Performance with two drives on the same SATA controller.

  • Thread starter Thread starter fj
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fj

Is it correct that a SATA controller has the same limitation as a PATA
controller with two drives? I.e., the controller can only handle data flow
to one drive at a time?
So, for example, creating a RAID 0 array on two SATA drives on the same
controller will impact the performance of the array? [vs creating the array
with two drives on different controllers].

Thanks
 
fj said:
Is it correct that a SATA controller has the same limitation as a PATA controller with
two drives? I.e., the controller can only handle data flow to one drive at a time?
Click to expand...

Nope, that is due to the number of drives per cable,
and there is only one drive per SATA cable.
So, for example, creating a RAID 0 array on two SATA drives on the same controller will
impact the performance of the array? [vs creating the array with two drives on
different controllers].
Click to expand...

Nope. In fact you cant necessarily create a RAID0 array
across two different controllers unless you do that by software.
 
fj said:
Is it correct
Click to expand...

So where does it say that?
that a SATA controller has the same limitation as a PATA controller
Click to expand...

No, not in theory at least.
In practice however your SATA controller may just be a PATA controller
with pata->sata converters.
with two drives?
Click to expand...

On the same channel, you mean.
I.e., the controller can only handle data flow to one drive at a time?
Nope.

So, for example, creating a RAID 0 array on two SATA drives
on the same controller will impact the performance of the array?
Click to expand...

Nope.
And even if it is a PATA->SATA type controller you may put them
on different channels, just like you do on a true PATA controller.
[vs creating the array with two drives on different controllers].
Click to expand...

They still share the PCI bus.
 
Previously fj said:
Is it correct that a SATA controller has the same limitation as a PATA
controller with two drives? I.e., the controller can only handle data flow
to one drive at a time?
So, for example, creating a RAID 0 array on two SATA drives on the same
controller will impact the performance of the array? [vs creating the array
with two drives on different controllers].
Click to expand...

On the disk side this problem is not present anymore. In the controller
itself it depends on the design. And on the bus (computer) side, nothing
has changed. However bandwidths in the remaining bottlenecks are typically
much higher than on the IDE bus, so for practical purposes with two
disks, there should be no or almost no slowdown. If you put 8 or 16
disks on a controller, the remaining bottlenecks may become an issue.

Arno
 
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