Joining SATA RAID controllers?

  • Thread starter Thread starter Shawn Wilson
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Shawn Wilson

Assuming that I have two identical SATA RAID controllers, is it possible to
split a mirror set between the two controllers?

The reason I ask is because I am trying to set up a machine with 6 drives
(expandable to 8) and the 4 port controllers are much more affordable than
the 8 port ones. If I could set up say a stripe set on one controller of 3
of the drives, and mirror that set to 3 drives stripped on the other
controller, that would effectively be a 0+1 set across two controllers.

Is this just way out there, or is it feasible.

In the absence of such a solution, I'd just do a copy on a schedule or have
some backup software sync the separate sets. It would be nice to have it
happen at the hardware level though.

Thanks in advance!
 
In comp.sys.ibm.pc.hardware.storage Shawn Wilson said:
Assuming that I have two identical SATA RAID controllers, is it possible to
split a mirror set between the two controllers?
Click to expand...
The reason I ask is because I am trying to set up a machine with 6 drives
(expandable to 8) and the 4 port controllers are much more affordable than
the 8 port ones. If I could set up say a stripe set on one controller of 3
of the drives, and mirror that set to 3 drives stripped on the other
controller, that would effectively be a 0+1 set across two controllers.
Click to expand...
Is this just way out there, or is it feasible.
Click to expand...

It might be feasible, but it could create immense bus-load and it would
be difficult, since two bus masters would need to communicate with each
other at high speed and with a lot of data-flow reversals. I assume that
most reasonable controllers (side-note: Adaptec SATA is trash) will not
do this.

There are (or were) some exotic solutions out there that could do what
you want but with the controllers and sisk being in two different
computers and with a dedicated fast datalink between the two cards.
In the absence of such a solution, I'd just do a copy on a schedule or have
some backup software sync the separate sets. It would be nice to have it
happen at the hardware level though.
Click to expand...

Depending on the OS you use, why not do the RAID 1 layer in software
on top of two independent arrays? Or why not do the whole thing in
software? I have an array with two promise sata 150tx4 and software
RAID 5 under Linux.

Arno
 
Assuming that I have two identical SATA RAID controllers, is it possible
to
split a mirror set between the two controllers?

The reason I ask is because I am trying to set up a machine with 6 drives
(expandable to 8) and the 4 port controllers are much more affordable than
the 8 port ones. If I could set up say a stripe set on one controller of 3
of the drives, and mirror that set to 3 drives stripped on the other
controller, that would effectively be a 0+1 set across two controllers.

Is this just way out there, or is it feasible.

In the absence of such a solution, I'd just do a copy on a schedule or have
some backup software sync the separate sets. It would be nice to have it
happen at the hardware level though.
Click to expand...

Like ARIO-FST?
www.ariodata.com/products/pdfs/fst.pdf
 
Arno Wagner said:
Depending on the OS you use, why not do the RAID 1 layer in software
on top of two independent arrays? Or why not do the whole thing in
software? I have an array with two promise sata 150tx4 and software
RAID 5 under Linux.

Arno
Click to expand...

That makes a lot of sense... I'll just set up the two controllers
identically but seperate, then use software RAID to mirror one to the other.

I like the idea of hardware RAID in general, but for this part of it,
software RAID solves the problem.

Thanks.
 
Arno Wagner said:
It might be feasible, but it could create immense bus-load and it would
be difficult, since two bus masters would need to communicate with each
other at high speed and with a lot of data-flow reversals.
Click to expand...

What a load of nonsense.
That is no more different than software mirroring
I assume that most reasonable controllers (side-note: Adaptec SATA is
trash) will not do this.
Click to expand...

The 'reasonal' ones might, the cheaper ones may not.
It is not uncommon for Host Adapter built-in Setup utilities to control
more than one Host Adapter. The ones that do may just behave like it was
a single 4 (or more) channel controller.
 
yes u can do that with linux and soft based raid. Onily u have to see if u
can mix hw raid inside each controller and then sowtware raid among
controllers.
 
These PCI 4-ports are software RAID, same as Windows built-in.

Just do the RAID 1 on the controller and RAID 0 in Windows.
 
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