# US 10,120,577 B2 · Method and system for implementing performance tier de-duplication in a virtualization environment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,120,577 B2 - Document ID: US10120577B2 - Status: Granted - Kind: B2 - Application number: 15/154,835 - Filed: 2016-05-13 - Published: 2016-12-29 - Granted: 2018-11-06 - Earliest claimed: 2013-08-23 - Applicants: Nutanix, Inc. - Inventors: Kannan Muthukkaruppan; Karthik Ranganathan - Web page: https://patentgrep.com/patent/US10120577B2 ## CPC - G06F 3/0608: {Saving storage space on storage systems} - G06F 3/061: {Improving I/O performance} - G06F 3/0641: {De-duplication techniques} - G06F 3/0659: {Command handling arrangements, e.g. command buffers, queues, command scheduling} - G06F 3/0664: {at device level, e.g. emulation of a storage device or system} - G06F 3/067: {Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]} - G06F 3/0685: {Hybrid storage combining heterogeneous device types, e.g. hierarchical storage, hybrid arrays} - G06F 9/45558: {Hypervisor-specific management and integration aspects} - G06F 12/0813: with a network or matrix configuration - G06F 2009/45583: {Memory management, e.g. access or allocation} - G06F 2212/1016: Performance improvement - G06F 2212/1044: Space efficiency improvement - G06F 2212/151: Emulated environment, e.g. virtual machine - G06F 2212/154: Networked environment - G06F 2212/6042: Allocation of cache space to multiple users or processors - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract The present application provides an improved approach for managing performance tier de-duplication in a virtualization environment. A content cache is implemented on high performance tiers of storage in order to maintain a working set for the user virtual machines accessing the system, and associates fingerprints with data stored therein. During write requests from the user virtual machines, fingerprints are calculated for the data to be written. However, no de-duplication is performed during the write. During read requests, fingerprints corresponding to the data to be read are retrieved and matched with the fingerprints associated with the data in the content cache. Thus, while multiple pieces of data having the same fingerprints may be written to the lower performance tiers of storage, only one of those pieces of data having that fingerprint will be stored in the content cache for fulfilling read requests. ## Claims ### Claim 1 A computer-implemented method for de-duplication, comprising: receiving a read request from one or more virtual machines to read at least a portion of data; identifying fingerprints corresponding to the portion of data to be read; accessing a content cache that stores a set of data for the one or more virtual machines and fingerprints corresponding to the cached set of data, wherein the content cache is configured such that it does not store more than one copy of data corresponding to a particular fingerprint; determining if any of the identified fingerprints corresponding to the portion of data being requested match any of the fingerprints corresponding to the cached set of data; if a match is found, retrieving data corresponding to the matched fingerprints from the cached set of data; and if a match is not found, retrieving the portion of data from an extent store and writing a copy of the portion of data into the content cache, wherein the extent store is a persistent storage device associated with one or more virtual disks. ### Claim 2 (depends on 1) The computer-implemented method of claim 1, wherein the fingerprints comprise SHA1 fingerprints. ### Claim 3 (depends on 1) The computer-implemented method of claim 1, wherein the fingerprints are associated with locations on the one or more virtual disks. ### Claim 4 (depends on 1) The computer-implemented method of claim 1, wherein the content cache is implemented in RAM or flash. ### Claim 5 (depends on 1) The computer-implemented method of claim 1, wherein the content cache associates fingerprints with working set of data using a hash table. ### Claim 6 (depends on 1) The computer-implemented method of claim 1, wherein the content cache comprises one or more LRU chains. ### Claim 7 (depends on 6) The computer-implemented method of claim 6, wherein the LRU chains comprise a single-touch LRU chain and a multi-touch LRU chain. ### Claim 8 A system for de-duplication in a virtualization environment, comprising: a processor; a memory comprising computer code executed using the processor, in which the computer code implements: receiving a read request from one or more virtual machines to read at least a portion of data; identifying fingerprints corresponding to the portion of data to be read; accessing a content cache that stores a set of data for the one or more virtual machines and fingerprints corresponding to the cached set of data, wherein the content cache is configured such that it does not store more than one copy of data corresponding to a particular fingerprint; determining if any of the identified fingerprints corresponding to the portion of data being requested match any of the fingerprints corresponding to the cached set of data; if a match is found, retrieving data corresponding to the matched fingerprints from the cached set of data; and if a match is not found, retrieving the portion of data from an extent store and writing a copy of the portion of data into the content cache, wherein the extent store is a persistent storage device associated with one or more virtual disks. ### Claim 9 (depends on 8) The system of claim 8, wherein the fingerprints comprise SHA1 fingerprints. ### Claim 10 (depends on 8) The system of claim 8, wherein the fingerprints are associated with locations on the one or more virtual disks. ### Claim 11 (depends on 8) The system of claim 8, wherein the content cache is implemented in RAM or flash. ### Claim 12 (depends on 8) The system of claim 8, wherein the content cache associates fingerprints with working set of data using a hash table. ### Claim 13 (depends on 8) The system of claim 8, wherein the content cache comprises one or more LRU chains. ### Claim 14 (depends on 13) The system of claim 13, wherein the LRU chains comprise a single-touch LRU chain and a multi-touch LRU chain. ### Claim 15 A computer program product embodied on a non-transitory computer readable medium, the computer readable medium having stored thereon a sequence of instructions which, when executed by a processor causes the processor to execute a method for de-duplication in a virtualization environment, the method comprising: receiving a read request from one or more virtual machines to read at least a portion of data; identifying fingerprints corresponding to the portion of data to be read; accessing a content cache that stores a set of data for the one or more virtual machines and fingerprints corresponding to the cached set of data, wherein the content cache is configured such that it does not store more than one copy of data corresponding to a particular fingerprint; determining if any of the identified fingerprints corresponding to the portion of data being requested match any of the fingerprints corresponding to the cached set of data; if a match is found, retrieving data corresponding to the matched fingerprints from the cached set of data; and if a match is not found, retrieving the portion of data from an extent store and writing a copy of the portion of data into the content cache, wherein the extent store is a persistent storage device associated with one or more virtual disks. ### Claim 16 (depends on 15) The computer program product of claim 15, wherein the fingerprints comprise SHA1 fingerprints. ### Claim 17 (depends on 15) The computer program product of claim 15, wherein the fingerprints are associated with locations on the one or more virtual disks. ### Claim 18 (depends on 15) The computer program product of claim 15, wherein the content cache is implemented in RAM or flash. ### Claim 19 (depends on 15) The computer program product of claim 15, wherein the content cache associates fingerprints with working set of data using a hash table. ### Claim 20 (depends on 15) The computer program product of claim 15, wherein the content cache comprises one or more LRU chains. ### Claim 21 (depends on 20) The computer program product of claim 20, wherein the LRU chains comprise a single-touch LRU chain and a multi-touch LRU chain.