Oracle International Corporation

Jia Shi

Kothanda Umamageswaran

Zuoyu Tao

Juan R Loaiza

Alexander Tsukerman

Vijay Sridharan

Selcuk Aya

Alex Tsukerman

Wei Zhang

Yunrui Li

Vinay H Srihari

Boris Erlikhman

Nilesh Choudhury

Wei-Ming Hu

Sumanta Kumar Chatterjee

Richard L Frank

J William Lee

Bharat Chandra Baddepudi

Kiran Badrinarain Goyal

David Friedman

Vijayakrishnan Nagarajan

Scott Martin

Bang Nguyen

Justin Matthew Lewis

Tirthankar Lahiri

Kumar Rajamani

Mahesh Baburao Girkar

Niloy Mukherjee

Krishnan Meiyyappan

Vikram Joshi

Mark Dilman

Jaebock Lee

Neil MacNaughton

Wei Ming Hu

Neil J S MacNaughton

Graham Ivey

Roger J Hansen

Benedicto Elmo Garin, Jr

Hochak Hung

Jonghyun Lee

Vipin Gokhale

Sarat B Kakarla

Semen Ustimenko

Kesavan P Srinivasan

Shih-Yu Huang

Tudor Bosman

Zheren R Zhang

Zuoyo Tao

Mingmin Chen

Huy Nguyen

Arvind Nithrakashvap

Kai Zhang

Masakazu Bando

Salini Selvaraj Kowsalya

Somayeh Sardashti

Yiliang Jin

Zheren Zhang

Juan R Loiza

Kiran B Goyal

Techniques are described for providing one or more clients with direct access to cached data blocks within a persistent memory cache on a storage server. In an embodiment, a storage server maintains a persistent memory cache comprising a plurality of cache lines, each of which represent an allocation unit of block-based storage. The storage server maintains an RDMA table that include a plurality of table entries, each of which maps a respective client to one or more cache lines and a remote access key. An RDMA access request to access a particular cache line is received from a storage server client. The storage server identifies access credentials for the client and determines whether the client has permission to perform the RDMA access on the particular cache line. Upon determining that the client has permissions, the cache line is accessed from the persistent memory cache and sent to the storage server client.

PMEM cache RDMA security

Described is an improved approach to implement fast detection of node death. Instead of just relying on multiple heart beats to fail in order to determine whether a node is dead, the present approach performs an on demand validation using RDMA to determine whether the node is reachable, where the approach of using RDMA is significantly faster than the heartbeat approach.

Fast node death detection

Techniques related to a server-side extension of client-side caches are provided. A storage server computer receives, from a database server computer, an eviction notification indicating that a data block has been evicted from the database server computer's cache. The storage server computer comprises a memory hierarchy including a volatile cache and a persistent cache. Upon receiving the eviction notification, the storage server computer retrieves the data block from the persistent cache and stores it in the volatile cache. When the storage server computer receives, from the database server computer, a request for the data block, the storage server computer retrieves the data block from the volatile cache. Furthermore, the storage server computer sends the data block to the database server computer, thereby causing the data block to be stored in the database server computer's cache. Still further, the storage server computer evicts the data block from the volatile cache.

Server-side extension of client-side caches

Techniques are provided to adjust the behavior of a cache based on a count of cache misses for items recently evicted. In an embodiment, a computer responds to evicting a particular item (PI) from a cache by storing a metadata entry for the PI into memory. In response to a cache miss for the PI, the computer detects whether or not the metadata entry for the PI resides in memory. When the metadata entry for the PI is detected in memory, the computer increments a victim hit counter (VHC) that may be used to calculate how much avoidable thrashing is the cache experiencing, which is how much thrashing would be reduced if the cache were expanded. Either immediately or arbitrarily later, the computer adjusts a policy of the cache based on the VHC's value. For example, the computer may adjust the capacity of the cache based on the VHC.

Detection of avoidable cache thrashing for OLTP and DW workloads

Data blocks are cached in a persistent cache ('NV cache') allocated from as non-volatile RAM ('NVRAM'). The data blocks may be accessed in place in the NV cache of a &#x201c;source&#x201d; computing element by another &#x201c;remote&#x201d; computing element over a network using remote direct memory access (&#x201c;RMDA&#x201d;). In order for a remote computing element to access the data block in NV cache on a source computing element, the remote computing element needs the memory address of the data block within the NV cache. For this purpose, a hash table is stored and maintained in RAM on the source computing element. The hash table identifies the data blocks in the NV cache and specifies a location of the cached data block within the NV cache.

