Abstract: Disclosed herein are techniques for maintaining a secure execution environment on a server. In one embodiment, the server includes a non-volatile memory storing firmware, a programmable security logic coupled to the non-volatile memory, an adapter device coupled to the programmable security logic, and a processor communicatively coupled to the non-volatile memory via the programmable security logic. The adapter device and/or the programmable security logic can verify the firmware in the non-volatile memory while holding the processor and/or a baseboard management controller (BMC) in power reset, release the processor and the BMC from reset to boot the processor and the BMC after the firmware is verified, and then disable communications between the processor and the BMC and deny at least some requests to write to the non-volatile memory by the processor or the BMC.

Abstract: Methods and related systems conduct a capacity check of a battery via a partial discharge cycle. A method of estimating a total capacity of a battery includes partially discharging the battery at a controlled discharge rate so as to discharge an amount of energy from the battery over a period of time. An output voltage of the battery is measured during the period of time. A total capacity of the battery is estimated based on the amount of energy discharged from the battery during the partial discharge cycle and the output voltage of the battery measured during the partial discharge cycle.

Abstract: Technologies are provided for dynamically changing a size of a cache region of a storage device. A storage device controller writes data to the cache region of the storage device using a particular storage format. The storage device controller then migrates the cached data to a storage region of the device, where the data is written using a different storage format. A dynamic cache manager monitors input and output activity for the storage device and dynamically adjusts a size of the cache region to adapt to changes in the input and/or output activity. The dynamic cache manager can also adjust a size of the storage region. The storage device controller can automatically detect that the storage device has dynamic cache support and configure the storage device by creating the cache region and the storage region on the device.

Abstract: A rack-mountable computer system directs separate portions of a cooling airflow from an inlet air plenum in the computer system interior through separate air passages to remove heat from separate portions of a set of heat-producing components. The air passages can preclude a portion of cooling airflow removing heat from a component from being preheated by another component. Plenums and air passages can be established through the arrangement of components in the interior. Components can be arranged in progressive offsets throughout the depth of the interior to vary plenum flow area throughout the depth, which can progressively impede and redirect airflow through the inlet plenum into the air passages. Arrangements can include an angled row, a staggered configuration, etc. The computer system can include a chassis which can translate, while maintaining operation of hot-pluggable electronic components coupled throughout the depth, to enable swapping of hot-pluggable electronic components throughout the interior.

Abstract: Disclosed are various embodiments of power source redundancy in a power supply for a rack mounted computing device. The power supply includes a plurality of AC power converters configured to receive power from corresponding power sources. A first AC power converter provides DC power to a common DC bus of the power supply. A second AC power converter provides DC power to the common DC bus in response to a change in the voltage level provided by the first AC power converter.

Abstract: A server rack comprises a plurality of slots and a plurality of computing devices. Individual ones of the computing devices are mounted within individual ones of the slots. The server rack also comprises a plurality of slot-level thermal regulation systems. At least one of the slot-level thermal regulation systems comprises a louver corresponding to a particular slot and located between a particular computing device mounted within the particular slot and at least one fan configured to facilitate airflow through the server rack. The louver is configured to regulate airflow through the particular computing device. The at least one slot-level thermal regulation system further comprises a thermally activated unit located in an exhaust flow of the particular computing device and configured to change the angle of the louver in response to a change in thermal energy of the exhaust flow.

Abstract: A rack-mountable computer system enables an airflow that cools components in an upstream portion of the computer system interior to be cooled through mixing with a bypass airflow downstream of the components in the upstream portion. The mixed airflow can cool components in a downstream portion of the interior. The bypass airflow is directed by a bypass plenum that is unencompassed by the separate plenum that directs the airflow to cool the upstream portion components. The bypass plenum can be at least partially established by an external surface the computer system and one or more external structures, including an external surface of an adjacently mounted computer system. Relative flow rates through the separate plenums can be adjusted, via flow control elements, to separately control heat removal from components upstream and downstream of the air mixing, based at least in part upon air temperatures in the separate interior portions.

Abstract: A system includes a rack and one or more server systems mounted in the rack. A server system includes a chassis with one or more arrays of devices in the chassis. Each array includes mass storage devices and a server device mounted in the array within the chassis of the server system. The server device occupies no more than an equivalent volume of space in the chassis as one of the mass storage devices. A set of mass storage devices of an array and the server device of the array form a logical node, and a server system may include multiple logical nodes in the same chassis. Each array of devices may be located in a sled that can move into and out of the chassis of the server system.

Abstract: A computing system providing virtual computing services may maintain a fleet of servers that host virtual machine instances having a wide variety of types and configurations. A service provider may rent processor and memory capacity by defining and offering various virtual machine instances to clients. Each virtual machine instance may include one or more virtual CPUs and a fixed amount of virtualized memory allocated to each virtual CPU, dependent on a predefined ratio between virtual CPU capacity and virtualized memory capacity for the instance type. Each server may include a custom, non-standard sized physical memory module containing memory devices of multiple technologies, types, or sizes on the same printed circuit board. By including custom memory modules, rather than relying only on standard memory modules, the service provider system may implement virtual machines having finer grained options for processor and memory capacity combinations, and may avoid stranding rentable resources.

Abstract: A system for performing computing operations includes a rack, one or more shelves coupled to the rack, and two or more computing modules. Each computing module may include a chassis, one or more circuit board assemblies in a primarily vertical orientation, and one or more hard disk drives in a primarily vertical orientation. The circuit board assemblies and the hard disk drives are coupled to the chassis of the computing module.

