zfs discuss - Apr 2008 - ZFS volume export to USB-2 or Firewire?

Currently it is easy to share a ZFS volume as an iSCSI target.  Has 
there been any thought toward adding the ability to share a ZFS volume 
via USB-2 or Firewire to a directly attached client?

There is a substantial market for storage products which act like a 
USB-2 or Firewire "drive".  Some of these offer some form of RAID. 
It seems to me that ZFS with a server capability to appear as several 
USB-2 or Firewire drives (or eSATA) may be appealing for larger RAIDs 
of several terrabytes.

Is anyone aware of an application which can usefully share a ZFS 
volume (essentially a file) in this way?

Bob
=====================================Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

I''m not sure how this is a ZFS function?  You''re talking about
using ZFS to create a USB drive?  So you''d want a small box running ZFS
with a USB interface that you can just plug into other computers to access the
storage?

Well the first problem is that USB cables are directional, and you
don''t have the port you need on any standard motherboard.  That means
you''ll need a custom interface board of some kind to give you access to
the right kind of USB plug, and then you''d need custom drivers to run
that.

So you need custom hardware followed by a custom USB driver.  However once
you''ve done that you just read ZFS the same way you would read any
filesystem.

Adding iSCSI support to ZFS is relatively easy since Solaris already supported
TCP/IP and iSCSI.  Adding USB support is much more difficult and isn''t
likely to happen since afaik the hardware to do it just doens''t exist.
 
 
This message posted from opensolaris.org

Ross wrote:
> I''m not sure how this is a ZFS function?  You''re talking
about using ZFS to create a USB drive?  So you''d want a small box
running ZFS with a USB interface that you can just plug into other computers to
access the storage?
> 
> Well the first problem is that USB cables are directional, and you
don''t have the port you need on any standard motherboard.  That means
you''ll need a custom interface board of some kind to give you access to
the right kind of USB plug, and then you''d need custom drivers to run
that.
> 
> So you need custom hardware followed by a custom USB driver.  However once
you''ve done that you just read ZFS the same way you would read any
filesystem.
> 
> Adding iSCSI support to ZFS is relatively easy since Solaris already
supported TCP/IP and iSCSI.  Adding USB support is much more difficult and
isn''t likely to happen since afaik the hardware to do it just
doens''t exist.
What do you mean by adding iSCSI support to ZFS ?

Solaris already has iSCSI, ZFS already knows how to share ZVOLs as iSCSI 
targets, ZFS pools can be created on an iSCSI target.  What more is 
needed for iSCSI and ZFS integration ?

-- 
Darren J Moffat

On Wed, 9 Apr 2008, Ross wrote:
>
> Well the first problem is that USB cables are directional, and you 
> don''t have the port you need on any standard motherboard.  That
Thanks for that info.  I did not know that.
> Adding iSCSI support to ZFS is relatively easy since Solaris already 
> supported TCP/IP and iSCSI.  Adding USB support is much more 
> difficult and isn''t likely to happen since afaik the hardware to
do
> it just doens''t exist.
I don''t believe that Firewire is directional but presumably the 
Firewire support in Solaris only expects to support certain types of 
devices.  My workstation has Firewire but most systems won''t have it.

It seemed really cool to be able to put your laptop next to your 
Solaris workstation and just plug it in via USB or Firewire so it can 
be used as a "removable" storage device.  Or Solaris could be used on 
appropriate hardware to create a more reliable portable storage 
device.  Apparently this is not to be and it will be necessary to deal 
with iSCSI instead.

I have never used iSCSI so I don''t know how difficult it is to use as 
temporary "removable" storage under Windows or OS-X.

