Abstract: A fluorescent water-soluble polycationic chitosan polymer having a general formula (I) and salts thereof: wherein a is an integer between 220 and 11,200; R1 and R2 are independently selected from the group consisting of CH3CO and H, provided that at least 25% of the O-positions of the chitosan polymer structure is substituted with CH3CO; R7 is selected from the group consisting of CH3CO, H and Dye, provided that (i) at least one Dye residue is present in the chitosan polymer structure, (ii) and at least 15% of the N-positions of the chitosan polymer structure is substituted with CH3CO; Dye is a polymethine dye, having a general formula (II): wherein W represents 4-8 carbon atoms forming a benzo-condensed or a naphto-condensed ring; R3 and R4 are independently selected from the group consisting of CH2CH3, (CH2)3SO3?, (CH2)3N+(CH3)3; R5 and R6 are independently selected from the group consisting of H, SO3?; Q is selected from the group consisting of wherein D is selected from the group

Abstract: A data storage system includes multiple head nodes and data storage sleds. Volume data is replicated between a primary and one or more secondary head nodes for a volume partition and is further flushed to a set of mass storage devices of the data storage sleds. Volume metadata is maintained in a primary and one or more secondary head nodes for a volume partition and is updated in response to volume data being flushed to the data storage sleds. Also, the primary and secondary head nodes store check-points of volume metadata to the data storage sleds, wherein in response to a failure of a primary or secondary head node for a volume partition, a replacement secondary head node for the volume partition recreates a secondary replica for the volume partition based, at least in part, on a stored volume metadata checkpoint.

Abstract: A storage service supports attachment of multiple clients to a distributed storage object and further supports persistent reservations that govern types of access the respective clients are granted with respect to the distributed storage object. In order to efficiently distribute reservation state changes to multiple partitions of the distributed storage object hosted by different data storage units/servers, existing connections are used between the data storage units/servers hosting the partitions of the distributed storage object and the connected clients to propagate reservation state changes.

Abstract: A fiber optic module for installation within patch panel, the fiber optic module comprising a first outer wall with a first rail profile on its outside surface, a second outer wall with a second rail profile on its outside surface, and at least one optical connector. The first outer wall and the second outer wall run parallel to each other. The at least one optical connector is arranged between the first outer wall and the second outer wall. The first rail profile and the second rail profile are complementary to each other such that the fiber optic module may be coupled to an adjacent fiber optic module, wherein the first rail profile of the fiber optic module may be coupled to the second rail profile of the adjacent fiber optic module.

Abstract: A data storage system includes a head node and mass storage devices. The head node is configured to store volume data and flush volume data to the mass storage devices. Additionally, the head node is configured to determine a quantity of data partitions and/or parity partitions to store for a chunk of volume data being flushed to the mass storage devices in order to satisfy a durability guarantee. For chunks of data for which complete copies are also stored in an additional data storage system, the head node is configured to reduce the quantity of data partitions and/or parity partitions stored such that required storage space is reduced while still ensuring that the durability guarantee is satisfied.

Abstract: A storage service supports attachment of multiple clients to a distributed storage object and further supports persistent reservations that govern types of access the respective clients are granted with respect to the distributed storage object. In order to efficiently distribute reservation state changes to multiple partitions of the distributed storage object hosted by different data storage units/servers, existing connections are used between the data storage units/servers hosting the partitions of the distributed storage object and the connected clients to propagate reservation state changes.

Abstract: A block-based storage system hosts logical volumes that are implemented via multiple replicas of volume data stored on multiple resource hosts in different failure domains. Also, the block-based storage service allows multiple client computing devices to attach to a same given logical volume at the same time. In order to prevent unnecessary failovers, a primary node storing a primary replica is configured with a health check application programmatic interface (API) and a secondary node storing a secondary replica determines whether or not to initiate a failover based on the health of the primary replica.

Abstract: A block-based storage system hosts logical volumes that are implemented via multiple replicas of volume data stored on multiple resource hosts in different failure domains. Also, the block-based storage service allows multiple client computing devices to attach to a same given logical volume at the same time. In order to prevent unnecessary failovers, a primary node storing a primary replica is configured with a health check application programmatic interface (API) and a secondary node storing a secondary replica determines whether or not to initiate a failover based on the health of the primary replica.

Abstract: A data storage system includes multiple head nodes and data storage sleds. A control plane of the data storage system designates, for a volume partition, one of the head nodes to function as a primary head node storing a primary replica of the volume partition and designates two or more other head nodes to function as reserve head nodes storing reserve replicas of the volume partition. Additionally, the primary head node causes volume data for the volume partition to be erasure encoded and stored on multiple mass storage devices in different ones of the data storage sleds.

Abstract: A data storage system includes multiple head nodes and data storage sleds. Volume data is replicated between a primary and one or more secondary head nodes for a volume partition and is further flushed to a set of mass storage devices of the data storage sleds. Volume metadata is maintained in a primary and one or more secondary head nodes for a volume partition and is updated in response to volume data being flushed to the data storage sleds. Also, the primary and secondary head nodes store check-points of volume metadata to the data storage sleds, wherein in response to a failure of a primary or secondary head node for a volume partition, a replacement secondary head node for the volume partition recreates a secondary replica for the volume partition based, at least in part, on a stored volume metadata checkpoint.

