Vmware, Inc.

Vwware, Inc.

Yiqi Xu

Enning Xiang

Eric Shannon Knauft

Pascal Renauld

Ojan Thornycroft

Asit Desai

Varun A Shah

Xiaochuan Shen

Pratik Shridhar Desai

Yizhou Luo

Zhihao Yao

Sandeep Rangaswamy

Mansi Shah

Xin Liang Li

Venkata Ramanan

System and method for managing different classes of storage input/output (I/O) requests for a two-phase commit operation in a distributed storage system assigns reserved log sequence values to each of storage I/O requests of a first class, which are added to a two-phase commit queue. The reserved log sequence values of the storage I/O requests of the first class in the two-phase commit queue are assigned to some of the storage I/O requests of the second class, which are added to the two-phase commit queue.

Two-phase commit using reserved log sequence values

The disclosure herein describes performing resynchronization ('resync') jobs in a distributed storage system based on a parallelism policy. A resync job is obtained from a queue and input/output (I/O) resources that will be used during execution of the resync job are identified. Available bandwidth slots of each I/O resource of the identified I/O resources are determined. The parallelism policy is applied to the identified I/O resources and the available bandwidth slots. Based on the application of the parallelism policy, a bottleneck resource of the I/O resources is determined and a parallel I/O value is calculated based on the available bandwidth slots of the bottleneck resource, wherein the parallel I/O value indicates a quantity of I/O tasks that can be performed in parallel. The resync job is executed using the I/O resources, the execution of the resync job including performance of I/O tasks in parallel based on the parallel I/O value.

Performing resynchronization jobs in a distributed storage system based on a parallelism policy

The disclosure herein describes enhancing data durability of a base component using a delta component. A delta component is generated based on the base component becoming unavailable. The delta component is configured to include unwritten storage space with an address space matching the base component and a tracking bitmap associated with data blocks of the address space of the delta component. Write operations targeted for the base component are routed to the delta component. Based on the routed write operations, bits associated with data blocks affected by the write operations are changed in the tracking bitmap. Based on the base component becoming available, data blocks affected by routed write operations are identified based on the tracking bitmap and the identified data blocks are synchronized from the delta component to the base component. The delta component is then removed.

Synchronizing a stale component of a distributed object using a delta component during maintenance

Hybrid synchronization using a shadow component includes detecting a first component of a plurality of mirrored components of a distributed data object becoming unavailable. The mirrored components include a delta component (a special shadow component) and a regular mirror (shadow) component. The delta component indicates a shorter history of changes to data blocks of a log-structured file system (LFS) than is indicated by the regular mirror component. During the unavailability of the first component, at least one write I/O is committed by the delta component. The commit is tracked by the delta component in a first tracking bitmap associated with the delta component. Based at least on detecting the first component becoming available, the first component is synchronized with data from the delta component, based at least on changed data blocks indicated in the first tracking bitmap.

Hybrid synchronization using a shadow component

The disclosure herein describes enhancing data durability of a base component of a data object using an unplanned delta component during transient fault unavailability. A base component of a data object becoming unavailable due to a transient fault is detected. A delta component associated with the base component is generated, wherein the delta component includes unwritten storage space with an address space and a tracking bitmap including a plurality of bits associated with data blocks of the address space of the delta component. The stale LSN with which the base component is associated is assigned to the delta component and the delta component is synchronized with an active component of the data object based on the assigned stale LSN. The delta component records write I/O targeted for the base component and, based on detecting the base component becoming available, the base component is synchronized with the delta component.

Maintaining durability of a data object using unplanned delta components during transient failures

The disclosure herein describes tracking changes to a stale component using a synchronization bitmap. A first component of a plurality of mirrored components of the distributed data object becomes available from an unavailable state, and a stale log sequence number (LSN) and a last committed LSN are identified. A synchronization bitmap of the first component associated with a range of LSNs (e.g., from the stale LSN to the last committed LSN) is created and configured to track changes to data blocks of the first component. A second component is identified based on the second component including a tracking bitmap associated with an LSN that matches the stale LSN of the first component. The first component is synchronized with data from the second component based on, wherein the synchronizing includes updating the synchronization bitmap to track changes made to data blocks of the first component.

Synchronizing changes to stale components of a distributed object using synchronization bitmaps

A method of ensuring atomicity of transactions across a plurality of active hosts in a distributed environment, is provided. The method generally includes receiving, from a client, a second request to commit a second transaction subsequent to receiving a first request to commit a first transaction; assigning a second prepare identifier (ID) to the second transaction, wherein the second prepare ID assigned to the second transaction is greater than a first prepare ID assigned to the first transaction; transmitting, to the plurality of active hosts, instructions to prepare for committing the second transaction, the instructions including the second prepare ID; receiving, from each host, an acknowledgement indicating successful preparation for committing the second transaction; and transmitting, to the plurality of active hosts, instructions to commit the second transaction prior to receiving, from each host, an acknowledgement indicating successful preparation for committing the first transaction.

