SLIDE 31 31 SquidTON: Reliable & Fault Tolerant Overlay
- Pervasive Grid systems are dynamic, with nodes joining, leaving and
failing relatively often
- => data loss and temporarily inconsistent overlay structure
- => the system cannot offer guarantees
B ild d d i t th l t k – Build redundancy into the overlay network – Replicate the data
- SquidTON = Squid Two-tier Overlay Network
– Consecutive nodes form unstructured groups, and at the same time are connected by a global structured overlay (e.g. Chord) – Data is replicated in the group
25 22 249 17 10 22 17 10 33 82 86 91 94 128 132 150 157 141 231 249 240 185 192 Groups of nodes Group identifier 250 231 249 240 185 192 128 132 150 157 141 161 82 86 91 94 33 25 22 102 41
Content Descriptors and Information Space
- Data element = a piece of information that is indexed and discovered
– Data, documents, resources, services, metadata, messages, events, etc.
- Each data element has a set of keywords associated with it, which
y describe its content => data elements form a keyword space
2D keyword space for a P2P file sharing system
network Document
keyword2
computer
keyword1
comp* Complex query (comp*, *)
keyword1 keyword2
2D keyword space for a P2P file sharing system
network Document
keyword2
computer
keyword1
comp* Complex query (comp*, *)
keyword1 keyword2
network Document
keyword2
computer
keyword1
network Document
keyword2
computer
keyword1
computer
keyword1
comp* Complex query (comp*, *)
keyword1 keyword2
comp* Complex query (comp*, *)
keyword1 keyword2
comp* Complex query (comp*, *)
keyword1 keyword2
3D keyword space for resource sharing, using the attributes: storage space, base bandwidth and cost
Storage space (MB) Base bandwidth (Mbps)
Computational resource
Cost
30 100 9
Storage space (MB) Base bandwidth (Mbps) C
t
20 25 10 Complex query (10, 20-25, *)
3D keyword space for resource sharing, using the attributes: storage space, base bandwidth and cost
Storage space (MB) Base bandwidth (Mbps)
Computational resource
Cost
30 100 9
Storage space (MB) Base bandwidth (Mbps) C
t
20 25 10 Complex query (10, 20-25, *)
Storage space (MB) Base bandwidth (Mbps)
Computational resource
Cost
30 100 9
Storage space (MB) Base bandwidth (Mbps)
Computational resource
Cost
30 100 9
Storage space (MB) Base bandwidth (Mbps)
Computational resource
Cost
30 100 9
Storage space (MB) Base bandwidth (Mbps) C
t
20 25 10 Complex query (10, 20-25, *)
Storage space (MB) Base bandwidth (Mbps) C
t
20 25 10 Complex query (10, 20-25, *)
Storage space (MB) Base bandwidth (Mbps) C
t
20 25 10 Complex query (10, 20-25, *)