Netapp, Inc.

Alok Sharma

Kartik Rathnakar

Mukul Sharma

Venkateswarlu Tella

Bipul Raj

Girish Hebbale Venkata Subbaiah

Dnyaneshwar Nagorao Pawar

Satbir Singh

Kiran Nenmeli Srinivasan

Praveen Killamsetti

Rajesh Khandelwal

Sudhanshu Gupta

Vaijayanti Rakshit Bharadwaj

Bharadwaj Vellore Ramesh

Venkata Vijay Chaitanya Challapalli

Sunil Walwaiker

Venkateswarlu Telia

Techniques are provided for asynchronous semi-inline deduplication. A multi-tiered storage arrangement comprises a first storage tier, a second storage tier, etc. An in-memory change log of data recently written to the first storage tier is evaluate to identify a fingerprint of a data block recently written to the first storage tier. A donor data store, comprising fingerprints of data blocks already stored within the first storage tier, is queried using the fingerprint. If the fingerprint is found, then deduplication is performed for the data block to create deduplicated data based upon a potential donor data block within the first storage tier. The deduplicated data is moved from the first storage tier to the second storage tier, such as in response to a determination that the deduplicated data has not been recently accessed. The deduplication is performed before cold data is moved from first storage tier to second storage tier.

Asynchronous semi-inline deduplication

One or more techniques and/or computing devices are provided for inline deduplication. For example, a checksum hash table and/or a block number hash table may be maintained within memory (e.g., a storage controller may maintain the hash tables in-core). The checksum hash table may be utilized for inline deduplication to identify potential donor blocks that may comprise the same data as an incoming storage operation. Data within an in-core buffer cache is eligible as potential donor blocks so that inline deduplication may be performed using data from the in-core buffer cache, which may mitigate disk access to underlying storage for which the in-core buffer cache is used for caching. The block number hash table may be used for updating or removing entries from the hash tables, such as for blocks that are no longer eligible as potential donor blocks (e.g., deleted blocks, blocks evicted from the in-core buffer cache, etc.).

Inline deduplication

It is determined that a first data unit is to be written to a storage device and that the first data unit is associated with a first attribute. In response to determining that the first data unit is associated with the first attribute, a first identifier is selected from a first identifier space and the first identifier is associated with the first data unit. It is determined that a second data unit is to be written to the storage device and that the second data unit is associated with the second attribute. In response to determining that the second data unit is associated with the second attribute, a second identifier is selected from a second identifier space and the second identifier is associated with the second data unit.

Mapping logical identifiers using multiple identifier spaces

Multiple key-value stores may be employed to smooth out random updates (based on the extent ID) to the EMAP database. The updates to the EMAP database occur in a two-stage manner: (i) using an append-only log store for the first stage and (ii) using an on-disk hash store for the second stage. The append-only log store is used to convert the random updates to sequential write operations on the EMAP database. Once full, the contents of the log store are sorted and moved to the on-disk hash store, which holds the updates for a transient period of time to enable batching of the updates. Once sufficient batching of the extent map entries are accumulated, those entries are sorted and moved to the EMAP database. Thereafter, the EMAP database can be scanned to find extent map entries having identical checksum bits to perform data deduplication.

Two-stage front end for extent map database

Described herein is a system and method for retaining deduplication of data blocks of a resulting storage object (e.g., a flexible volume) from a split operation of a clone of a base storage object. The clone may comprise data blocks that are shared with at least one data block of the base storage object and at least one data block that is not shared with at least one data block of the base storage object. The data blocks of the clone that are shared with the base storage object may be indicated to receive a write allocation that may comprise assigning a new pointer to an indicated data block. Each data block may comprise a plurality of pointers comprising a virtual address pointer and a physical address pointer. As such, data blocks of the clone comprising the same virtual address pointer may be assigned a single physical address pointer. Thus, a new physical address pointer is assigned or allocated once to a given virtual address pointer of data blocks of a clone.

Maintaining data block maps of clones of storage objects

An extent map (EMAP) database may include one or more extent map entries configured to map extent IDs to PVBNs. Each extent ID may be apportioned into a most significant bit (MSB) portion, i.e., checksum bits, and a least significant bit (LSB) portion, i.e., duplicate bits. A hash may be applied to the data of the extent to calculate the checksum bits, which illustratively represent a fingerprint of the data. The duplicate bits may be configured to denote any reoccurrence of the checksum bits in the EMAP database, i.e., whether there is an existing extent with potentially identical data in a volume of the aggregate. Each extent map entry may be inserted on a node having one or more key/value pairs, wherein the key is the extent ID and the value is the PVBN. The EMAP database may be scanned and utilized to perform data deduplication.

Data deduplication utilizing extent ID database

Described herein is a system and method for retaining deduplication of data blocks of a resulting storage object (e.g., a flexible volume) from a split operation of a clone of a base storage object. The clone may comprise data blocks that are shared with at least one data block of the base storage object and at least one data block that is not shared with at least one data block of the base storage object. The data blocks of the clone that are shared with the base storage object may be indicated to receive a write allocation that may comprise assigning a new pointer to a indicated data block. Each data block may comprise a plurality of pointers comprising a virtual address pointer and a physical address pointer. As such, data blocks of the clone comprising the same virtual address pointer may be assigned a single physical address pointer. Thus, a new physical address pointer is assigned or allocated once to a given virtual address pointer of data blocks of a clone.

System and method for retaining deduplication in a storage object after a clone split operation

The techniques introduced here provide for enabling deduplication operations for a file system without significantly affecting read performance of the file system due to fragmentation of the data sets in the file system. The techniques include determining, by a storage server that hosts the file system, a level of fragmentation that would be introduced to a data set stored in the file system as a result of performing a deduplication operation on the data set. The storage server then compares the level of fragmentation with a threshold value and determines whether to perform the deduplication operation based on a result of comparing the level of fragmentation with the threshold value. The threshold value represents an acceptable level of fragmentation in the data sets of the file system.

Fragmentation control for performing deduplication operations

A storage server is coupled to a storage device that stores blocks of data, and generates a fingerprint for each data block stored on the storage device. The storage server creates a fingerprints datastore that is divided into a primary datastore and a secondary datastore. The primary datastore comprises a single entry for each unique fingerprint and the secondary datastore comprises an entry having an identical fingerprint as an entry in the primary datastore. The storage server merges entries in a changelog with the entries in the primary datastore to identify duplicate data blocks in the storage device and frees the identified duplicate data blocks in the storage device. The storage server stores the entries that correspond to the freed data blocks to a third datastore and overwrites the primary datastore with the entries from the merged data that correspond to the unique fingerprints to create an updated primary datastore.

Fingerprints datastore and stale fingerprint removal in de-duplication environments

A method and apparatus for deduplication of files of a storage system is described. During a gathering phase, a file may be simultaneously processed by two or more threads to produce and store content identifiers for data blocks of the file. Each file may be sub-divided into multiple file sub-portions, each file sub-portion comprising a predetermined number of data blocks. A thread may be assigned to each sub-portion of a file for processing the data blocks. The currently assigned sub-portion for each thread may be recorded and used upon a system crash to restart each scanner thread at the currently assigned sub-portion to minimize the data blocks that are re-processed. The size of a file sub-portion may be predetermined based on the organization of inode data structures representing the files (e.g., based on the maximum number of pointers that an indirect block in the inode data structure may contain).

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Bengaluru, India

Alok Sharma