Jitter-tolerant distributed two-phase commit (2PC) systems

The disclosure herein describes placing delta components of a base component in target fault domains. One or more delta components are generated. When a first fault domain that lacks a sibling component of the base component is identified, the first fault domain is selected as a single delta target fault domain and a single delta component is placed on the single delta target fault domain. When a second fault domain that includes a first sibling component of the base component is identified and a third fault domain that includes a second sibling component of the base component is identified, the second fault domain and the third fault domain are selected as a first double delta target fault domain and a second double delta target fault domain, and a first double delta component and a second double delta component are placed on the first and second double delta target fault domains.

Identifying fault domains for delta components of a distributed data object

An efficient scheduling of IOs in a computing system using dynamic bandwidth regulation includes building up a shared regulator to limit the total IOPS scheduling among all IO classes at any given time. Reserved regulators may be used to place limits on the IOPS scheduled for a particular IO class at any given time. An outstanding IO window may also limit the overall number of outstanding IOs, and/or the bytes of outstanding IOs at any particular time. A first stage of IO scheduling may involve enforcing the reserved regulators to limit the IOPS scheduled for particular IO classes. A second stage of IO scheduling may involve enforcing the shared regulator to limit the total IOPS scheduled for all IO classes.

DRR-based two stages IO scheduling algorithm for storage system with dynamic bandwidth regulation

The disclosure herein describes placing a delta component of a base component in a target fault domain. A delta component associated with a base component is generated. The generation includes selecting a first fault domain as a target fault domain for the delta component based on the first fault domain including a witness component associated with the distributed data object of the base component. Otherwise, the generation includes selecting a second fault domain as the target fault domain based on the second fault domain including at least one data component that includes a different address space than the base component. Otherwise, the generation includes selecting a third fault domain as the target fault domain based on the third fault domain being unused. Then, the delta component is placed on the target fault domain, whereby data durability of the distributed data object is enhanced, and available fault domains are preserved.

Identifying a fault domain for a delta component of a distributed data object

The disclosure herein describes enhancing data durability of a base component using multiple delta components. A first and second delta component are generated based on the base component becoming unavailable. A write operation targeted for the base component is routed to the first delta component and to the second delta component. Based on routing the write operation targeted for the base component to the first delta component and to the second delta component, a bit associated with a data block affected by the write operation is changed in each of the tracking bitmaps of the first and second delta components. Based on detecting the base component becoming available, one delta component of the first and second delta components is selected, and the data block affected by the routed write operation is synchronized from the selected delta component to the base component. Later, the first and second delta components are removed.

Synchronizing a stale component of a distributed object using multiple delta components during maintenance

Described herein are methods and systems for the efficient resyncing of stale components of a distributed-computing system. One method includes determining that a first base component at a remote site will go offline. After determining that the first base component at the remote site will go offline, a first delta component is created at the remote site. While the first base component at the remote site is offline, data corresponding to the offline component is collected at the first delta component at the remote site. After collecting data at the first delta component, the collected data is sent to a local site. The method includes determining that the first base component has come back online. In response to determining that the first base component has come back online, the collected data is sent from the first delta component to the first base component via an intra-site network.

Efficient resynchronization for stale components of geographically distributed computing systems

Techniques for intelligently scheduling resynchronization jobs in a distributed object-based storage system are provided. In one set of embodiments, a storage node of the system can create a resynchronization job for a component of an object maintained by the system, where the resynchronization job defines one or more input/output (I/O) operations to be carried out with respect to the component. If a number of currently running resynchronization jobs on the storage node has reached a threshold, the storage node can further determine a priority level associated with the object; add the resynchronization job to an object queue for the object; and if the added resynchronization job is a first job in the object queue, add the object queue as a new queue entry to a global priority queue corresponding to the priority level associated with the object.

Intelligently scheduling resynchronization jobs in a distributed object-based storage system

Computer system and method for managing storage requests in a distributed storage system uses congestion signals associated with storage requests, which are generated based on congestion at local storage of the computer system that supports a virtual storage area network. The storage requests are differentiated between a first class of storage requests and at least one other class of storage requests. For a storage request of the first class of storage requests, an actual ratio of a current average bandwidth of the first class of storage requests to a current average bandwidth of a second class of storage requests is calculated and compared with an expected ratio. The congestion signal associated with the storage request is then adjusted and transmitted to at least one source of storage requests for storage request fairness control.

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Redwood City, CA, United States of America

Yiqi Xu