Fwd: SAM-5: copy manager seldom an application client

Ralph Weber roweber at ieee.org
Thu Jul 31 12:36:00 PDT 2014


* From the T10 Reflector (t10 at t10.org), posted by:
* Ralph Weber <roweber at ieee.org>
*
I oppose the requested change.
A copy manager that cannot act as an application client cannot send
READ commands to source devices and WRITE commands to destination
devices. This would be profoundly debilitating to a standalone copy
manager such as the one cited as the justification for its own evisceration.
All the best,
.Ralph
On 7/31/2014 1:49 PM, John Lohmeyer wrote:
> * From the T10 Reflector (t10 at t10.org), posted by:
> * John Lohmeyer <lohmeyer at t10.org>
> *
> All,
>
> Douglas Gilbert <dgilbert at interlog.com> has requested that I forward his
below message to the T10 Reflector. Please cc him on any response as he is
not subscribed to the reflector.
>
> John
>
>> -------- Forwarded Message --------
>> Subject: SAM-5: copy manager seldom an application client
>> Date: Wed, 30 Jul 2014 18:44:57 -0400
>> From: Douglas Gilbert <dgilbert at interlog.com>
>> Reply-To: dgilbert at interlog.com
>> To: T10 Reflector (t10 at t10.org) <t10 at t10.org>
>>
>> In the SCSI Classes overview (clause 4.6.1 on page 32 in
>> sam5r17.pdf) the UML diagram shows multiple inheritance
>> for the copy manager. It is saying that a copy manager
>> is (a type of) device server and is (a type of) application
>> client. The first half of that statement is true but
>> the second is only true for some standalone copy managers
>> (see spc4r37a.pdf clause 5.16.2, figure 17).
>>
>> IMO the inheritance arrow (blue) from the copy_manager
>> to the application_client should be dropped. Other options
>> are to introduce a standalone_copy_manager which the
>> copy_manager contains 0 or 1 of. Another level of indirection
>> is needed to identify those standalone_copy_managers that use
>> T10 techniques to talk to the device servers owning the source
>> and destination of the copy (as the standalone_copy_manager
>> can use other techniques such as a network). Then the UML
>> diagram can say the t10_standalone_copy_manager is (a type
>> of) application_client.
>>
>> Doug Gilbert
>>
>>
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