[log in to unmask] wrote:
>
(stuff snipped)

> The question boils down to:  is it possible for a DS-queue process to
> preempt a CS-queue process for disk I/O?  The extract in question is
> writing to a flat file on the same disk volume set, but it's opened the
> database for read-only access.
>
If the DS queue process is holding a resource (semaphore, dataset lock)
that a higher priority process wants and has to block for, the OS might
"boost" the DS queue process to a higher priority (temporarily) until
it releases the resource.

I assume this is what you are experiencing, I am not sure but a look at
the actual priority of the DS queue process (with Glance, SOS, etc.)
might show something like D152 for the priority, until the resource is
released.

Goetz.