Are large RAID stripe sizes useful with FreeBSD?

Ivan Voras ivoras at
Mon Mar 31 15:48:15 PDT 2008

On 01/04/2008, Scott Long <scottl at> wrote:

> TCQ is a protocol specific to parallel SCSI that involves the use of
>  protocol messages and control signals found only on a parallel SCSI bus.
>  PCI RAID controllers that present a SCSI interface to the OS don't use
>  real TCQ to communicate between the OS and the controller.  Even though
>  these kinds of controllers use the SCSI command protocol, they still use
>  a custom device-specific low-level communication protocol that handles
>  the transfer and queuing of commands.  External RAID
>  controllers/enclosures do use the appropriate SCSI/SAS/FC/SATA bus
>  queuing mechanism, but I'm not sure if that's what you're talking about
>  here.

Your're right, I'm not. On further thought it's logical - if RAID
controllers talked plain SCSI to the OS there wouldn't be a need for
specific drivers, right?

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