JBOD implementation.
>
> If you are going to pass eSATA straight through, why would you want the other
> motherboard involved at all instead of just using an external eSata enclosure?

I'm trying to build a dense eSATA enclosure with say 16 or 24 drives


>
>> I'm trying to see if I can setup *a Linux JBOD on a server chassis
>> with say 16 HDD's or something, and then connect it to another server
>> via eSATA - i.e. building a cheap scalable SAN.
>
> It might make sense to RAID a bunch of disks locally, and export the combined
> device as iscsi.

The 1GBE LAN is a bit slow. SATA can push 6GBe, which is 6 times
faster than 1GBe. And, 6 ports on a LAN switch is a waste. Our 10GBe
switches are saturated (all ports filled) and very expensive.
So I'm looking at cheaper options, and thought eSATA could do the
trick quite well.

>
>> P.S. You actually do get USB cross-over cables:
>> http://en.kioskea.net/faq/342-connecting-two-computers-with-a-usb-cable
>> - they work quite well. They're not as fast a gigabit but works very
>> well for older PC's without LAN.
>
> I thought those were really implemented as back-to-back ethernet converters.

Yes, probably. But they work over USB so it's very handy.

>
> --
> * *Les Mikesell
> * * lesmikesell@gmail.com
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>



--
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 
Old 02-13-2011, 08:35 PM
John R Pierce
 
Default how do export a block device via eSATA?

On 02/13/11 1:21 PM, Rudi Ahlers wrote:
> I'm trying to build a dense eSATA enclosure with say 16 or 24 drives

thats a stunningly bad way to go about it.

A) if you want JBOD, use a SAS/SATA enclosure with a SAS host card, as
SATA doesn't support multichannel multiplexing.
or
B) if you want a SAN, use iSCSI or FCoE or something.
or
C) if you want a NAS, use NFS. this is the best solution for many
applications.











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Old 02-13-2011, 08:59 PM
Rudi Ahlers
 
Default how do export a block device via eSATA?

On Sun, Feb 13, 2011 at 11:35 PM, John R Pierce <pierce@hogranch.com> wrote:
> On 02/13/11 1:21 PM, Rudi Ahlers wrote:
>> I'm trying to build a dense eSATA enclosure with say 16 or 24 drives
>
> thats a stunningly bad way to go about it.
>
> A) if you want JBOD, use a SAS/SATA enclosure with a SAS host card, as
> SATA doesn't support multichannel multiplexing.


mmm, I didn't think of this


> or
> B) if you want a SAN, use iSCSI or FCoE or something.

As I said, I'm trying todo something cheaper. These are super
expensive in our country.


> or
> C) if you want a NAS, use NFS. * this is the best solution for many
> applications.

We already use iSCSI, which is a bit quicker than NFS



I'm merely exploring this "new" technology, seeing as so many vendor
incorporate it into cheap NAS devices (which are normally limited to 2
- 5 drives) to see if it could actually be used on a bigger scale.

>
>
>
>
>
>
>
>
>
>
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>



--
Kind Regards
Rudi Ahlers
SoftDux

Website: http://www.SoftDux.com
Technical Blog: http://Blog.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532
_______________________________________________
CentOS mailing list
CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

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