Abstract: The present disclosure generally relates to creating virtualized block storage devices whose data is replicated across isolated computing systems to lower risk of data loss even in wide-scale events, such as natural disasters. The virtualized device can include at least two volumes, each of which is implemented in a distinct computing system. In the case of a failed volume, a new volume can be created and populated with data from the surviving volume. During population, new writes can continue to be replicated to the new volume. The population process can write data from the surviving volume to the new volume “under” new writes, such that the population process does not overwrite data included in the new writes.

Abstract: The present disclosure generally relates to creating virtualized block storage devices whose data is replicated across isolated computing systems to lower risk of data loss even in wide-scale events, such as natural disasters. The virtualized device can include at least two volumes, each of which is implemented in a distinct computing system. Each volume can be implemented by at least two computing devices, a first of which is configured as a primary device to which reads from and writes to the volume are directed. To ensure consistency in the distributed device, a multi-tier authority service is implemented, in which a cross-computing system authority service designates a volume as having authority to accept writes to the virtualized device, and in which a second tier authority service designates a computing device as having authority to accept writes to the volume.

Abstract: A fiber optic module for installation within patch panel, the fiber optic module comprising a first outer wall with a first rail profile on its outside surface, a second outer wall with a second rail profile on its outside surface, and at least one optical connector. The first outer wall and the second outer wall run parallel to each other. The at least one optical connector is arranged between the first outer wall and the second outer wall. The first rail profile and the second rail profile are complementary to each other such that the fiber optic module may be coupled to an adjacent fiber optic module, wherein the first rail profile of the fiber optic module may be coupled to the second rail profile of the adjacent fiber optic module.

Abstract: A data storage system includes multiple head nodes and data storage sleds. Volume data is replicated between a primary and one or more secondary head nodes for a volume partition and is further flushed to a set of mass storage devices of the data storage sleds. Volume metadata is maintained in a primary and one or more secondary head nodes for a volume partition and is updated in response to volume data being flushed to the data storage sleds. Also, the primary and secondary head nodes store check-points of volume metadata to the data storage sleds, wherein in response to a failure of a primary or secondary head node for a volume partition, a replacement secondary head node for the volume partition recreates a secondary replica for the volume partition based, at least in part, on a stored volume metadata checkpoint.

Abstract: A data storage system includes a head node and mass storage devices. The head node is configured to flush data stored in a storage of the head node to a set of the mass storage devices of the data storage system. A head node may flush both current version data and point-in-time version data to the set of mass storage devices. Also, the data storage system maintains an index that indicates storage locations of data for particular portions of a volume before and after the data is flushed to the set of mass storage devices. In some embodiments an index includes a current version reference for a volume or portion of a volume and one or more point-in-time snapshot references.

Abstract: A block-based storage system hosts logical volumes that are implemented via multiple replicas of volume data stored on multiple resource hosts in different failure domains. Also, the block-based storage service allows multiple client computing devices to attach to a same given logical volume at the same time. In order to prevent unnecessary failovers, a primary node storing a primary replica is configured with a health check application programmatic interface (API) and a secondary node storing a secondary replica determines whether or not to initiate a failover based on the health of the primary replica.

Abstract: A data storage system includes a head node and mass storage devices. The head node is configured to flush data stored in a storage of the head node to a set of the mass storage devices of the data storage system. A head node may flush both current version data and point-in-time version data to the set of mass storage devices. Also, the data storage system maintains an index that indicates storage locations of data for particular portions of a volume before and after the data is flushed to the set of mass storage devices. In some embodiments an index includes a current version reference for a volume or portion of a volume and one or more point-in-time snapshot references.

Abstract: A block-based storage system hosts logical volumes that are implemented via multiple replicas of volume data stored on multiple resource hosts in different failure domains. Also, the block-based storage service allows multiple client computing devices to attach to a same given logical volume at the same time. In order to prevent unnecessary failovers, a primary node storing a primary replica is configured with a health check application programmatic interface (API) and a secondary node storing a secondary replica determines whether or not to initiate a failover based on the health of the primary replica.

Abstract: The present disclosure generally relates to creating virtualized block storage devices whose data is replicated across isolated computing systems to lower risk of data loss even in wide-scale events, such as natural disasters. The virtualized device can include at least two volumes, each of which is implemented in a distinct computing system. In the case of a failed volume, a new volume can be created and populated with data from the surviving volume. During population, new writes can continue to be replicated to the new volume. The population process can write data from the surviving volume to the new volume “under” new writes, such that the population process does not overwrite data included in the new writes.

Abstract: The present disclosure generally relates to creating virtualized block storage devices whose data is replicated across isolated computing systems to lower risk of data loss even in wide-scale events, such as natural disasters. The virtualized device can include at least two volumes, each of which is implemented in a distinct computing system. Each volume can be implemented by at least two computing devices, a first of which is configured as a primary device to which reads from and writes to the volume are directed. To ensure consistency in the distributed device, a multi-tier authority service is implemented, in which a cross-computing system authority service designates a volume as having authority to accept writes to the virtualized device, and in which a second tier authority service designates a computing device as having authority to accept writes to the volume.