Seeking clarification on Threshold Out/In diagnostic pages
Raj.Divecha at dothill.com
Fri May 4 13:36:42 PDT 2012
Formatted message: <a href="http://www.t10.org/cgi-bin/ac.pl?t=r&f=r1205042_f.htm">HTML-formatted message</a>
Yeah that's a strong indicator indeed, I too acknowledge that in my email.
However, those placeholder/reserved threshold elements are a huge wastage and
amounts to unnecessary data being transferred. Thus I believe that the
authors of the SES spec wouldn't have intended the same and is a thing that
does not clearly come out of the spec.
Consider the below given configuration of an imaginary enclosure. In this we
are talking about sending/receiving 352 bytes of useless data, that is
approximately 80% wastage. The number of useless bytes would almost multiply
as you add subenclosures.
Array Device Slot elements
Power Supply elements
Temperature Sensor elements
Door Lock element
Audible Alarm element
Enclosure Services Controller Electronics elements
Invalid Operation Reason element
Voltage Sensor elements
Current Sensor elements
SAS Expander elements
SAS Connector elements
VS element 1
VS element 2
As the authors limited the number of element types appearing in the
Additional Element Status diagnostic page, it is probable that they intended
the same for the Threshold Out/In diagnostic page but unfortunately it didn't
came out that way in the spec.
From: Matthew_Jacobs at Dell.com [mailto:Matthew_Jacobs at Dell.com]
Sent: Friday, May 04, 2012 1:42 PM
To: Raj Divecha; t10 at t10.org
Subject: RE: Seeking clarification on Threshold Out/In diagnostic pages
The descriptions of the threshold control descriptor list and the threshold
status descriptor list in sections 6.1.8 and 6.1.9 state that the list
contains a control/status "descriptor for each type descriptor header in the
Configuration diagnostic page". From that, I believe all individual elements
defined in the Configuration diagnostic page have a threshold element in the
Threshold in/Out diagnostic page even if it is just a placeholder/reserved
From: owner-t10 at t10.org<mailto:owner-t10 at t10.org>
[mailto:owner-t10 at t10.org]<mailto:[mailto:owner-t10 at t10.org]> On Behalf Of
Sent: Friday, May 04, 2012 12:29 PM
To: t10 at t10.org<mailto:t10 at t10.org>
Subject: SES: Seeking clarification on Threshold Out/In diagnostic pages
I searched the T10 emails for this but didn't found anything.
The SES spec is a bit ambiguous regarding which element types should be
included in the Threshold Out/In diagnostic page. A clarification would be
The following are the excerpts from the 2r20 spec. Below each excerpt is my
comment. The questions are at the end of the email.
6.1.8 Threshold Out diagnostic page
The Threshold Out diagnostic page is transmitted to the enclosure services
process to establish threshold values for those elements that have limited
sensing capability (e.g., temperature sensors, uninterruptible power
supplies, voltage sensors, and current sensors).
My comment: this statement "possibly" suggests that this page includes only
those element types that support threshold.
The threshold control descriptor list contains a threshold control descriptor
for each type descriptor header in the Configuration diagnostic page (see
My comment: this statement "strongly" suggests that this page includes all
element types, whether or not they support thresholds.
7.1 Element definitions overview, Table 60
My comment: shows which element type support thresholds and which not.
7.2.4 Threshold control element format
All fields in the threshold control element are advisory. The enclosure
services process shall ignore the contents of the threshold control element
for those elements that have no value to be compared with a threshold and for
those elements that do not implement the threshold function.
My comment: this statement suggests that threshold descriptors for even those
element types, that do not support threshold, are included in the Threshold
Out/In diagnostic page, however, the application client and the enclosure
services process (ESP) are supposed to ignore them.
7.3 Field definitions for all element types
My comments: this section does not describe the threshold descriptors for
element types that do not support threshold. Not even a generic descriptor
with 4 reserved bytes is defined.
If the readers are to assume that the threshold descriptors for even those
element types that do not support threshold are to be included in the
Threshold Out/In diagnostic pages, then they are also supposed to assume a
generic 4-byte threshold descriptors with all bytes as reserved as they are
supposed to be ignored by both the application client and the ESP.
If the readers are to assume that the Threshold Out/In pages should include
only those element types that support threshold then there is no question of
assuming a generic 4-bytes reserved descriptor and no question of ignoring
Based on the above there are many "strong" points that indicate that the
Threshold Out/In pages include even those element types that do not support
thresholds and there are some "weak" points that indicate that they don't
include those element types.
Did the spec authors intended to include additional descriptors in the page
that will never be used?
Or were the Threshold Out/In diagnostic pages meant to be similar to the
Additional Element Status diagnostic page where in only a selected subset of
element types appear in these pages?
In my opinion the spec authors did not intend to include additional
descriptors in the page that will never be used and thus the Threshold Out/In
diagnostic page is similar to the Additional Element Status diagnostic page
where only a limited subset of element types appear in these pages. However,
I could be wrong, thus please clarify.
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