Roman Pletka

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Write amplification is a critical factor limiting the random write performance and write endurance in storage devices based on NAND-flash memories such as solid-state drives (SSD). The impact of garbage collection on write amplification is influenced by the level of over-provisioning and the choice of reclaiming policy. In this paper, we present a novel(More)
Storage systems are increasingly subject to attacks. Cryptographic file systems mitigate the danger of exposing data by using encryption and integrity protection methods and guarantee end-to-end security for their clients. This paper describes a generic design for cryptographic file systems and its realization in a distributed storage-area network (SAN)(More)
Active Queue Management (AQM) tries to find a delicate balance between two antagonistic Internet queuing requirements: First, buffer space should be maximized to accommodate the possibly huge transient bursts; second, buffer occupation should be minimum so as not to introduce unnecessary endto-end delays. Traditional AQM mechanisms have been built on(More)
Today’s known and widely used active queue management (AQM) schemes do not differentiate between packets from responsive (e.g., TCP sessions) and non-responsive traffic (e.g., UDP). This results in further widening the gap of unfair advantage already inherent to non-responsive traffic, as the responsive sender will significantly reduce its future transmit(More)
Interest in distributed storage is fueled by demand for reliability and resilience combined with ubiquitous availability. Peer-to-peer (P2P) storage networks are known for their decentralized control, self-organization, and adaptation. Advanced searching for documents and resources remains an open problem. The flooding approach favored by some P2P networks(More)
A filesystem-level storage cloud offers network-filesystem access to multiple customers at low cost over the Internet. In this paper, we investigate two alternative architectures for achieving multi-tenancy securely and efficiently in such storage cloud services. They isolate customers in virtual machines at the hypervisor level and through mandatory(More)
In this paper, we present five case studies of advanced networking functions that detail how a network processor (NP) can provide high performance and also the necessary flexibility compared with Application-Specific Integrated Circuits (ASICs). We first review the basic NP system architectures, and describe the IBM PowerNP architecture from a data-plane as(More)
This paper addresses the problem of configuring active queue management systems (e.g. WRED and RIO) for service level specifications in Internetworks. In particular, we focus on Assured Forwarding (AF) for non-responsive flows in Differentiated Services networks. The difficulty is to determine the correct queue level thresholds that will result in correct(More)
Byte-code representations in active networks provide architectural neutrality and code compactness; however, the resulting execution speed is typically poor due to interpretation overhead. This paper shows that the performance of capsule-based active networks can benefit from compiling active network programs into native network processor instructions at(More)
Network processors have been developed to ease the implementation of new network protocols in high-speed routers. Being embedded in network interface cards, they enable extended packet processing at link speed as is required, for instance, for active network nodes. Active network nodes start using network processors for extended packet processing close to(More)