Non-volatile cache access using RDMA

Techniques related to failover to the secondary storage server from a primary storage server of a database server without degrading the performance of servicing storage requests for client applications are provided. In an embodiment, the secondary storage server receives, from the database server, an eviction notification indicating that a set of data blocks has been evicted from a cache. The secondary storage server's memory hierarchy includes a secondary cache and a secondary persistent storage that stores a second copy of the set of data blocks. The secondary storage server persistently stores a copy of data, which is also persistently stored on the primary storage server, which includes a first copy of the set of data blocks. In an embodiment, upon receiving the eviction notification, the secondary storage server retrieves the second copy of the set of data blocks from the secondary persistent storage of the secondary storage server and loads the second copy of the set of data blocks into the secondary cache. After an interruption event, the secondary storage receives a request for a subset of the set of data blocks based on a request for data, at the database server. Upon receiving the request for the subset of the set of data blocks, the second storage server retrieves the subset of the set of data blocks from the second copy of the set of data blocks stored on the secondary cache of the secondary storage server without retrieving any of such data blocks from the second copy of the set of data blocks stored on the persistent storage of the secondary storage server. The second storage server sends the subset of the set of data blocks to the database server.

Secondary storage server caching

A shared storage architecture persistently stores database files in non-volatile random access memories (NVRAMs) of computing nodes of a multi-node DBMS. The computing nodes of the multi-node DBMS not only collectively store database data on NVRAMs of the computing nodes, but also host database server instances that process queries in parallel, host database sessions and database processes, and together manage access to a database stored on the NVRAMs of the computing nodes. To perform a data block read operation from persistent storage, a data block may be transferred directly over a network between NVRAM of a computing node that persistently stores the data block to a database buffer in non-volatile RAM of another computing node that requests the data block. The transfer is accomplished using remote direct memory access ('RDMA).

Database with NVDIMM as persistent storage

A method and apparatus for intelligent network resource manager for distributed computing systems is provided. A first priority is assigned to a first virtual channel set that includes at least two virtual channels of a plurality of virtual channels associated with a physical communication channel. A second priority is assigned to a second virtual channel set that includes at least one virtual channel of the plurality of virtual channels. The first virtual channel set has more virtual channels than the second virtual channel set. Outbound messages of the first priority are directed to virtual channels of the first virtual channel set. Outbound messages of the second priority are directed to virtual channels of the second virtual channel set. The virtual channels are processed in a round-robin order, where processing includes sending the outbound messages over the physical communication channel.

Intelligent network resource manager

A shared storage architecture persistently stores database files in non-volatile random access memories (NVRAMs) of computing nodes of a multi-node DBMS. The computing nodes of the multi-node DBMS not only collectively store database data on NVRAMs of the computing nodes, but also host database server instances that process queries in parallel, host database sessions and database processes, and together manage access to a database stored on the NVRAMs of the computing nodes. To perform a data block read operation from persistent storage, a data block may be transferred directly over a network between NVRAM of a computing node that persistently stores the data block to a database buffer in non-volatile RAM of another computing node that requests the data block. The transfer is accomplished using remote direct memory access ('RDMA). In addition to techniques for performing a data block read operation to NVRAM, computing nodes perform a data block write operation to data blocks stored in NVRAM of the NVRAM shared storage architecture. The data block write operation is referred to herein as a one-sided write because only one database process needs to participate in the writing of a data block to NVRAM in order to successfully commit the write.

Remote one-sided persistent writes

A storage device uses non-volatile memory devices for caching. The storage device operates in a mode referred to herein as write-back mode. In write-back mode, a storage device responds to a request to write data by persistently writing the data to a cache in a non-volatile memory device and acknowledges to the requestor that the data is written persistently in the storage device. The acknowledgement is sent without necessarily having written the data that was requested to be written to primary storage. Instead, the data is written to primary storage later.

Write-back storage cache based on fast persistent memory

Techniques herein are for creating a database snapshot by creating a sparse database. A method involves receiving a creation request to create a sparse database. The creation request has an identity of a parent database. The creation request is processed to create a sparse database. The sparse database has the identity of the parent database. The sparse database does not contain data copied from the parent database. A write request to write data into the sparse database is received. The write request is processed by writing the data into the sparse database. The parent database does not receive the data.

Database snapshots

No-loss rapid recovery performs resynchronization efficiently while concurrently allowing availability to mirrored data on the storage device. No-loss rapid recovery has two stages and involves storage devices that have both a non-volatile cache and primary storage and that operate as mirror buddies. The first stage is referred to herein as the buddy-retention stage. During the buddy-retention stage, writes to mirrored data are not performed on the offline mirror buddy but are performed on the online mirror buddy. The mirrored data changed in the online mirrored buddy is retained in the non-volatile cache of the retention buddy. The next stage is referred to herein as the rapid resynchronization stage. In this stage, the changed mirrored data retained by the retention buddy for no-loss rapid recovery is used to resynchronize the offline buddy. The storage device is resynchronized using the changed mirrored data retained in the cache of the mirror buddy.

Rapid recovery from downtime of mirrored storage device

Techniques herein are for accessing non-materialized blocks of a sparse file. A method involves a storage system receiving a storage command to access a sparse file. A combined content of a set of materialized blocks and a header that identifies one or more non-materialized blocks is assembled. The combined content does not comprise a content of the one or more non-materialized blocks. Responsive to the assembling, the combined content is transferred between the storage system and a computer system.

Sparse file access

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Burlingame, CA, United States of America

Jia Shi