Abstract: A system includes a rack and one or more server systems mounted in the rack. A server system includes at least one sever node and each server node includes an array of devices including mass storage devices and at least one server device. Segments of the array of devices of a particular server node are mounted in sub-node chassis that include intra node connectors. Multiple sub-node chassis that each include devices such as mass storage devices or server devices of the sever node couple together via the intra node connectors when installed in a server system chassis to form a server node. Each server node of a server system may be a separate logical node. Also, the sub-node chassis of a server node may be configured for vertical airflow through the sub-node chassis in addition to cross airflow.

Abstract: Technologies are provided for dynamically changing a size of a cache region of a storage device. A storage device controller writes data to the cache region of the storage device using a particular storage format. The storage device controller then migrates the cached data to a storage region of the device, where the data is written using a different storage format. A dynamic cache manager monitors input and output activity for the storage device and dynamically adjusts a size of the cache region to adapt to changes in the input and/or output activity. The dynamic cache manager can also adjust a size of the storage region. The storage device controller can automatically detect that the storage device has dynamic cache support and configure the storage device by creating the cache region and the storage region on the device.

Abstract: Technologies are provided for storing data by alternating the performance of data write operations using multiple clusters of storage devices. Data is written to internal buffers of storage devices in one cluster while data stored in buffers of storage devices in another cluster is transferred to the storage devices' permanent storages. When available buffer capacity in a cluster falls below a specified threshold, data write commands are no longer sent the cluster and the storage devices in the cluster transfer data stored in their buffers to their permanent storages. While the data is being transferred, data write commands are transmitted to other clusters. When the data transfer is complete, the storage devices in the cluster can be scheduled to receive data write commands again. A cluster can be selected for performing a given data write request by matching the attributes of the cluster to parameters of the data write request.

Abstract: A rack-mountable computer system directs separate portions of a cooling airflow from an inlet air plenum in the computer system interior through separate air passages to remove heat from separate portions of a set of heat-producing components. The air passages can preclude a portion of cooling airflow removing heat from a component from being preheated by another component. Plenums and air passages can be established through the arrangement of components in the interior. Components can be arranged in progressive offsets throughout the depth of the interior to vary plenum flow area throughout the depth, which can progressively impede and redirect airflow through the inlet plenum into the air passages. Arrangements can include an angled row, a staggered configuration, etc. The computer system can include a chassis which can translate, while maintaining operation of hot-pluggable electronic components coupled throughout the depth, to enable swapping of hot-pluggable electronic components throughout the interior.

Abstract: A computing system includes a circuit board assembly and multiple expansion cards connected to one another and also connected to the circuit board assembly. The connected expansion cards form a modular expansion card bus that allows the expansion cards to communicate between each other without routing the communications through the circuit board assembly. In some embodiments, the expansion cards are mounted on a tray that includes mounting pins that engage mounting slots of the expansion cards, allowing for simple installation of various combinations of expansion cards connected together to form a modular expansion card bus.

Abstract: A system for storing data includes a discrete cooling module that can enable discrete cooling of mass storage devices installed in the chassis interior of a data storage module coupled to a rack. The discrete cooling module includes an air moving device and an air cover. The air moving device can induce and airflow through the chassis interior of the data storage module to remove heat from heat producing components of mass storage devices installed in the chassis interior. The air cover directs the airflow through the chassis interior. The discrete cooling module can isolate rotational vibrations generated by the air moving device from the mass storage devices installed in the chassis. Partial isolation can include indirectly coupling the discrete cooling module to the chassis via directly coupling with the rack.

Abstract: A system includes a rack and one or more server systems mounted in the rack. A server system includes a chassis with one or more arrays of devices in the chassis. Each array includes mass storage devices and a server device mounted in the array within the chassis of the server system. The server device occupies no more than an equivalent volume of space in the chassis as one of the mass storage devices. A set of mass storage devices of an array and the server device of the array form a logical node, and a server system may include multiple logical nodes in the same chassis. Each array of devices may be located in a sled that can move into and out of the chassis of the server system.

Abstract: A rack-mountable computer system enables an airflow that cools components in an upstream portion of the computer system interior to be cooled through mixing with a bypass airflow downstream of the components in the upstream portion. The mixed airflow can cool components in a downstream portion of the interior. The bypass airflow is directed by a bypass plenum that is unencompassed by the separate plenum that directs the airflow to cool the upstream portion components. The bypass plenum can be at least partially established by an external surface the computer system and one or more external structures, including an external surface of an adjacently mounted computer system. Relative flow rates through the separate plenums can be adjusted, via flow control elements, to separately control heat removal from components upstream and downstream of the air mixing, based at least in part upon air temperatures in the separate interior portions.

Abstract: A computing system providing virtual computing services may maintain a fleet of servers that host virtual machine instances having a wide variety of types and configurations. A service provider may rent processor and memory capacity by defining and offering various virtual machine instances to clients. Each virtual machine instance may include one or more virtual CPUs and a fixed amount of virtualized memory allocated to each virtual CPU, dependent on a predefined ratio between virtual CPU capacity and virtualized memory capacity for the instance type. Each server may include a custom, non-standard sized physical memory module containing memory devices of multiple technologies, types, or sizes on the same printed circuit board. By including custom memory modules, rather than relying only on standard memory modules, the service provider system may implement virtual machines having finer grained options for processor and memory capacity combinations, and may avoid stranding rentable resources.

Abstract: A system for performing computing operations includes a rack, one or more shelves coupled to the rack, and two or more computing modules. Each computing module may include a chassis, one or more circuit board assemblies in a primarily vertical orientation, and one or more hard disk drives in a primarily vertical orientation. The circuit board assemblies and the hard disk drives are coupled to the chassis of the computing module.