Abstract: A method, a computing device, and a non-transitory machine-readable medium for booting a virtual machine. In response to a launch or initialization of a virtual machine, the virtual machine may attach a boot volume within a cloud-associated storage system. The boot volume contains a boot program. The boot program is loaded to the virtual machine from the boot volume. The virtual machine uses the boot program to acquire a boot configuration that includes a set of parameters and one or more commands for interfacing with a networked storage system and attaching a root volume within the networked storage system using a network-based storage interface protocol. The virtual machine boots its operating system from the root volume within the networked storage system.

Abstract: A method, a computing device, and a non-transitory machine-readable medium for booting a virtual machine. In response to a launch or initialization of a virtual machine, the virtual machine may attach a boot volume within a cloud-associated storage system. The boot volume contains a boot program. The boot program is loaded to the virtual machine from the boot volume. The virtual machine uses the boot program to acquire a boot configuration that includes a set of parameters and one or more commands for interfacing with a networked storage system and attaching a root volume within the networked storage system using a network-based storage interface protocol. The virtual machine boots its operating system from the root volume within the networked storage system.

Abstract: A write request is received to write a data block having a logical block address to a nonvolatile storage device. The method includes writing a value of the data block to the nonvolatile storage device. The writing includes locating a position in a tree-based data structure that includes first and second nodes. The first node is configured to store a first set of data blocks having logical block addresses in a first numerical range, and the second node is configured to store a second set of data blocks having logical block addresses in a second numerical range. The position is located in the first node or the second node depending on the value of the logical block address. The writing includes storing the value of the data block in the position in the tree-based data structure.

Abstract: A storage system to recover and rewrite overwritten data is described. A Shingled Magnetic Recording (SMR) array subsystem within the storage system writes data to multiple adjacent tracks on a number of storage devices, such as hard drives that support shingled magnetic recording. While writing data, the SMR array subsystem detects that one of the storage devices erroneously overwrote a portion of the data on one or more of the tracks. The SMR array subsystem can recover the overwritten portion of data using other portions of the data written to corresponding tracks on the other storage devices that are part of the array. The recovered data can then be rewritten to the array.

Abstract: A mutable multilevel data structure representing a graph structure may include multiple read-only levels and a single writable level. Each read-only level may include a vertex table (with references to edge tables on the same level or a different level containing elements of adjacency lists for some vertices) and an edge table (with elements of adjacency lists that changed since the previous read-only level). A hybrid variant may switch between a performance-optimized variant (whose edge tables include complete adjacency lists for vertices whose edge sets were modified) and a space-optimized variant (whose edge tables include only newly added adjacency list elements). The vertex tables and/or the writable level may be implemented using copy-on-write arrays, each including an indirection table and multiple fixed-sized data pages. Computations may be run on the read-only levels or on the writable level and read-only levels.

Abstract: Approaches to managing a composite, non-volatile data storage device are described. In one embodiment, a method for managing a composite storage device made up of fast non-volatile storage, such as a solid state device, and slower non-volatile storage, such as a traditional magnetic hard drive, can include maintaining a first data structure, which stores instances of recent access to each unit in a set of units in the fast non-volatile storage device, such as the SSD device and also maintaining a second data structure that indicates whether or not units in the slower storage device, such as the HDD, have been accessed at least a predetermined number of times. In one embodiment, the second data structure can be a queue of Bloom filters.

Abstract: A storage system to recover and rewrite overwritten data is described. A Shingled Magnetic Recording (SMR) array subsystem within the storage system writes data to multiple adjacent tracks on a number of storage devices, such as hard drives that support shingled magnetic recording. While writing data, the SMR array subsystem detects that one of the storage devices erroneously overwrote a portion of the data on one or more of the tracks. The SMR array subsystem can recover the overwritten portion of data using other portions of the data written to corresponding tracks on the other storage devices that are part of the array. The recovered data can then be rewritten to the array.

Abstract: A write request is received to write a data block having a logical block address to a nonvolatile storage device. The method includes writing a value of the data block to the nonvolatile storage device. The writing includes locating a position in a tree-based data structure that includes first and second nodes. The first node is configured to store a first set of data blocks having logical block addresses in a first numerical range, and the second node is configured to store a second set of data blocks having logical block addresses in a second numerical range. The position is located in the first node or the second node depending on the value of the logical block address. The writing includes storing the value of the data block in the position in the tree-based data structure.

Abstract: A mutable multilevel data structure representing a graph structure may include multiple read-only levels and a single writable level. Each read-only level may include a vertex table (which includes references to edge tables on the same level or a different level containing elements of adjacency lists for some vertices) and an edge table (which includes elements of adjacency lists that changed since the previous read-only level). A hybrid variant may switch between a performance-optimized variant (whose edge tables include complete adjacency lists for vertices whose edge sets were modified) and a space-optimized variant (whose edge tables include only newly added adjacency list elements). The vertex tables and/or the writable level may be implemented using copy-on-write arrays, each including an indirection table and multiple fixed-sized data pages. Computations may be run on the read-only levels or on the writable level and read-only levels.

Abstract: Approaches to managing a composite, non-volatile data storage device are described. In one embodiment, a method for managing a composite storage device made up of fast non-volatile storage, such as a solid state device, and slower non-volatile storage, such as a traditional magnetic hard drive, can include maintaining a first data structure, which stores instances of recent access to each unit in a set of units in the fast non-volatile storage device, such as the SSD device and also maintaining a second data structure that indicates whether or not units in the slower storage device, such as the HDD, have been accessed at least a predetermined number of times. In one embodiment, the second data structure can be a queue of Bloom filters.

Abstract: In one embodiment, a method for managing a composite storage device made up of fast non-volatile storage, such as a solid state device, and slower non-volatile storage, such as a traditional magnetic hard drive, can include maintaining a first data structure, which stores instances of recent access to each unit in a set of units in the fast non-volatile storage device, such as the SSD device and also maintaining a second data structure that indicates whether or not units in the slower storage device, such as the HDD, have been accessed at least a predetermined number of times. In one embodiment, the second data structure can be a probabilistic hash table, which has a low required memory overhead but is not guaranteed to always provide a correct answer with respect to whether a unit or block in the slower storage device has been referenced recently.