Two-dimensional RAID arrays maintain separate row and column parities for all their disks. Depend... more Two-dimensional RAID arrays maintain separate row and column parities for all their disks. Depending on their organization, they can tolerate between two and three concurrent disk failures without losing any data. We propose to enhance the robustness of these arrays by replacing a small fraction of these drives with storage class memory devices, and demonstrate how such a pairing is
Considerable expertr::lental eVidence has been accumulated showing that the performance ot progra... more Considerable expertr::lental eVidence has been accumulated showing that the performance ot programs in virtual memory environments can be signifi· cantly Improved by restT".J.cturing the programs. I.e. by modifying their block-la-page or block-ta-segment mapping. This evidence also points aut that the so-caned strategy-o'r'iented algorithms. which base their decisions on the lmoW"ledge of the memory management strategy under which the pro· gram will run, are more efficient than those algorithms whicr ~ do not take this strategy into account. We present here some thecretical argwnents to explain Why strateg~' oriented algorithms perform better than other program restructuring algo-rithms and deterI!1ine the conditions under which these algorithms are op· timUI:::1. In particular. we prove that the algorith.."11s oriented towacds the working set or sampled working set policy are optimum when applied to pro-grams haVing no more than two blocks per page. an...
Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks ... more Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks among several repair nodes. These repair nodes keep in their buffers all recently received packets and perform error recovery for their receiver nodes. This work addresses two open issues in tree-based protocols. The first is how to construct a logical tree in an efficient manner. We propose three efficient hybrid schemes for constructing a well-organized logical tree with reasonable message and time overhead. The second open issue is when to discard packets from the buffers of repair nodes. Discarding packets that might still be needed is unacceptable, because it would force the receiver nodes to contact the sender node whenever one of them needs a retransmission of a discarded packet. Schemes addressing this issue can be broadly divided into ACK-based and NAK-based schemes. ACK-based schemes require each repair node to receive one acknowledgement from each of its receiver node for each...
One way to reduce the cost of VOD is to schedule repeated broadcasts of the videos that are likel... more One way to reduce the cost of VOD is to schedule repeated broadcasts of the videos that are likely to be watched by many viewers rather than waiting for individual requests. This technique is known as video broadcasting. The savings that can be achieved are considerable, as it is often the case that 40 percent of the demand is for a small number, say, 10 to 20, of hot videos [3]. Depending on the frequency at which these videos are rebroadcast, customers may have to wait between a few minutes to, say, half an hour before watching the video of their choice. Hence this type of service can either be referred to as near video on demand (NVOD) or enhanced pay per view (EPPV).
2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021
Large data storage systems often use Reed-Solomon erasure codes to protect their static data agai... more Large data storage systems often use Reed-Solomon erasure codes to protect their static data against triple or even quadruple device failures. A main drawback of this approach is the high cost of recovering the contents of failed devices, as it requires accessing the contents of a large number of surviving devices. We present a three-dimensional RAID organization that adds vertical parity devices to a stack of identical two-dimensional RAID arrays. These new vertical parity devices will let the organization recover faster from all single device failures while greatly reducing the risk of data loss. Depending on the way the vertical parities are defined, the new arrays will either toler-ate all triple failures and more than 99.9 percent of all quadruple failures, or all quintuple failures and more than 99.995 percent of all sextuple failures.
Two-dimensional RAID arrays maintain separate row and column parities for all their disks. Depend... more Two-dimensional RAID arrays maintain separate row and column parities for all their disks. Depending on their organization, they can tolerate between two and three concurrent disk failures without losing any data. We propose to enhance the robustness of these arrays by replacing a small fraction of these drives with storage class memory devices, and demonstrate how such a pairing is
Considerable expertr::lental eVidence has been accumulated showing that the performance ot progra... more Considerable expertr::lental eVidence has been accumulated showing that the performance ot programs in virtual memory environments can be signifi· cantly Improved by restT".J.cturing the programs. I.e. by modifying their block-la-page or block-ta-segment mapping. This evidence also points aut that the so-caned strategy-o'r'iented algorithms. which base their decisions on the lmoW"ledge of the memory management strategy under which the pro· gram will run, are more efficient than those algorithms whicr ~ do not take this strategy into account. We present here some thecretical argwnents to explain Why strateg~' oriented algorithms perform better than other program restructuring algo-rithms and deterI!1ine the conditions under which these algorithms are op· timUI:::1. In particular. we prove that the algorith.."11s oriented towacds the working set or sampled working set policy are optimum when applied to pro-grams haVing no more than two blocks per page. an...
Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks ... more Tree-based reliable multicast protocols provide scalability by distributing error-recovery tasks among several repair nodes. These repair nodes keep in their buffers all recently received packets and perform error recovery for their receiver nodes. This work addresses two open issues in tree-based protocols. The first is how to construct a logical tree in an efficient manner. We propose three efficient hybrid schemes for constructing a well-organized logical tree with reasonable message and time overhead. The second open issue is when to discard packets from the buffers of repair nodes. Discarding packets that might still be needed is unacceptable, because it would force the receiver nodes to contact the sender node whenever one of them needs a retransmission of a discarded packet. Schemes addressing this issue can be broadly divided into ACK-based and NAK-based schemes. ACK-based schemes require each repair node to receive one acknowledgement from each of its receiver node for each...
One way to reduce the cost of VOD is to schedule repeated broadcasts of the videos that are likel... more One way to reduce the cost of VOD is to schedule repeated broadcasts of the videos that are likely to be watched by many viewers rather than waiting for individual requests. This technique is known as video broadcasting. The savings that can be achieved are considerable, as it is often the case that 40 percent of the demand is for a small number, say, 10 to 20, of hot videos [3]. Depending on the frequency at which these videos are rebroadcast, customers may have to wait between a few minutes to, say, half an hour before watching the video of their choice. Hence this type of service can either be referred to as near video on demand (NVOD) or enhanced pay per view (EPPV).
2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021
Large data storage systems often use Reed-Solomon erasure codes to protect their static data agai... more Large data storage systems often use Reed-Solomon erasure codes to protect their static data against triple or even quadruple device failures. A main drawback of this approach is the high cost of recovering the contents of failed devices, as it requires accessing the contents of a large number of surviving devices. We present a three-dimensional RAID organization that adds vertical parity devices to a stack of identical two-dimensional RAID arrays. These new vertical parity devices will let the organization recover faster from all single device failures while greatly reducing the risk of data loss. Depending on the way the vertical parities are defined, the new arrays will either toler-ate all triple failures and more than 99.9 percent of all quadruple failures, or all quintuple failures and more than 99.995 percent of all sextuple failures.
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Papers by Jehan-Francois Paris