Abstract: Methods and apparatus for equitable distribution of excess shared-resource throughput capacity are disclosed. A first and a second work target are configured to access a shared resource to implement accepted work requests. Admission control is managed at the work targets using respective token buckets. A first metric indicative of the work request arrival rates at the work targets during a time interval, and a second metric associated with the provisioned capacities of the work targets are determined. A number of tokens determined based on a throughput limit of the shared resource is distributed among the work targets to be used for admission control during a subsequent time interval. The number of tokens distributed to each work target is based on the first metric and/or the second metric.

Abstract: Partitions of a hosted computing service may be maintained on a computing node. Processing of requests to access the partition may be limited to constrain capacity utilization to a provisioned amount of capacity reserved for the partition. A second, additional amount of capacity may be associated with the partition and may reflect potential future changes to the provisioned amount of capacity. A sum of provisioned and additional capacities associated with partitions on a computing node may be calculated. The computing node may be ranked, relative to other computing nodes, for maintaining new or relocated partitions based on the sum.

Abstract: Embodiments of the present invention provide methods and devices for multi-user cluster identity authentication, where a key set of a user cluster device is managed using a processor, the key set and an identification code of the key set are distributed to the user cluster device, and when the user cluster device makes a request to access a certain service device, an authentication request is sent to a key management device that includes a digital signature of the user cluster device. The key management device performs identity authentication on the user cluster device, regularly updates the key set and the identification code of the key set using a polling mechanism, and distributes the key set and the identification code to the user cluster device. The user cluster device updates the digital signature using the updated key set and the identification code.

Abstract: Methods and apparatus for equitable distribution of excess shared-resource throughput capacity are disclosed. A first and a second work target are configured to access a shared resource to implement accepted work requests. Admission control is managed at the work targets using respective token buckets. A first metric indicative of the work request arrival rates at the work targets during a time interval, and a second metric associated with the provisioned capacities of the work targets are determined. A number of tokens determined based on a throughput limit of the shared resource is distributed among the work targets to be used for admission control during a subsequent time interval. The number of tokens distributed to each work target is based on the first metric and/or the second metric.

Abstract: Methods and apparatus for burst-mode admission control using token buckets are disclosed. A work request (such as a read or a write) directed to a work target is received. Based on a first criterion, a determination is made that the work target is in a burst mode of operation. A token population of a burst-mode token bucket is determined, and if the population meets a second criterion, the work request is accepted for execution.

Abstract: A database service may maintain tables on behalf of clients and may provision throughput capacity for those tables. A table may be divided into multiple partitions, according to hash of the primary key values for each of the items in the table, and the items in the table may be accessed using the hash of their primary key values. Provisioned throughput capacity for the table may be divided between the partitions and used in servicing requests directed to items in the table. The service (or underlying system) may provide mechanisms for generating skew-related metrics or reports and presenting them to clients via a graphical user interface (GUI). The metrics and reports may indicate the amount of uniformity or skew in the distribution of requests across the key space for the table using histograms, heat maps, or other representations. Clients may initiate actions to correct any skewing via the GUI.

Abstract: Methods and apparatus for compound token buckets usable for burst-mode admission control are disclosed. A peak burst rate and a sustained burst rate of work requests that are to be supported at a work target are determined. The maximum token populations of a peak-burst token bucket and a sustained-burst token bucket are configured, based on the peak burst rate and the sustained burst rate respectively. In response to receiving a work request directed at the work target, a determination to accept the work request for execution is made based at least in part on the token population of the peak-burst token bucket and/or the sustained-burst token bucket.

Abstract: An automated system may be employed to perform detection, analysis and recovery from faults occurring in a distributed computing system. Faults may be recorded in a metadata store for verification and analysis by an automated fault management process. Diagnostic procedures may confirm detected faults. The automated fault management process may perform recovery workflows involving operations such as rebooting faulting devices and excommunicating unrecoverable computing nodes from affected clusters.

Abstract: A database management system may be operated by a third-party provider that hosts the system in a datacenter and provides access to the system to end users on behalf of various entities. Limits on total capacity consumption may be imposed, but may result in service outages when capacity consumption exceeds those limits. Requests to perform operations on the system may be classified. The request classifications may be associated with policies for admitting or rejecting the request. One or more token buckets representative of capacity available to the request to perform the operation may be used to determine to admit the request and updated based on the cost of performing the operation.

Abstract: Methods and apparatus for token-sharing mechanisms for burst-mode operations are disclosed. A first and a second token bucket are respectively configured for admission control at a first and a second work target. A number of tokens to be transferred between the first bucket and the second bucket, as well as the direction of the transfer, are determined, for example based on messages exchanged between the work targets. The token transfer is initiated, and admission control decisions at the work targets are made based on the token population resulting from the transfer.

Abstract: Methods and apparatus for token-sharing mechanisms for burst-mode operations are disclosed. A first and a second token bucket are respectively configured for admission control at a first and a second work target. A number of tokens to be transferred between the first bucket and the second bucket, as well as the direction of the transfer, are determined, for example based on messages exchanged between the work targets. The token transfer is initiated, and admission control decisions at the work targets are made based on the token population resulting from the transfer.

