End-to-end logical block guard checking question

George Penokie gop at us.ibm.com
Fri Jan 23 06:54:41 PST 2004


* From the T10 Reflector (t10 at t10.org), posted by:
* George Penokie <gop at us.ibm.com>
*
This is a multipart message in MIME format.
--=_alternative 0051D44086256E24_=
Content-Type: text/plain; charset="US-ASCII"


In the protection information description in SBC-2 section 4.5.1
Protection information overview the following statement is made: 

If the logical unit is formatted with protection information and the
EMDP bit is set to one in the Disconnect-Reconnect mode page (see
SPC-3), then checking of the logical block reference tag or the logical
block guard within the service delivery subsystem may cause false errors
because logical blocks may be transmitted out of order. 

The statement that false errors may occur because blocks may be
transmitted out of order does not apply to the logical block guard as
that is a check of the block itself and does not care what the order of
the blocks is. Although it may be possible that a service delivery
subsystem may see data within a block the is not in the original order
that is not how the above statement reads. 

The question is does it make sense to make a statement about the logical
block guard causing false error? Is yes then the reason has to change
because as currently stated it is illogical.   

Bye for now,
George Penokie

Dept 2C6  114-2 N212
E-Mail:    gop at us.ibm.com
Internal:  553-5208
External: 507-253-5208   FAX: 507-253-2880



--=_alternative 0051D44086256E24_=
Content-Type: text/html; charset="US-ASCII"


<br><font size=2 face="sans-serif">In the protection information description
in SBC-2 section 4.5.1 Protection information overview the following statement
is made:</font>
<br>
<br><font size=2 face="sans-serif">If the logical unit is formatted with
protection information and the EMDP bit is set to one in the Disconnect-Reconnect
mode page (see SPC-3), then checking of the logical block reference tag
or the logical block guard within the service delivery subsystem may cause
false errors because logical blocks may be transmitted out of order.</font>
<br>
<br><font size=2 face="sans-serif">The statement that false errors may
occur because blocks may be transmitted out of order does not apply to
the logical block guard as that is a check of the block itself and does
not care what the order of the blocks is. Although it may be possible that
a service delivery subsystem may see data within a block the is not in
the original order that is not how the above statement reads. </font>
<br>
<br><font size=2 face="sans-serif">The question is does it make sense to
make a statement about the logical block guard causing false error? Is
yes then the reason has to change because as currently stated it is illogical.
&nbsp;</font>
<br><font size=2 face="sans-serif"><br>
Bye for now,<br>
George Penokie<br>
<br>
Dept 2C6 &nbsp;114-2 N212<br>
E-Mail: &nbsp; &nbsp;gop at us.ibm.com<br>
Internal: &nbsp;553-5208<br>
External: 507-253-5208 &nbsp; FAX: 507-253-2880<br>
<br>
</font>
--=_alternative 0051D44086256E24_=--




More information about the T10 mailing list