Bob
=====================================Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

On Apr 9, 2008, at 11:46 AM, Bob Friesenhahn wrote:
> On Wed, 9 Apr 2008, Ross wrote:
>>
>> Well the first problem is that USB cables are directional, and you
>> don''t have the port you need on any standard motherboard. 
That
>
> Thanks for that info.  I did not know that.
>
>> Adding iSCSI support to ZFS is relatively easy since Solaris already
>> supported TCP/IP and iSCSI.  Adding USB support is much more
>> difficult and isn''t likely to happen since afaik the hardware
to do
>> it just doens''t exist.
>
> I don''t believe that Firewire is directional but presumably the
> Firewire support in Solaris only expects to support certain types of
> devices.  My workstation has Firewire but most systems won''t have
it.
>
> It seemed really cool to be able to put your laptop next to your
> Solaris workstation and just plug it in via USB or Firewire so it can
> be used as a "removable" storage device.  Or Solaris could be
used on
> appropriate hardware to create a more reliable portable storage
> device.  Apparently this is not to be and it will be necessary to deal
> with iSCSI instead.
>
> I have never used iSCSI so I don''t know how difficult it is to use
as
> temporary "removable" storage under Windows or OS-X.
i''m not so sure what you''re really after, but i''m
guessing one of two
things:

1) a global filesystem?  if so - ZFS will never be globally accessible  
from 2 hosts at the same time without an interposer layer such as NFS  
or Lustre .. zvols could be exported to multiple hosts via iSCSI or FC- 
target but that''s only 1/2 the story ..
2) an easy way to export volumes?  agree - there should be some sort  
of semantics that would a signal filesystem is removable and trap on  
USB events when the media is unplugged .. of course you''ll have  
problems with uncommitted transactions that would have to roll back on  
the next plug, or somehow be query-able

iSCSI will get you a block/character device level sharing from a zvol  
(pseudo device) or the equivalent of a blob filestore .. you''d have to
format it with a filesystem, but that filesystem could be a global one  
(eg: QFS) and you could multi-host natively that way.

---
.je

Bob Friesenhahn wrote:
> On Wed, 9 Apr 2008, Ross wrote:
>   
>> Well the first problem is that USB cables are directional, and you 
>> don''t have the port you need on any standard motherboard. 
That
>>     
>
> Thanks for that info.  I did not know that.
>
>   
>> Adding iSCSI support to ZFS is relatively easy since Solaris already 
>> supported TCP/IP and iSCSI.  Adding USB support is much more 
>> difficult and isn''t likely to happen since afaik the hardware
to do
>> it just doens''t exist.
>>     
>
> I don''t believe that Firewire is directional but presumably the 
> Firewire support in Solaris only expects to support certain types of 
> devices.  My workstation has Firewire but most systems won''t have
it.
>
> It seemed really cool to be able to put your laptop next to your 
> Solaris workstation and just plug it in via USB or Firewire so it can 
> be used as a "removable" storage device.  Or Solaris could be
used on
> appropriate hardware to create a more reliable portable storage 
> device.  Apparently this is not to be and it will be necessary to deal 
> with iSCSI instead.
>   
I just get my laptop within WiFi range and mount :-).  I don''t see any
benefit to a wire which is slower than Ethernet, when an Ethernet
port is readily available on almost all modern laptops.
 -- richard

On Wed, 9 Apr 2008, Richard Elling wrote:
> I just get my laptop within WiFi range and mount :-).  I don''t see
any
> benefit to a wire which is slower than Ethernet, when an Ethernet
> port is readily available on almost all modern laptops.
Under Windows or Mac, is this as convenient as pugging in a USB or 
Firewire disk or does it require system administrator type knowledge?

If you go to Starbucks, does your laptop attempt to mount your iSCSI 
volume on a (presumably) unreachable network?

Bob
=====================================Bob Friesenhahn
bfriesen at simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

On Wed, Apr 9, 2008 at 11:19 AM, Richard Elling <Richard.Elling at
sun.com> wrote:
>  I just get my laptop within WiFi range and mount :-).  I don''t
see any
>  benefit to a wire which is slower than Ethernet, when an Ethernet
>  port is readily available on almost all modern laptops.
I think what Bob meant was something like Apple''s Firewire target mode.

If you turn on the machine while holding down the "T" key, the machine
presents itself as a firewire drive. You can plug it in and access the
disk without booting. Since the host is not booted into an OS, there
is still only one machine accessing the filesystem.

In theory, you could do this today with a ZFS filesystem on a Mac,
since the target mode ability is in the machine''s firmware. To do it
with another brand of machine, you''d need a boot image that presented
the drive(s) as a firewire target. There may be micro linux images
that fit on a USB key and allow this.

-B

-- 
Brandon High bhigh at freaks.com
"The good is the enemy of the best." - Nietzsche