Abstract: Methods and apparatus for burst-mode admission control using token buckets are disclosed. A work request (such as a read or a write) directed to a work target is received. Based on a first criterion, a determination is made that the work target is in a burst mode of operation. A token population of a burst-mode token bucket is determined, and if the population meets a second criterion, the work request is accepted for execution.

Abstract: Methods and apparatus for token-based pricing policies for burst-mode operations are disclosed. A pricing policy to be applied to token population changes at a token bucket used for admission control during burst-mode operations at a work target is determined. Over a time period, changes to the token population of that bucket are recorded. A billing amount to be charged to a client is determined, based on the recorded changes in token population and an associated pricing amount indicated in the pricing policy.

Abstract: Methods and apparatus for equitable distribution of excess shared-resource throughput capacity are disclosed. A first and a second work target are configured to access a shared resource to implement accepted work requests. Admission control is managed at the work targets using respective token buckets. A first metric indicative of the work request arrival rates at the work targets during a time interval, and a second metric associated with the provisioned capacities of the work targets are determined. A number of tokens determined based on a throughput limit of the shared resource is distributed among the work targets to be used for admission control during a subsequent time interval. The number of tokens distributed to each work target is based on the first metric and/or the second metric.

Abstract: Methods and apparatus for compound token buckets usable for burst-mode admission control are disclosed. A peak burst rate and a sustained burst rate of work requests that are to be supported at a work target are determined. The maximum token populations of a peak-burst token bucket and a sustained-burst token bucket are configured, based on the peak burst rate and the sustained burst rate respectively. In response to receiving a work request directed at the work target, a determination to accept the work request for execution is made based at least in part on the token population of the peak-burst token bucket and/or the sustained-burst token bucket.

Abstract: A database management system may be operated by a third-party provider that hosts the system in a datacenter and provides access to the system to end users on behalf of various entities. Limits on total capacity consumption may be imposed, but may result in service outages when capacity consumption exceeds those limits. Requests to perform operations on the system may be classified. The request classifications may be associated with policies for admitting or rejecting the request. One or more token buckets representative of capacity available to the request to perform the operation may be used to determine to admit the request and updated based on the cost of performing the operation.

Abstract: An improved skeletal iron catalyst is provided for use in Fischer-Tropsch synthesis reactions for converting CO and H2 to hydrocarbon products. The skeletal iron catalyst is manufactured using iron and a removable non-ferrous component such as aluminum. The iron and removable non-ferrous component are mixed together to form a precursor catalyst and then a portion of the removable non-ferrous component is removed to leave a skeletal iron catalyst. One or more first promoter metals and optionally one or more second promoter metals are incorporated into the skeletal iron catalyst either by blending the promoter into the precursor catalyst during the formation thereof or by depositing the promoter on the skeletal iron. The first promoter metals comprises a metal selected from the group consisting of titanium, zirconium, vanadium, cobalt, molybdenum, tungsten, and platinum-group metals.

Abstract: An improved skeletal iron catalyst is provided for use in Fischer-Tropsch synthesis reactions for converting CO and H2 to hydrocarbon products. The skeletal iron catalyst is manufactured using iron and a removable non-ferrous component such as aluminum. The iron and removable non-ferrous component are mixed together to form a precursor catalyst and then a portion of the removable non-ferrous component is removed to leave a skeletal iron catalyst. One or more first promoter metals and optionally one or more second promoter metals are incorporated into the skeletal iron catalyst either by blending the promoter into the precursor catalyst during the formation thereof or by depositing the promoter on the skeletal iron. The first promoter metals comprises a metal selected from the group consisting of titanium, zirconium, vanadium, cobalt, molybdenum, tungsten, and platinum-group metals.

Abstract: Promoted skeletal iron catalysts are provided which contain 70-90 wt % iron together with promoters 0-5.0 wt. % copper, 0.1-10.0 wt. % manganese, and 0.1-3.0 wt. % potassium, with the balance being aluminum. The catalysts are prepared by mixing the metal chips or powders uniformly together, then melting and rapidly quenching the molten metals to form a solid metal alloy precursor including the promotor metals except potassium, removing most of the aluminum by caustic extraction/leaching to provide a base skeletal iron form, then loading the potassium promoter from a suitable potassium alcohol solution promoter. After evaporation of the solvent, the promoted skeletal iron catalyst is activated by contact with hydrogen. The promoted skeletal iron catalysts are utilized for F-T synthesis processes at 10-30 wt % catalyst concentration, 200-350° C. temperature, 1.0-3.0 Mpa pressure and gas hourly space velocity of 0.5-5.0 L/gcat-h to produce desired hydrocarbon liquid products.

Abstract: Process and economic advantages are achieved by the integration of a Fischer Tropsch process for hydrocarbon liquids production as a retrofit in an installation for the production of ammonia fertilizer from fossil fuel derived syngas. Utilization of most of the CO and part of the H2 in the syngas stream during Fischer-Tropsch synthesis as the first step in the integrated process produces hydrocarbon products while the F-T effluent containing unreacted hydrogen gas at the necessary ratio of H2/N2 is used in the second step of ammonia synthesis. The overall product slate as appropriate for maximum economic performance of the installation is thus achieved.