Electricity: measuring and testing – Conductor identification or location
Reexamination Certificate
2002-09-26
2004-10-26
Deb, Anjan K. (Department: 2858)
Electricity: measuring and testing
Conductor identification or location
C324S538000, C709S224000
Reexamination Certificate
active
06809505
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to storage systems. More particularly, the invention relates to a system and method of detecting an improper cable connection in a storage system.
BACKGROUND
A typical storage system includes one or more racks of storage devices or enclosures. A loop is a common topology in which the enclosures of a storage system are connected. Communication signals traverse the loop in one direction and pass from enclosure to enclosure in a daisy-chain fashion. Enclosures receiving communication signals targeted for another enclosure forward those signals along the loop.
An example of a prior art storage system
100
is shown in FIG.
1
. This storage system
100
has a plurality of enclosures
104
,
104
′,
104
″ and
104
″′ generally, enclosure
104
). Each enclosure
104
has a plurality of disk modules (not shown), and redundant link control cards (LCC)
108
,
108
′ (generally, LCC
108
), and redundant power supplies
112
,
112
′ (generally, power supply
112
). Partitioned into an “A” side and a “B” side, each enclosure
104
has redundant backend loops. One loop includes the “A” side of each enclosure
104
and the host processor
128
and the other loop includes the “B” side of the each enclosure
104
and the host processor
128
′.
Each LCC
108
includes a primary communications port
116
and an expansion communications port
120
. For clarity sake, reference numerals appear in
FIG. 1
for the primary communications ports
116
and expansion communications ports
120
of the enclosure
104
′″ only. The communications ports
116
,
120
are located at the side edges of the enclosure
104
, with the expansion communications port
120
being positioned above the primary communications port
116
.
Cables
124
connect the expansion communications port
120
of one enclosure
104
to the primary communications port
116
of the next enclosure
104
in the daisy-chain. Also, host processors
128
,
128
′ (generally, host processor
128
), which access the storage system
100
for data storage and retrieval, are each connected to the primary communications port
116
of one of the LCCs
108
of the enclosure
104
′″. The host processors
128
are thus part of the redundant daisy-chained loops.
The location of the communications ports
116
,
120
at the edges of the enclosures simplifies the cable connections between the enclosures
104
. Typically the expansion communications port
120
of one enclosure is directly below and near the primary communications port
116
of the neighboring enclosure. Consequently, only two relatively short cables
124
pass between two neighboring enclosures
104
, one cable
124
at each enclosure edge. Thus the cabling between enclosures
104
is relatively straightforward and improper cable connections between enclosures
104
easy to detect.
Storage systems, however, are becoming increasingly sophisticated and the cabling between enclosures increasingly complicated. Some storage systems employ more than one backend loop, thus increasing the number of cables that connect to each LCC and causing some cables to cross over other cables. A backend loop is the loop formed when the host processor is connected to the storage system
100
.
FIG. 1
has one backend loop on each host processor
128
. The layout of LCCs and power supplies in an enclosure may vary from that shown in
FIG. 1
, requiring cables to be longer and to extend into the interior of the storage system rather than remain along the its edges. The final product can appear like a tangled nest of cables, and the possibility that the storage system has an improper cable connection becomes more likely. Moreover, the tangle of cables can complicate and frustrate attempts to troubleshoot a storage system with an improper cable connection. Visually inspecting the storage system to see if the cabling is done properly becomes more difficult and less trustworthy. Therefore, there is a need for a system and method for testing the connectivity of cables to detect a system with an improper cable connection.
SUMMARY
In one aspect, the invention features a system comprising an enclosure having boards. Each board has a communications port that receives a message identifying a redundant backend network to which that board is connected. The enclosure determines whether the system has an improper cable connection by determining from the messages whether the boards are connected to the same redundant backend network.
In another aspect, the invention features an enclosure for a system comprising a first and a second card. Each card has a communications port. A first cable conveys an identifier to the communications port of the first card, and a second cable conveys an identifier to the communications port of second card. Each identifier identifies a network to which the card receiving that identifier is connected. The enclosure also includes means for determining if the cards are connected to different networks based on the identifiers conveyed to the communications ports of the first and second cards.
In yet another aspect, the invention features a method of testing connectivity of cabling in a storage system that implements redundancy. A first identifier is received over a first cable at a first card in an enclosure. A second identifier is received over a second cable at a second card in the enclosure. The method also includes determining if the cards are connected to different networks based on the first and second identifiers.
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patent: 5522046 (1996-05-01), McMillen et al.
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patent: 5841997 (1998-11-01), Bleiweiss et al.
patent: 5890214 (1999-03-01), Espy et al.
patent: 5901151 (1999-05-01), Bleiweiss et al.
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patent: 6425049 (2002-07-01), Yamamoto et al.
patent: 2002/0044562 (2002-04-01), Killer, Jr. et al.
patent: 2002/0046276 (2002-04-01), Coffey et al.
Bailey Brian K.
Peeke Douglas E.
Reid Geoffrey
Tuttle James M.
Deb Anjan K.
EMC Corporation
Guerin & Rodriguez LLP
Rodriquez Michael A.
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