question about consecutive data group transfers

Mcgrath, Jim Jim_Mcgrath at maxtor.com
Tue Sep 4 14:00:46 PDT 2001


* From the T10 Reflector (t10 at t10.org), posted by:
* "Mcgrath, Jim" <Jim_Mcgrath at maxtor.com>
*

If memory serves me correctly, the target is NOT REQUIRED to, but is
PERMITTED to.  That is, the target can keep data flowing smoothly between
data groups, but always has the option of not doing so.  However, I believe
there is a limit based on data group size (i.e. if the initiator is still
ACKing for group 1 the target can send out REQs for group 2, but not the
following group 3 - that was initially required to make implementations
easier, but I don't remember if it got into the final wording).  Normally
you would never see this issue since data groups are large (i.e. 512 bytes
or so, or > 3 us at 160 MB/s speeds), but you may see it.  Once again, even
if not prohibited, the target could always decline to send out REQs for
group 3 as a target implementation issue.

Specially, the initiator cannot could on this happening at the end of every
data group simply because the target may want to disconnect at the end of
that data group.

Jim




-----Original Message-----
From: Armen Avakian [mailto:aavakian at emc.com]
Sent: Tuesday, September 04, 2001 1:31 PM
To: t10 at t10.org
Subject: question about consecutive data group transfers


* From the T10 Reflector (t10 at t10.org), posted by:
* Armen Avakian <aavakian at emc.com>
*

Hi,

In 160/m, when the target is tranmitting or receiving consecutive data
groups (DT_REQ = 1, IU_REQ = 0),
will the target issue REQ's up to the negotiated sync offset for the current

data group, even though the initiator has not ACKed all the REQ's prior to
CRC
REQ for the previous data group? Or will it only issue REQ's up to the
difference
between negotiated offset and outstanding ACK's from previous data group?

Thanks in advance,

aa
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org
*
* For T10 Reflector information, send a message with
* 'info t10' (no quotes) in the message body to majordomo at t10.org




More information about the T10 mailing list